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Carnivoran Ecology
Carnivoran Ecology
The Evolution and Function of
Communities
Steven W. Buskirk
Professor Emeritus, University of Wyoming
Great Clarendon Street, Oxford, OX2 6DP,
United Kingdom
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Preface
This book arose from my several decades of interest a small part of our growing understanding of
in and research on carnivorans. Like many young what limits the distributions and abundances of
people with naturalist tendencies, I was particu- carnivorans.
larly intrigued by my early encounters with wild During those early years, I depended on the stan-
carnivorans—their rarity, elusiveness, and implicit dard academic references of the day: journal arti-
threat to my well-being. I vividly recall seeing my cles, monographs, book chapters, theses, disserta-
first bear track on a solo backpacking trip in the tions, and R. F. Ewer’s (1973) The carnivores. Ewer’s
Sierra Nevada of California, followed by a sleep- monograph was the definitive source for carnivo-
less night spent contemplating my fate. I recall the ran biology—especially paleontology and behavior.
horror of my older sister when I asked her to stop Writing the current account nearly fifty years on,
our parents’ car so that I could retrieve a road-killed I benefitted from a wealth of high-quality material
domestic cat and add its skull to my collection. In facilitated by the revolution in publishing—a prolif-
the summers of my college years, working as a tour eration of journal titles, many of them open access,
guide in Mount McKinley (now Denali) National expanded opportunities for scientists in develop-
Park, Alaska, I observed regular interactions involving countries to publish their work, and many more
ing wolves, caribou, brown bears, moose, red foxes, women working and publishing as scientists. The
and other species. Some of these observations were period since 2000 has offered unprecedented oppor-
dramatic and photogenic, but curious as well. Why tunities to write a book such as this, and the pan-
did 150-kg brown bears invest so much effort to demic of 2020–22 gave my isolation and focus new
capture 200-g ground squirrels? Why did wolves purpose.
give birth in the same dens for decades on end, What qualifies me to write a book about all car-
even though they were well known and prone nivorans? I am not the most prolific author of car-
to human disturbance? Why were coyotes deathly nivoran papers, nor the one with the broadest geo-
afraid of being anywhere near wolves, while red graphic experience. Others have spent more time
foxes merely stayed out of their grasp? in the field, or are more quantitative than I. How-
My PhD research and subsequent faculty ever, my interests extend in multiple directions,
appointment in Zoology and Physiology at the all of which relate to how carnivorans succeed or
University of Wyoming gave me opportunities fail in the wild. I am as intrigued by answers to
to pursue these kinds of questions. While most big ecological questions as by solutions to specific
carnivoran research of that time gravitated to conservation problems. I am as satisfied by under-
intraspecific and predator–prey interactions, standing of some ecological puzzle as by watching
my interests ranged more widely. My research a large carnivore stalk an ungulate. I appreciate new
addressed various mechanisms by which car- discoveries in natural history as much as I do stud-
nivorans might be limited: thermal energetics, ies of functional genomics. I also value those who
allometry, tooth morphology, fasting endurance, study carnivorans and share their findings with sci-
genetic variability, and interspecific competition. entists and the public. This group overlaps strongly
I learned that predator–prey interactions were with those committed to assuring the presence and
vi P R E FA C E
importance of carnivorans in future communities. References cited

This book is really about, for, and the result of
Ewer, R.F. (1973). The carnivores. Ithaca: Cornell University
the work of carnivoran biologists, conservationists, Press.
and naturalists, both professional and amateur. It
is about their passion. Last of all, hopefully it is a
motivation for others to follow in their tracks.
Steven W. Buskirk
Professor Emeritus, University of Wyoming
December 10, 2022
Silver City, New Mexico, US
Acknowledgments
Many people supported and aided me in writing Van Valkenburgh, Lars Werdelin, and Andrzej
this book. My wife Beth encouraged me at every Zalewski. Collectively, the reviewers corrected
stage and tolerated many interruptions to our rou- errors of fact, identified important omissions, pro-
tine so that I could spend time writing. Close col- vided more pertinent or more recent references,
leagues Dennis Knight and Carlos Martinez del Rio and improved the organization and presentation.
were reliable discussants and sources of encour- Without their help the project would not have been
agement early in the conception and early writing possible.
phases. Hannah Sease produced all graphic arts The illustrations strengthen the narrative
work, keeping pace with my requests throughout throughout, and some of the finest artwork and
her graduate studies in graphic arts. photography were contributed gratis or licensed
The William Robertson Coe Library at the Univer- at reduced rates. I particularly thank Justin Binfet,
sity of Wyoming provided outstanding support, fill- Darin Croft, Walton Ford, Stan Gehrt, Don Gutoski,
ing scores of requests for materials, and the J. Cloyd Esperanza Iranzo, Jeffrey Kerby, Janet Kessler,
Miller Library at Western New Mexico University Débora Kloster, Susan McConnell, Chris Mills,
provided additional assistance. My academic home, Larissa Nituch, Velizar Simeonovski, Alejandro
the Department of Zoology and Physiology at the Travaini, Juan Zanón, the Philmont Scout Ranch,
University of Wyoming, provided office space and and Kasmin Gallery. Although I have tried to
other support for most of duration of the project. select photos taken under natural conditions, I
I benefitted from reviews by over thirty scien- cannot assure that none was staged or in some way
tists, eight of them commissioned by Oxford Uni- contrived.
versity Press, and others solicited by me, who The staff of Oxford Press were most support-
generously reviewed chapters or shorter sections: ive and encouraging. Ian Sterling was immediately
Benjamin Allen, Rudy Boonstra, Jeff Bowman, receptive when I approached him with my pro-
Joseph Bump, Emiliano Donadio, Jacob Goheen, posal, and consistently improved my presentation
Henry Harlow, Dennis Knight, Serge Lariviere, as well as my understandings of how the book could
Paul Leberg, Jason Lillegraven, Carlos Martinez be made most useful. Charlie Bath provided excel-
del Rio, Sterling Miller, Robert Naiman, Richard lent suggestions on draft chapters, and Katie Lakina
Ostfeld, Jonathan Pauli, James D. Rose, Oswald shepherded the project through the editorial and
Schmitz, John Schoen, Qian-Quan Sun, Blaire production processes.
Contents
1 Introduction to Carnivoran Ecology 1

1.1 “Carnivoran” vs. “carnivorous” 1
1.2 The carnivorans—who and where? 5
1.3 The growth of knowledge 5
1.4 Purpose and organization of the book 7
1.5 Context in carnivoran ecology 8
1.6 Nomenclature 8
References 9
2 Functional morphology 11
2.1 The skull 11
2.1.1 Dentition 12
2.2 Post-cranial skeleton 15
2.2.1 Fossorial movement 16
2.2.2 Running and walking 16
2.2.3 Climbing 17
2.2.4 Swimming and deep diving 18
2.3 Other adaptations to aquatic living 19
2.4 Gut morphology 20
2.5 The integument 20
2.6 The major ecomorphotypes 22
2.6.1 Scansorial ecomorph 23
2.6.2 Dog-like ecomorph 23
2.6.3 Cat-like ecomorph 23
2.6.4 Scavenger ecomorph 24
2.6.5 Semi-fossorial ecomorph 24
2.6.6 Semi-aquatic ecomorph 24
2.6.7 Marine ecomorph 25
2.6.8 Intermediate and unique ecomorphs 25
Key points 25
References 26
3 Evolution and historical biogeography 29

3.1 Evidence for mammalian phylogeny 29
3.2 Early mammals 29
x CONTENTS
3.3 Early carnivorans 31

3.3.1 Continental biogeography 31
3.3.2 Early carnivoran radiations 36
3.4 Body size in macroevolution 43
Key points 44
References 45
4 Physiological ecology 49
4.1 Digestion 49
4.1.1 Soluble carbohydrates 50
4.1.2 Gut passage 51
4.2 Dietary requirements 52
4.2.1 Amino acids and fatty acids 52
4.2.2 Macronutrients 53
4.3 Metabolism and growth 53
4.3.1 Metabolism 53
4.3.2 Growth 55
4.4 Body temperature and torpor 55
4.4.1 Body temperature 55
4.4.2 Torpor 56
4.5 Energy storage and fasting 56
4.6 Osmoregulation and kidney function 58
4.7 Detoxification and self-medication 60
4.8 Reproduction 61
4.8.1 General patterns 61
4.8.2 Embryonic diapause 61
4.8.3 Induced ovulation 63
4.9 Scaling physiology to populations 64
Key points 65
References 65
5 Sensory biology and neuroanatomy 71

5.1 The senses 71
5.1.1 Tactile 71
5.1.2 Chemosense 71
5.1.3 Hearing 75
5.1.4 Electromagnetic radiation 75
5.1.5 Geomagnetic 78
5.2 Brain morphology 78
5.2.1 Brain size 79
5.2.2 Brain regional size 81
Key points 81
References 82
6 Community ecology 87
6.1 Nutrient cycling and transport 87
6.2 Direct effects on soil 90
CONTENTS xi
6.3 Disease ecology 92

6.3.1 Factors affecting disease prevalence in carnivorans 92
6.3.2 Predation and disease prevalence in prey 93
6.3.3 Trophic transmission and prey behaviors 94
6.4 Scavenging and access to carrion 95
6.5 Direct effects on plant life cycles 96
6.5.1 Pollination 96
6.5.2 Seed dispersal 97
6.5.3 Seed exploitation 98
Key points 99
References 99
7 Interactions with non-prey animals 103

7.1 Facilitation 103
7.2 Competition and coexistence 106
7.2.1 Exploitation competition 106
7.2.2 Interference competition 106
7.2.3 Influences on interference 109
7.2.4 Mesopredator release 110
7.2.5 Demographic effects of interference 111
7.2.6 Coexistence or interference? 111
7.2.7 Abiotic factors and interference 114
7.2.8 Human influence on interference 116
7.3 Domestic dogs as competitors with wild carnivorans 119
7.4 Carnivorans: apex, meso-, and other 120
Key points 121
References 121
8 Interactions with prey 127

8.1 Who eats whom? 127
8.2 Do carnivorans limit prey abundance? 128
8.2.1 Bottom-up vs. top-down effects on herbivores 130
8.3 Trophic diversity and limiting effects 132
8.4 How herbivores avoid predation 132
8.4.1 Antipredator structures 132
8.4.2 Antipredator chemicals 134
8.4.3 Induced predator defenses 135
8.5 Physiological and demographic responses to risk 138
8.6 Carnivorans and prey population cycles 140
8.7 “Prudent” and “wasteful” predators 142
8.8 Apparent competition 143
Key points 145
References 146
9 Cascades 153
9.1 Ecological cascades 153
xii CONTENTS
9.2 Trophic cascades 157

9.2.1 Density-mediated trophic cascades 157
9.2.2 Strength of density-mediated trophic cascades 162
9.2.3 Behaviorally mediated trophic cascades 162
9.2.4 Strength of behaviorally mediated trophic cascades 167
9.2.5 Evidence required for trophic cascades 168
Key points 169
References 169
10 Population ecology 173

10.1 How carnivorans die 173
10.2 Demography 174
10.3 Spatial aspects of population organization 175
10.3.1 Dispersal and homing 175
10.3.2 Migration 176
10.3.3 Population genetic structure 177
10.3.4 Hybridization and introgression 179
10.4 Carnivoran life histories 182
10.5 Social and mating systems 184
10.6 Adaptation in populations 186
Key points 187
References 188
11 How carnivorans affect humans 193

11.1 Negative effects 193
11.1.1 Attacks on humans 193
11.1.2 Attacks on domestic animals 194
11.1.3 Killing wild animals valued by humans 196
11.1.4 Limiting species of conservation concern 197
11.1.5 Interfering with tourism 197
11.2 Positive effects 198
11.2.1 Direct benefits to humans 198
11.2.2 Ecological services 203
11.3 Mixed effects 203
11.3.1 Roles in disease ecology 203
11.3.2 Roles in conserving other species 205
11.4 Spiritual and emotional values 208
Key points 208
References 212
12 How humans affect carnivorans 219

12.1 The state of the carnivoran fauna 219
12.2 Mechanisms of effects 220
12.3 Direct mortality: poisoning, hunting, and trapping 221
12.4 Other agents of direct mortality 226
12.5 Physical exclusion 226
CONTENTS xiii
12.6 Effects on behavior 227

12.7 Habitat- and prey-mediated effects 229
12.8 Disease-related effects 229
12.9 Recolonizations, reintroductions, and restorations 230
12.10 Reintroduction and restoration outcomes 232
12.11 Trophic subsidies 234
12.12 Other subsidies 235
12.13 Mediation of competitive interactions 236
12.14 Conservation genetics 236
12.15 Global climate change 239
Key points 242
References 243
Appendix I List of extant carnivoran species 251

References 256
Appendix II List of non-carnivoran species mentioned 257
Glossary 259
Index 263
CHAPTER 1
Introduction to Carnivoran Ecology
Order Carnivora represents one of the most species- emotions are stronger when we imagine ourselves
rich, phenotypically diverse, widely distributed, or animals we own as prey. As a result, we have long
and ecologically influential mammalian lineages. imbued carnivorans with spiritual powers to match
Its extant members live on all continents and in their impressive physical abilities, and our ances-
all oceans and range from vole-sized (c. 30 g) tors represented carnivorans in some of the earliest
to larger than a rhinoceros (c. 4,000 kg). They figurative art (Figure 1.3) (Hart and Sussman, 2008;
eat diverse foods including leaves, fruits, insects, Azéma, 2015). Today, we continue to use carnivo-
honey, marine invertebrates, and mammals larger rans to symbolize wildness, ferocity, and indepen-
than themselves. Some species live below ground dence in visual and literary arts. Every pocket and
for weeks at a time, a few live mostly in the fold of most human cultures—languages, parables,
forest canopy, and others live at sea for months spiritual beliefs, and symbols—is rich with carnivo-
on end. Many are wilderness dwellers, wary of ran references.
humans and their activities, while some non-
domestic species thrive in major cities, largely
1.1 “Carnivoran” vs. “carnivorous”
dependent on humans for food, shelter, or protec-
tion from larger, wilder carnivorans. No other mam- The terms “mammalian predator,” “mammalian
malian order approaches Carnivora in the breadth carnivore,” and “carnivoran” are not precisely syn-
of adaptive suites shown and ecological niches onymous. Predators are animals that kill and con-
occupied. sume multicellular animals (Taylor, 1984), whether
Humans have always been keenly interested in one at a time, or filtered from water by the thou-
carnivorans. Our hominin ancestors were preyed sands. Eagles, dragonflies, and blue whales are
on by carnivorans and competed with them for predators. By contrast, a carnivore consumes the
food. Both species hunted the same prey and drove flesh of animals, whether it kills or scavenges it; vul-
each other away from prey carcasses (Figure 1.1) tures, snakes, and Venus fly traps are carnivores and
(Espigares et al., 2013). Paleolithic humans con- carnivorous. Carnivorans, the subject of this book,
verted a potential competitor, the wolf, to a partner. are exclusively mammals in Order Carnivora—a
The resultant dog was the first domesticated animal, branch of the tree of life. Species in the order
and became essential to human lives, providing a may pursue and kill vertebrates, eat termites exca-
food source, vigilance against intruders, transport vated from soil, or subsist entirely on plant parts
of possessions, and assistance in hunting and herd- (Figure 1.4). “Hypercarnivore” sometimes indicates
ing (Figure 1.2). Dogs became so important to early a species with a diet exceeding some threshold level
humans that they are credited with shaping human of vertebrate prey, typically killed rather than scav-
evolution as much as humans shaped theirs (Pierotti enged. Most members of the cat family, the Felidae,
and Fogg, 2017). are considered hypercarnivores. Other terms, such
The life-or-death nature of predation elicits strong as “mesopredator,” “apex predator,” and “keystone
human emotions—either the predator eats and predator,” have imprecise meanings that I parse as
lives, or the prey escapes and survives. These they arise in the book.
Carnivoran Ecology. Steven W. Buskirk, Oxford University Press. © Steven W. Buskirk (2023). DOI: 10.1093/oso/9780192863249.003.0001
2 CARNIVORAN ECOLOGY
Figure 1.1 The first contact between humans and the saber-toothed Smilodon in America, interpreted by Velizar Simeonovski. Carnivorans have
been competitors with and potential predators of hominins from before we became humans through to today.
Painting: © Velizar Simeonovski.
I N T R O D U C T I O N TO C A R N I V O R A N E C O L O G Y 3
Figure 1.2 Lions (right) depicted on the walls of Salle du Fond in Chauvet-Pont d’Arc Cave, France, dating to 32,000–30,000 years ago. The lions
appear to be watching a rhinoceros on a distant panel. Carnivorans were subjects of some of the earliest figurative art. Vertical scratches in the
lower right and on the rhinoceros painting were made by cave bears trapped in deep chambers.
Photo: J. Clottes in Azéma (2015), CC 4.0.
As is often the case in biology, the defining traits defining the group, because all modern species have
of the Carnivora—the traits held by all members that trait, but some early carnivorans did not.
of the lineage, both living and extinct—are difficult Predatory placental mammals—those that pri-
to state without qualification. Traditionally, biolo- marily kill other animals for food—occur in several
gists have cited the presence of cheek teeth that have orders, including shrews and moles (Order Sorico-
shearing functions, comprising the upper fourth morpha), bats (Chiroptera), whales (Cetacea), pan-
premolar (P4 ) and lower first molar (M1 ). All living golins (Pholidota), and hairy anteaters (Pilosa). If
carnivorans have ancestors with this trait. However, we broaden our frame of reference to include mar-
living genets, bears, and seals have secondarily lost supial predators, several additional orders must
the shearing function of those teeth, and at least be included as mammalian carnivores. Even some
one species has lost those teeth completely. Some obligate herbivores, among them ungulates and
prehistoric linages of other carnivorous mammals rodents, prey on or scavenge vertebrates oppor-
had shearing cheek teeth, but they occupied other tunistically (Boonstra et al., 1990; Dudley et al., 2016).
positions in the tooth row, for example M1 and M2 . Finally, many extinct non-carnivoran lineages were
They were not homologous to modern carnassials, at least partially carnivorous. Clearly, Order Car-
and the lineages that exhibited them have no living nivora is not unique among mammals in killing and
descendants. The fused scaphoid and lunate carpal eating vertebrates. This book is about a mammalian
bones (the scapholunate) are sometimes regarded as lineage, not a foraging style or trophic niche.
Figure 1.3 Rock art in northwestern Saudi Arabia showing dogs resembling modern Canaan dogs assisting with lion hunting. Various glyphs
from this site include the earliest depictions of dogs on leashes, 12,000–10,000 years old. The upper image is shaded to show relief that is less
visible in the lower, unaltered image.
Photo: Guagnin et al. (2018, Figure 10) by permission.
Herbivorous Carnivorous
mammals Carnivora mammals
Figure 1.4 Venn diagram of the

relationships between carnivory, herbivory,
and Order Carnivora. Herbivorous mammals
overlap with the Carnivora, and the
Carnivora overlap with carnivorous
mammals. Elephants are herbivorous
non-carnivoran mammals. The giant panda
is an herbivorous carnivoran. The brown
bear is an omnivorous carnivoran, neither
fully herbivorous nor carnivorous. The tiger is
a carnivorous carnivoran, and the killer Elephant Killer whale
whale is a carnivorous non-carnivoran
mammal. In this book I use “carnivorous” to Giant panda Tiger
denote diet, and “carnivoran” to denote
phylogeny—inclusion in Order Carnivora. Brown bear
1.2 The carnivorans—who and where? nearly cosmopolitan, found on all continents except
Antarctica and Australia before humans trans-
The approximately 287 extant species of carnivo-
ported them. On the other hand, the eight species
rans are organized into fifteen currently recognized
of Eupleridae occur only on Madagascar Island,
families (Appendix I) and occur on all continents, if
their common ancestor having rafted there from
we include seals that haul out on Antarctic beaches.
the African mainland around 20 million years ago
These numbers change as we learn more about
(Ma). The thirty-three extant species of seals, sea
how mammal lineages are related. For example, the
lions, and walrus make up the pinniped (ear foot)
neotropical olinguito recently has been identified as
group—a lineage comprising two or three families
distinct from other olingos, and the African golden
that arose from a single aquatic ancestor. “Fissiped”
wolf was judged a separate species from the golden
(split foot), on the other hand, denotes the remain-
jackal, (Gaubert et al., 2012; Helgen et al., 2013). On
ing, mostly terrestrial, non-pinniped carnivorans.
the other hand, the long-recognized red wolf of east-
ern North America is now regarded as an ancient
hybrid of the wolf and the coyote, with uncertain 1.3 The growth of knowledge
endangered species status (vonHoldt et al., 2016, but
Before 1900, understanding of carnivoran ecology
see Hohenlohe et al., 2017). At the level of taxo-
(as opposed to natural history) was limited, often
nomic families, the skunks and stink badgers were
based on lore and conjecture. Much of our knowl-
grouped with weasels and otters in the Mustelidae
edge of their genetics, behavior, and reproduction
before Family Mephitidae was recognized as war-
at that time resulted from observing domestic cats,
ranting recognition (Dragoo and Honeycutt, 1999).
ferrets, and dogs, and farmed minks and foxes
With each such discovery, our knowledge of car-
(Figure 1.5). Very little scientific knowledge about
nivoran classification becomes more reflective of
wild carnivorans existed, and most interest cen-
evolutionary history, as revealed through genetic
tered on the value of their furs or other body
and morphological studies.
parts and the threat they posed to agriculture. They
Carnivoran species are distributed unevenly
were difficult to study directly because of their low
across lineages and continents. Family Mustel-
densities, elusive behaviors, and constant persecu-
idae holds sixty species, whereas the Nandiniidae,
tion near humans. Well into the twentieth century,
Ailuridae, and Odobenidae hold a single species
the leading ecological questions about carnivorans
each. The Felidae, Canidae, and Mustelidae are
dealt with how many ungulates, waterfowl, and reported on genetic traits of cheetahs related to
other valued vertebrates they killed and how to mit- evolutionary or ecological processes. Genetic deple-
igate those losses (Leopold, 1933). In the late twen- tion in other carnivoran species became a research
tieth century, however, perspectives shifted, tools focus as well.
improved, and ecological research on this group The American mink is an example of a car-
surged. The number of scientific journal articles nivoran that has stimulated research as a result
indexed by Web of Science with “Carnivora” as a of the great ecological harm it causes. Introduced
topic increased by a factor of eleven from 1992 to to Europe and South America during the twen-
2016, compared with a factor of four for “mam- tieth century for fur production, it today poses
mal” and six for “Mammalia.” New understandings threats on both continents, spurring intensive study
of carnivoran biology, especially ecology, began to (Bonesi and Palazon, 2007; Crego et al., 2016). Over
unfold in the 1960s, when carnivorans gained signif- the past twenty-five years, published studies on
icance in conservation issues, either as threatened the ecology of invasive American minks outside
taxa or as agents of endangerment of other taxa of North America have greatly outnumbered those
or communities. For example, the severe contrac- conducted within the species’ native range.
tion in distribution and abundance of the brown This expansion of knowledge reflects that
bear in the contiguous United States from 1850 humans need to know much more about car-
to 1950 resulted in greatly expanded research in nivoran ecology than they did seventy years ago.
bear biology, broadly cast. Of 159 scientific jour- For example, public health planners now must
nal articles with the topics “grizzly bear + Yellow- consider whether the most rapidly emerging
stone” indexed by Web of Science, all but two were infectious diseases of humans are influenced by
published subsequent to the initial 1975 listing of the diversity and abundance of wild carnivorans
the Yellowstone population under the Endangered (Section 11.3.1) (Levi et al., 2012, Hofmeester et al.,
Species Act. Similarly, no articles indexed by Web 2017). The current incidence and severity of such
of Science dealt with the population genetics of the debilitating zoonoses as avian and swine influenza,
cheetah before the discovery by O’Brien and col- Lyme disease, and tick-borne encephalitis may
leagues (1983) that cheetahs exhibited low genetic be mediated by the presence and abundance of
variability. This finding had such strong conser- predators—many of them carnivorans—that kill
vation implications that 153 subsequent articles intermediate or alternate hosts (Thulin et al., 2015).
Figure 1.5 Farmed black-phase red

foxes at Fromm Fox Farm, Wisconsin, US,
in the early twentieth century. Knowledge
of carnivoran reproductive and nutritional
physiology during that era came largely
from observing domesticated and farmed
animals.
Photo: Fromm Historical Society.
Even the viral pandemic COVID-19 has been linked Because of my focus on community ecology, the
to transmission of the SARS-CoV-2 virus among reader will find only passing mention of some top-
various wild and domestic mammals—particularly ics central to carnivoran biology in the past. These
carnivorans—and humans. The carnivorans include include intraspecific behavioral interactions: social-
domestic dogs and cats, captive tigers, and Amer- ity, mating systems, parental care, and territoriality.
ican minks (Vinodh Kumar et al., 2020; Hammer These topics were at the forefront of carnivoran ecol-
et al., 2021). ogy during the 1970s—the heyday of interest in kin
At the same time, carnivorans are credited selection—but they are peripheral to community
with performing valuable ecological services not interactions. Ecological systems are complex, with
understood decades ago. In Chapter 6 I show indistinct boundaries between components. Preda-
that bears are recognized for transporting marine- tion relates to competition, and competition affects
derived nutrients in salmon carcasses from spawn- population growth. Population density affects dis-
ing streams to neighboring forests along the North persal, which, in turn, drives colonization and bio-
Pacific Rim. Leopards and pumas protect some geography. This complexity makes ecology difficult
plants from overuse by herbivores. Fruit-eating car- to compartmentalize, and my chapter organiza-
nivorans transport seeds away from parent plants, tion requires the reader to navigate specific topics
in some cases more effectively than birds or her- via the index, in addition to the table of contents.
bivorous mammals. Leopards in India even receive For example, the reader interested in population
credit for reducing human fatalities inflicted by feral biology will find carnivoran-induced changes in
dogs, although leopards themselves kill a small prey populations covered in Chapter 8, but the
number of humans. Each of these functions and demography of carnivorans themselves is treated in
services has been recognized or better understood Chapter 10. Dental adaptations are mostly covered
recently, contributing to a much richer and more in Chapter 2, but some other aspects of digestive
nuanced picture of how carnivorans affect human morphology fit better in Chapter 4, the chapter on
lives and well-being. physiology. The responses of prey species to car-
nivorans can be behavioral, physiological, demo-
1.4 Purpose and organization graphic, or have uncertain mechanisms, and these
processes are covered in various sections, best
of the book
located via the index. Chemical defenses against
This book is intended as a text for a college course carnivorans by prey and other carnivorans, and by
in community ecology or predation ecology, and plants against herbivores, as well as detoxification
as a reference for students (academic or otherwise) of venoms by carnivorans, are each treated sepa-
of ecology who have some background in biolog- rately, in sections best located in the index. Habitat
ical concepts and vocabulary. It emphasizes docu- ecology is a traditional and highly diffuse topic that
mented, mechanistic explanations for the ecology of permeates wildlife biology. Scarcely a section of this
carnivorans and species they interact with. Impor- book does not have habitat aspects. However, no
tantly, I do not review all biological knowledge that aspect of carnivoran habitat ecology seems unique
applies to the Carnivora—only those aspects that to the order, so I fold discussions of habitat in with
set carnivorans apart; many aspects of carnivoran others.
biology resemble those of other mammalian orders. This account is based almost entirely on the peer-
For example, the vibrissae of carnivorans are well reviewed scientific literature. I use both primary
developed and important for tactile sensation, but and secondary sources, relying on community-level
the primary research model for this organ has been analyses, meta-analyses, or reviews where possible.
the laboratory rat, not a carnivoran. An analogous I have tried to be comparative throughout, contrast-
situation exists for gut fermentation—it is rare in the ing carnivoran families with each other and car-
Carnivora and is better understood from studies of nivorans with other vertebrate carnivores, includ-
other mammalian orders. To help with vocabulary ing marsupials, reptiles, and birds. I have tended
issues, I provide a glossary of technical terms. to prefer mechanistically based studies to those
based only on correlative results or modeling and have caused the group to radiate into an astonish-
have favored widely accessible publications to more ing range of phenotypes. Trophic niche determines
obscure ones. dentition, digestive process, and gut passage. Size of
While I have tried to enhance the geographic and prey species affects hunting behavior, frequency of
taxonomic diversity of the case studies that I cited, predation events, and competitive interactions with
I recognize that the literature is biased toward stud- scavengers. Context lies at the intellectual core of
ies from developed countries and on high-profile carnivoran ecology, and I have embraced it fully.
or endangered carnivorans. Therefore, my presen- Conservation also is an applied arena in which
tation no doubt includes cultural biases that affect context is all-important. Carnivorans are widely
the generality of my conclusions. In some cases regarded as one of the most threatened mammalian
where examples support a generalization and mul- lineages, with severe challenges to species, sub-
tiple published examples illustrate the point, I have species, and populations across Earth. On the other
tended to cite a study from a region or ecosys- hand, carnivorans also cause or exacerbate con-
tem that is less well represented in the literature, servation problems for other species that are rare
rather than an equally illustrative study from North or threatened. Further complicating the picture,
America or western Europe. humans have benefited some carnivoran species (or
Some unifying themes connect the various facets stopped persecuting them), and others are reoccu-
of carnivoran ecology, and I return to them fre- pying their former geographic ranges with or with-
quently. These factors explain much of the great out human assistance. Carnivore conservation does
diversity of form and function across the Carnivora, not merely represent a sad list of decline, dysfunc-
as well as many of the differences between car- tion, and disappearance, but examples—admittedly
nivorans and other mammalian orders. The most anomalous—of restoration and independent recov-
important are body size, metabolic rate, and trophic ery. Ecological and socio-economic context deter-
level. Allometry is the study of body size and its mine how carnivorans are faring in the modern
consequences, and the reader will note the recur- world. All told, the biology of the Carnivora is an
ring importance of allometry in many processes at extraordinarily rich subdiscipline, full of pattern,
physiological and community levels (Calder, 1984). nuance, contingency, and relevance to human cul-
Metabolic rate is a function of body size, body ture and livelihoods.
temperature, and mitochondrial density, and has
strong explanatory power in carnivoran ecology.
Trophic level is correlated with these factors; car-
1.6 Nomenclature
nivorans that eat large mammalian prey exemplify
the constraints imposed and benefits conferred by For the current scientific nomenclature of carnivo-
high metabolic rate and large bodies—high foraging rans, I have modified Wilson and Reeder (2005)
costs and maintenance costs—but food availability to reflect recent taxonomic revisions (Appendix I).
that is more seasonally consistent than for herbi- Common names are more problematic, because all
vores or predators of ectotherms. By watching for are local or regional, and using one requires select-
the recurring mention of body size, metabolic rate, ing from among those used by various indigenous
and trophic level, the reader can appreciate how groups or colonizing nations, or the native tongue
much carnivoran diversity arises from only a few of the original naming authority. Because I write in
principles. English, I default to my language, but I have tried
to use the common name applied most geographi-
cally broadly where the species occurs. For example,
Puma concolor occurs from Patagonia, South Amer-
1.5 Context in carnivoran ecology
ica to Yukon Territory, North America, with many
While I search for pattern in carnivoran ecology, locally used names over its range. However, the
I make scarcely a generalization about this group common name applied over most of the geographic
without a qualification or caveat. Contingencies range is “puma,” which I use here.
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CHAPTER 2
Functional morphology
Functional morphology considers how organ- and lateral motion of the mandible. The shearing func-
tissue-level structure and coloration are the basis tion of the carnassials occurs on one side at a time,
of function. At smaller physical scales, “histol- and the mandible shifts toward the shearing side
ogy,” “cell structure,” and “molecular biology” are for any single bite. More herbivorous carnivorans—
more common terms. Here I consider structure with the giant panda and spectacled bears—do not have
direct ecological relevance, important for locomo- shallower mandibular fossae as might be expected
tion, prey handling, crypsis, communication, and for the greater range of motion required for grind-
reproduction. “Ecomorphology” is a synonym, and ing leaves and stems. Instead, their fossae are even
living and fossil carnivorans are well represented deeper than those of more predaceous carnivorans
as subjects. The carnivoran-specific literature on and the mandible shifts laterally during a single bite
this subject focuses mostly on three morphological to achieve the grinding effect. This chewing motion
regions: the skull, the forelimbs, and the hindlimbs. differs from that found in all other herbivorous
The skull is significant because of the great range mammals.
of functions it performs and the spatial trade-offs The adaptive trajectory toward killing prey larger
between them. The forelimb is important because than the predator requires further modification to
its structure differs across locomotor and foraging the skull. This niche is occupied by large felids,
styles: swimming, digging through soil, sprinting, canids, some ursids, and some hyaenids. Canine
and climbing all leave strong adaptive signatures. teeth may seem remarkably uniform in shape across
To a lesser extent, the hindlimb also reflects adapta- extant carnivorans, but in fact show strong modifi-
tions to locomotor modes. cation for various roles. The single most biomechan-
ically challenging function of the skull and teeth is
applying jaw force to the tips of the canine teeth
2.1 The skull
while handling struggling large prey (Penrose et al.,
The skull is the bony structure with the most com- 2020). However, that task differs across carnivo-
plex design trade-offs and constraints of any ver- ran families. Slender, sharp canines are found in
tebrate body part. In carnivorans its components taxa (e.g. felids) that kill by quick stabs to the cer-
have key functions in display-defense, prey capture, vical region (dorsal spine or neck vessels). More
mastication, vision, hearing, balance, olfaction, cra- robust canines occur in predators that take longer
nial enervation, and endocrine function, as well as to kill prey that struggle, or that consume bony
housing the brain. The largest body of work dealing material. Canids tend to have more curved canine
with skull morphology—dentition aside—concerns teeth, plausibly to hold struggling prey for longer
how trophic specialization affects non-dental skull times (Pollock et al., 2021), and not only must the
features. Moore (2009, p. 197) explored how the canine teeth be stout, but also the jaw adductor
ancestral carnivoran jaw joint diverged in two tra- muscles and associated bony structures must be
jectories for dietary specializations. The jaw of most strengthened—otherwise, the braincase is vulner-
carnivorans features a deep mandibular fossa on able. These adductors, originating from the sagit-
the temporal (= “squamosal”) bone that limits the tal crest, the nuchal crest, and the zygomatic arch,
are especially powerful in predators of large prey. pair: P4 /M1 . This feature allows severing of muscle
The sagittal crest runs antero-posteriorly along the and connective tissue, so that parts of large car-
dorsal midline and is the site of origin for the tem- casses can be removed and either swallowed or con-
poralis muscle, the largest jaw adductor. It inserts sumed away from the prey carcass, thereby reduc-
on the coronoid process of the mandible and closes ing conflict. The earliest carnivorans had less promi-
the jaw. Tall and massive sagittal crests, resembling nent carnassial P4 /M1 structures than do modern
the sails of sailfish—are found in several carnivo- predaceous forms. All dental evolution involved
ran lineages: pinnipeds, hyaenids, ursids, and some changes in size and shape, as well as some tooth
mustelids. The masseter muscle, another powerful loss; no carnivoran lineage shows an increase in
jaw adductor, originates from the zygomatic arch tooth number. Incisors have undergone relatively
and inserts onto the lateral mandible. The nuchal little change in morphology or number, and the
crest, which follows the dorso-posterior margin of canines are retained even in species that do not use
the occipital bone, is the site of insertion of neck them to handle prey. This reflects the dual func-
extensor muscles that originate from the cervical tions of canines: prey handling and display-defense.
vertebrae, powering head movements used in sub- Aardwolves, bat-eared foxes, and pandas—none
duing large prey. Among carnivoran predators of of them primarily predators of vertebrates—have
large prey, all of these structures are large rela- canines similar in shape and only slightly smaller
tive to the floor of the braincase (Penrose et al., to those of vertebrate-killing relatives. In at least
2016). five predaceous mammalian lineages (two metathe-
The bony labyrinth is a complex structure that rian, three carnivoran), canine teeth became so elon-
reflects feeding and non-feeding forces. Encased gated that they extended outside the oral cavity.
in the temporal bone, it comprises organs of bal- Most of these taxa showed the saber-toothed con-
ance (the semicircular canals with ampullae) and dition, using canines for prey killing, whereas the
hearing (the cochlea). While not feeding structures oversized canines of walruses function primarily in
per se, the canals are key to maintaining equilib- display and defense.
rium and spatial orientation by measuring angu- Consistent with adaptive changes to the carnas-
lar acceleration in three planes. It is therefore an sials themselves, other tooth positions reflect the
important sense for mammals, especially carnivo- importance of killing large prey vs. other trophic
rans, with active locomotor and foraging styles. strategies (Figure 2.1). With specialization on preda-
That is, they must stabilize the head in order to tion and a meat diet came the reduction in size and
allow the brain to process visual inputs while pur- number of the post-carnassial teeth (M1−3 , M2−3 ). In
suing and subduing prey. Schwab and colleagues felids, the best extant examples, premolars P1−2 and
(2019) showed that all dimensions of the semicir- P1−2 are lost as well, because a diet of animal soft tis-
cular canals were larger in ambushing carnivorans sue requires little mastication before swallowing—
than in omnivores or pounce hunters. A strong duodenal lipases and peptidases are sufficient
phylogenetic signal was apparent as well. Other to initiate digestion. The second trajectory—a
skull features are closely tied to sensory modalities trend toward omnivory, frugivory, and folivory—
(Section 5.1.2). retained the post-carnassials and modified them
for grinding, giving them multi-cusped, rounded
(bunodont) shapes. Bunodont teeth crush inverte-
2.1.1 Dentition
brate exoskeletons and shells (e.g. in the walrus
Much study of modern and prehistoric diets of and otter), and coarsely grind plant material (e.g.
carnivorans and other carnivorous mammals has in bears). In the highly carnivorous spotted hyena,
concerned prey handling (gripping and killing) the pre-carnassial premolars are enlarged for bone
and masticating. Basal carnivorans had the primi- crushing—important for a scavenger of large ungu-
tive eutherian dental formula—I3 /I3 , C1 /C1 , P4 /P4 , late carcasses. Piscivorous pinnipeds tend to retain
M3 /M3 —and teeth in some of these positions large, sharp canines, but have lost the position-
evolved more quickly than in others. A landmark specific functions of ancestral cheek teeth, includ-
in carnivoran dentition is the carnassial (shearing) ing the carnassial pair (Box 2.1). Instead, they tend
FUNCTIONAL MORPHOLOGY 13
(a)
M1
(b)
(c)
M1
Figure 2.1 Lower dentitions of the earliest and modern carnivorans, showing enlargement, reduction, and loss of cheek teeth with diverging
diets. A: Protictis (Viverravidae), an insectivore-carnivore of the Paleocene (M3 lost). B: Modern lion, a strict carnivore (M2–3 lost). C: Red fox, an
omnivore (M2 retained, bunodont, M3 vestigial). D: Giant panda, an obligate folivore (M2–3 bunodont). E: Aardwolf, an obligate termitivore (M2–3
variably vestigial or lost). F: California sea lion, an obligate piscivore (M2–3 lost, post-canines reduced and homodont).
(d)
M1
(e)
(f)
M1
Figure 2.1 continued
toward generalized, nearly homodont cheek teeth 2016). Importantly, carnivoran dental specializa-
(Figure 2.1F), consistent with swallowing fish whole tions have tended to be irreversible over evolu-
or severing them into large pieces (Kienle and Berta, tionary time; they disappear via lineage extinction,
Box 2.1 Filter-feeding carnivorans
Several pinnipeds have evolved highly specialized cheek in the crabeater seal of the Antarctic Ocean, which eats
teeth that facilitate the filtering of aquatic invertebrates. The almost entirely finger-sized krill. The Baikal seal of Russia
water is gulped into the oral cavity and pharynx, then ejected shows a more moderate expression of the same trait—it
past the projections on the cheek teeth (Figure 2.2). The trait feeds heavily on freshwater amphipods (Watanabe et al.,
has arisen several times in the phocids and in both freshwa- 2020).
ter and marine forms. It reaches its most extreme expression
Figure 2.2 The cheek teeth of the filter-feeding crabeater seal, showing dental projections that filter krill from sea water.
Photo: © Te Papa Tongarewa Museum of New Zealand.
rather than by restoring lost tooth functions. This 2.2 Post-cranial skeleton
is similar to mammalian dental evolution gener-
No other mammalian order matches the range of
ally, but contrasts with that of squamate reptiles,
morphological adaptations for locomotion and for-
in which multiple tooth cusps arose to grind veg-
aging observed in the Carnivora. Several locomo-
etation. In some lineages, these cusps disappeared,
tor modalities are recognizable, and some species
and cheek teeth reverted to unicuspid form as diets
exhibit more than one. Basal carnivorans were
returned to carnivory (Lafuma et al., 2021).
locomotor generalists, walking, running, and climb- (gaits faster than a walk): coursing and sprint-
ing, but specializations arose early in several lin- ing. All carnivorans that run fast tend toward
eages. elongated metapodials and proximal phalanges,
which increase stride length. The long bones of
their limbs are as long as predicted from body
2.2.1 Fossorial movement mass (Figure 2.3) (Harris and Steudel, 1997), with
prey captured in the jaws or forelimbs. The clav-
The Mustelidae and Mephitidae include several
icle is lost, allowing scapular rotation along the
obligatory below-ground foragers, that is, they must
dorso-ventrally elongated ribcage, and the digiti-
move soil to forage. These include American bad-
grade stance further lengthens the stride. Coursers
gers, European badgers, honey badgers, hog bad-
such as the canids, wolverine, and spotted hyena
gers, ferret badgers, ferrets, polecats, and stink
trot, gallop, or bound long distances at sustained
badgers. Mustelids smaller than ferrets also for-
intermediate speeds, whereas sprinters, typically
age underground, but do not move soil. Fossorial
ambush predators, run fast in short bursts, typ-
forms have forelimbs modified for digging, includ-
ically while pursuing prey. Some coursers have
ing longer claws and elongated olecranon processes
limited hip and elbow rotation, which increases run-
of the ulna, which strengthened the digging stroke
ning efficiency at the expense of maneuvering and
(Rose et al. 2014). They also exhibit enlarged scapu-
manipulating prey. Distinct suites of adaptations
lar surfaces and shortened limbs to allow moving
are associated with coursing vs. ambushing. Cours-
in constricted spaces (Figure 2.3) (Van Valkenburgh,
ing species cover their home ranges at a walk or trot,
1987). The distal limbs tend toward the planti-
detecting prey via sight, hearing, or scent. Once a
grade condition, in which the podial-metapodial
prey animal is encountered, the courser may seize
joint touches the ground, as seen in the hind foot
and kill it with a bite (e.g. small canids), disable
of a bear. As well, the plane of the forefoot bends
it by exhaustion and blood loss, injure its cervi-
medially (supinates) in the American badger to
cal spine, or asphyxiate it by crushing the trachea.
allow excavated soil to pass beneath the abdomen
Their running muscles have high concentrations of
and between the hind legs. The clavicle is vestigial
myoglobin-rich, slow-oxidative fibers, with dense
or completely lost, allowing greater range of fore-
mitochondria, which are fatigue-resistant at sus-
limb motion. Domestic ferrets walk in tunnels by
tained intermediate speeds (see Goldspink, 1977
lowering and flattening the lumbar spine, which
for canid–felid comparison, Hill et al., 2012). These
serves to decrease the effective lengths of the limbs.
muscles tend to have high densities of capillaries
These adaptations allow ferrets to walk at the same
essential for sustained oxygen delivery (Sjøgaard,
speed along subterranean burrows as above ground
1982). Coursers cannot easily grasp prey with the
(Horner and Biknevicius, 2010). A slender snout in
forelimbs, having little elbow rotation and claws
some species facilitates seizing prey in tight spaces,
that cannot protract.
and the pinnae are reduced. In addition to burrow-
Sprinters, by contrast, traverse their home ranges
dwellers, several small and mid-sized mustelids
at a walk, lie in wait for longer periods, tend to
forage or occupy dens in talus fields, hollow tree
detect prey by vision rather than olfaction, and
boles or other confined spaces (Harris and Steudel,
capture them after brief pursuits, in other words,
1997). Many small canids, herpestids, and viver-
ambushing. Most felids are such predators, and are
rids occupy burrows for protection from enemies or
physiologically similar to coursers, but run faster for
weather, but not necessarily for foraging.
briefer periods and tire more quickly. Their running
muscles are mostly fast glycolytic and have higher
rates of contraction, less myoglobin, and fewer
2.2.2 Running and walking
mitochondria than do coursers. They metabolize
Most terrestrial carnivorans trot, bound, or run. anaerobically during peak exertion, accumulating
I distinguish between two patterns of cursation lactic acid in muscle cells. Cats and other ambush
1000
Maned wolf
Canada lynx
Geoffroy’s cat
European badger
Hind limb length (mm)
No. Amer. martens

Stink badger
100
European polecat
Canidae
Least weasel Felidae
Hyaenidae
Mustelidae
Viverridae +
Herpestidae
10
0.05 0.5 5 50
Body mass (kg)
Figure 2.3 Hind limb length in relation to body mass for sixty-three terrestrial carnivoran species. Mustelids that excavate soil have proportionally
short legs. Canada lynx and boreal forest martens, which walk on snow in winter, have long legs.
Modified from Harris and Steudel (1997).
carnivorans rotate the radius well, consistent with 2.2.3 Climbing

forelimb grasping, and the claws—sharper than
Most carnivoran families include species that range
for coursers or diggers—are protractible. Elbow
from scansorial—semi-arboreal—to highly arbo-
rotation and sharp claws also facilitate tree climbing
real. These species also climb cliffs and buildings,
(Figure 2.4) (Stein et al., 2015). Cheetahs are inter-
and most are small-bodied (Van Valkenburgh, 1987).
mediate between coursers and ambushers in these
The most arboreal include procyonids (e.g. kinka-
traits; they have highly flexible spines that increase
jou and olingos), a few viverrids and feliforms (e.g.
stride length. The scapholunate bone, the largest
palm civets and linsangs), and euplerids of Mada-
carpel bone in the carnivoran wrist, represents the
gascar. Tree climbing is carried out in various ways,
fused scaphoid and lunate (separate bones in pre-
involving differing adaptive suites. Two species
decessors to the Miacoidea (Rose, 2006, p. 129)).
(kinkajou and binturong) benefit from partially pre-
This fusion was earlier regarded as adaptive specif-
hensile tails that feature some muscular control of
ically for running, which is intuitive inasmuch as
the distal caudal vertebrae (Figure 2.5). Protractible
reduction in the size and number of distal limb
claws allow grasping of the tree bole, and rota-
elements is a common cursorial adaptation. Analy-
tion of the hip allows some species to descend
ses of shape across carnivoran foraging types show
the bole head-first. Small (and juvenile) bears are
that the scapholunate has been modified for pure
scansorial, having recurved claws on the forelimbs
cursation vs. grappling with prey in the respective
and a sesamoid carpal bone encased in tendons
hunting types (Dunn et al., 2019).
attached to the radius (Ewer, 1998; Fisher, 2011).
Figure 2.4 A caracal rotates an elbow to lick the plantar surface of a forefoot. Elbow rotation is important for grasping prey and for climbing
trees. The claws of the forelimb are normally retracted.
Photo: © four oaks/Canstock.
The latter trait is well developed in both species 2.2.4 Swimming and deep diving
of panda of and the kinkajou and is so well devel-
Mammals returned to the marine environment
oped in the giant panda as to suggest adaptation
seven times over their evolution, and of the five
for grasping bamboo during feeding or climbing
surviving marine lineages, three (pinnipeds, polar
(Gould, 1978). Climbing bears also have robust sub-
bear, and sea otter) are carnivoran (Uhen, 2007).
scapularis muscles, which insert along the posterior
Among pinniped families, we see the strongest
margin of the scapula and stabilize the shoulder
adaptations to swimming and deep diving in the
when bears pull themselves up by their forelimbs
Phocidae. Their hind limbs have lost all locomo-
(Davis, 1949). Among canids, only the scansorial
tor function on land but are effective propulsive
gray foxes have somewhat sharp and recurved fore-
organs in water. By contrast, the Otariidae and
limb claws, climbing mostly by hopping from limb
Odobenidae support their posterior bodies on hind
to limb, rather than by hoisting themselves. Smaller
limbs to walk awkwardly on land, and dive effec-
felids ascend trees by either branch-hopping or by
tively to shallower depths than do phocids. The
grasping the bole. In addition to various musteloids
less derived semi-aquatic forms include (in approx-
and procyonids, several Oligocene felids were
imately decreasing order of aquatic adaptation) the
in this group; the latter likely used trees for
sea otter, other otters, minks, the otter civet, the
escape, rather than for foraging (Van Valkenburgh,
aquatic genet, raccoons, and the fishing cat. Fishing
1987).
cats, jaguars, and raccoons forage by wading and
predation, injuries from short falls, and crushing

by conspecifics on haul-outs or rookeries (Udevitz
et al., 2013).
2.3 Other adaptations to aquatic living

All adapted carnivoran swimmers display some
degree of streamlining, insulation, webbed or fin-
like distal limbs, reduced pinnae, and cardiopul-
monary adaptations to prolonged apnea. Enlarged
propulsive structures (webbing of digits, modifica-
tion of limbs to fin shapes) are blended with coor-
dinated trunk motion, so that the entire axial skele-
ton and associated muscles contribute to swimming
motion (Williams, 1999).
Among air-breathing vertebrates, carnivorans
live at a uniquely wide range of ambient pres-
sures. They occur at elevations above sea level as
high as 6000 meters in the case of the snow leop-
ard and 5100 meters for the Andean cat (Alianza
Gato Andino, unpublished data). The partial pres-
sure of oxygen at 6000 meters is around half its
value at sea level. By contrast, the southern ele-
phant seal dives to 2400 meters below the ocean
surface, where ambient pressures create gas pres-
sures in respiratory passages many times higher
than at sea level. The snow leopard lacks any known
Figure 2.5 The binturong (shown), a viverrid, and the kinkajou, a
procyonid, are among the most arboreal of carnivorans and have biochemical adaptations to high-altitude hypoxia
prehensile tails, like some arboreal primates. (Janecka et al. 2015); however, diving as deep as
Photo: © Pakhnyushchyy/iStock. elephant seals do requires extreme morphological
and biochemical adaptations. They include rib artic-
ulations that allow thoracic collapse, frontal sinuses
feeling for prey with their forelimbs, and swim on being reduced or lost, and lung alveoli that com-
the surface with limbs better suited for walking. press elastically to reduce gas exchange between
Jaguars can subsist on an almost exclusively aquatic blood and pulmonary passages at depth (Ponganis,
diet, while being equally well adapted to living in 2015; Curtis et al., 2015). Ambient pressure increases
arid habitats with scarce free water; their aquatic linearly by one atmosphere per ten meters of water
adaptations are entirely behavioral (Eriksson et al., depth, so that a diving mammal at 2400 meters is
2022). At the other carnivoran extreme, elephant exposed to around 240 atmospheres of pressure. The
seals spend 8–10 months/year at sea, dive to depths structures of a non-adapted mammal’s pulmonary
of over 1500 meters for durations of over 100 min- tract, from the pharynx to the alveoli, cannot with-
utes, and come ashore only to give birth, mate, stand the pressures of such dives without trauma.
and molt (DeLong and Stewart, 1991). The highly In deep-diving pinnipeds these structures collapse
marine habits of large seals create major life his- and rebound without injury.
tory trade-offs. Their large bodies and fat reserves Duration of dives is generally correlated with
reduce mass-specific thermal losses in cold water depth of dives because of transit times to depth,
and prolong fasting endurance. While on land, how- but the adaptations to deep vs. long-duration dives
ever, they are nearly immobile, and vulnerable to are distinct. Extended apnea is facilitated by high
blood volume, high hematocrit, high O2 binding intestines—more like pinnipeds than terrestrial
of hemoglobin, and concentrated myoglobin in mustelids—that are long for their body sizes. The
somatic muscles. Most oxygen is stored in muscle adaptive value of small intestines of such length
and blood, rather than in air in respiratory pas- has long puzzled physiologists (Maxwell, 1967).
sages. Further, the spleen stores oxygenated red The current hypothesis suggests this result is due
cells, which are released into the general circulation to the redirection of blood away from the gut under
under hypoxia. In addition, long-duration divers anoxic diving conditions. This suspends digestive
experience bradycardia, increase their anaerobic processes for extended periods and lengthened
metabolism, and temporarily reduce blood flow to small intestines compensate for lost time when
organs not essential during dives. Blood supply to divers return to the surface and circulation to the
and aerobic metabolism in the head, adrenal glands, gut is restored (Duque-Correa et al., 2021).
and placenta are maintained (Bininda-Emonds et al.,
2001; Ponganis, 2015).
2.5 The integument
The adaptive value of fur color and markings has
2.4 Gut morphology
been considered for various species and multiple
In comparison with other mammals, and setting hypotheses exist, of which crypsis and aposema-
aside deep divers, the carnivoran digestive tract is tism are the most common. Various carnivorans, like
remarkable for its simple form. It has no volume- other mammals, feature pelage that matches their
enhancing chambers, sacculation, or structures to background—dark in forest environments (Gloger’s
house fermenting microbes (Figure 2.6). This is so rule), light tan on arid, sandy backgrounds, and
even for species that evolved obligate herbivory white in snowy habitats (Caro and Mallarino, 2020).
millions of years ago; phylogeny shows a stronger Some pinniped species whelp white neonates where
signal than diet in carnivoran gut morphology. Sev- they are born on snowy backgrounds, but dark ones
eral factors complicate comparisons, however. Most in caves or on predator-free islands. Four carnivo-
variation in gut length lies in the small intestine; rans, three of them Mustela spp., undergo seasonal
colon length varies little with diet. Mustelids have color changes to white in winter. Two of those
total intestinal (small + large) lengths about 1.4 species do so only in the parts of their ranges with
times that for terrestrial carnivorans generally, for winter-long snow cover. Crypsis is also suggested
unclear reasons. The carnivoran caecum is rudimen- as the adaptive purpose for bold black and white
tary (e.g. in Canidae and Felidae) or absent (e.g. patches of the giant panda (Nokelainen et al. 2021).
in Ursidae, Mustelidae, and Procyonidae), unlike Aposematic coloration has received special consid-
that of hindgut-digesting herbivores (e.g. rabbits, eration in Carnivora because defensive weapons are
horses, and elephants). Carnivorans that eat more so widespread (Section 7.7.5; Newman et al., 2005;
plant leaves and stems tend toward longer caecae, Howell et al., 2021).
but no substantial microbial fermentation has been Many mammals reduce thermal losses via adap-
reported. The curiously long caecum of the domes- tive fur traits, and fur affects buoyancy in aquatic
tic dog—but not of wild canids—is consistent with species. Among small and mid-sized semiaquatic
the increase in grains in the human diet during carnivorans, the fur is dense, but subcutaneous fat
the agricultural revolution, which coincided with is slight or intermediate. Dense fur traps air that is
dog domestication (McGrosky et al., 2016). This sug- insulative and retains its volume during the shal-
gests potential post-gastric fermentation, but how low dives made by minks, civets, and otters. The sea
the products could be absorbed downstream of the otter, the smallest marine carnivoran, has the dens-
caecum is not known. est underfur reported for any mammal (Figure 2.7),
Marine carnivorans represent a special case of with over 1100 hairs/mm2 (Fish et al., 2002). Sea
digestive morphology, having intestinal lengths otter fur is the most buoyant of any fur reported,
1.4–2.8 times that predicted from body size which is important for reducing the contact area
(Williams et al., 2001). Sea otters have small between the integument and water while resting on
10 cm
10 cm
10 cm
Figure 2.6 Digestive tract length varies highly across mammals, changing partly with diet. The Canada lynx has a shorter digestive tract than a
ruminant herbivore of comparable body size (e.g. dik-dik). Pinnipeds (e.g. California sea lion) have especially long digestive tracts, even accounting
for body size. Scale bar is for digestive tracts.
Modified from Stevens and Hume (1995) and McGrosky et al. (2016).
1200
1000
Hair density (hairs/mm²)
800
600 Figure 2.7 Hair density of mammalian

species varies with aquatic living and with
400 body size. Air trapped between hairs
contributes both thermal insulation and
200 buoyancy. The largest-bodied pinnipeds
have low hair densities, whereas
0 small-bodied otters have high ones. This
partly reflects the dependence of
Fur
Wa
Pola
Pho
Sea
Bob
Red
Erm
Bro
Nor
Com
Eur
Nor
Sea
Am
buoyancy on water depth; deep divers
ope
lrus
wn
eric
th A
th A
sea
cids
ine
cat
otte
r be
lion
fox
mo
lose insulative effect of fur under high
ls
an m
an o
rat
s
mer
mer
ar
nm
r
ambient pressures. Values for pinnipeds
tter
ican
ican
usk
ink
are means of species means (phocids, n =
13; sea lions, n = 5; fur seals, n = 6). Data
r at
bea
otte
are from Liwanag et al. (2012, Table S4) and
ver
r
Fish et al. (2002, Figure 4).
the surface. This is especially so for females sup- to polar bears, and was considered a possible model
porting neonates on their torsos (Figure 2.8). Fur is for winter clothing design. However, Koon (1998)
a less-effective insulator for deep divers, because of pointed out that the scattering of light in the hair
gas compression at depth—the thickness of an insu- shaft was so great that little light travelled down a
lating air layer at 500 m depth is 2% what it is at single hair shaft to the skin. More recently, Khattab
the surface. The deepest pinniped divers have short, and Tributsch (2015) explained that the mechanism
stiff hairs, rather than air-trapping fur. In addition, observed in polar bears involves light transmis-
the largest marine carnivorans—elephant seals, sea sion via guard hair shafts collectively, not individu-
lions, and walruses—minimize mass-specific ther- ally, so that there is some radiation that makes its
mal losses via their large body sizes. Blubber is a way to the skin. However, the warming effect on
fair thermal insulator and has the added benefit an endotherm as large and well insulated as the
of energy storage and retaining its insulation and polar bear is modest. The fiber optic model has lost
buoyancy at depth (Liwanag et al., 2012). Subcu- explanatory power for how polar bears keep warm,
taneous fat is especially important for deep-diving and no longer inspires designers of cold-weather
pinnipeds, which spend a lot of diving time drifting apparel.
passively through the water column. Body condi-
tion (and therefore the blubber depot) affects drift
rates strongly. As elephant seals increase blubber 2.6 The major ecomorphotypes
depots, they become more buoyant but more hydro- Functional morphologists have tended to clump
dynamically resistant. The relationship is so strong fossil and living mammals into groups of dis-
that body condition can be estimated from drift crete types (“ecomorphs,” vs. “ecotypes”), an
rates, as recorded from pressure transducers (Biuw approach proposed by White and Keller (1984) and
et al., 2003). adapted to the Carnivora by Martin (1989). These
In the 1980s polar bears were proposed to rep- types are based mostly on locomotor and den-
resent a special mechanism of solar warming via tal traits and reflect major adaptive spaces. Exam-
translucent guard hairs that transmit visible and ples include species requiring burrowing vs. tree-
ultraviolet light down the length of the hair shaft, climbing, exhibiting dietary generalization vs. spe-
where it is absorbed by the darkly pigmented skin cialization, or ambushing vs. other means of prey
(Grojean et al. 1980). This “optical fiber” model of capture. Some of these suites of traits have appeared
solar heating held sway, was thought to be unique only once in the fossil record, whereas others have
Figure 2.8 Buoyancy is a critical feature

of the fur of sea otters, allowing them to
float on the surface with minimal contact
with cold water. Here a female supports a
neonate on its torso, above water level.
Resting adults and neonates metabolize
at elevated rates via mitochondrial proton
leak (Section 4.3.1).
Photo: © Jeanninebryan/CanStock.
arisen repeatedly. The strong marine adaptations of in peak running speeds, in climbing ability, in
the pinnipeds, specifically those for deep diving and maneuverability around obstacles, and in ability to
exposure to the open sea, arose only once in the Car- rotate the elbow (Anderrson and Werdelin, 2003).
nivora (Arnason et al., 2006). By contrast, the “saber- Early representatives included creodonts and some
toothed” condition of enlarged upper canines and amphicyonids (bear-dogs) of the Miocene (Viranta,
associated skull modifications appeared in multi- 1996). The most obvious extant representatives are
ple feliform lineages, none of which persisted to the canids and hyaenids, although the latter have inter-
present. mediate tails and limited cursorial abilities. The rise
of this type coincided with the appearance, at tem-
perate latitudes, of savannah beyond the margins
2.6.1 Scansorial ecomorph of moist riparian zones in the mid-Miocene. This
This small- to mid-sized ecomorphotype, the pre- major shift in temperate habitats initially produced,
dominant one in the earliest carnivorans, is associ- in temperate North America, woodland steppe,
ated with forested habitats, traveling on the ground followed by grass-dominated prairie by the early
or on tree branches, and eating small vertebrates, Pliocene. Steppe-like habitats provided the adaptive
insects, and soft mast. The body plan includes space for abundant large grazing herbivores, which
a somewhat elongated skull rostrum, long tail, promoted this carnivoran ecomorphotype (Webb,
elbows with intermediate rotation for climbing 1977; Janis et al., 2002).
and clamoring, and in highly frugivorous forms,
crushing cheek teeth. Modern representatives occur
among the Viverridae, Mustelidae, Procyonidae, 2.6.3 Cat-like ecomorph
and Nandiniidae (see Ercoli and Youlatos, 2016 for These animals occur in two discrete habitat types
discussion of the tayra). with associated adaptations. Forest-dwelling cats
have tended toward small bodies and forelimbs
with short, stout bones for climbing. By con-
2.6.2 Dog-like ecomorph
trast, open-country cats tend toward larger bodies,
Dog-like carnivorans have ranged in size from small longer, thinner bones and greater use of crouch-
to over 75 kg. They have had limbs of interme- ing and ambush (Schellhorn and Sanmugaraja,
diate length and long tails, and were coursers— 2015). Cat-like carnivorans have short rostra with
sustaining trotting for long durations, but limited strong binocular vision, variable tails, and recurved,
protractible claws. The elbow joint rotates well high speed. Its most distinctive features were cranial
for grasping prey and tree boles (Anderrson and and dental: powerful jaw musculature and large,
Werdelin, 2003). One extant exception is the chee- pyramidal premolars for cracking bones. Among
tah, which has reduced forelimb rotation and semi- extinct species, we see examples in the Borophag-
retractile claws, and uses longer chases to capture inae (Canidae), some creodonts, and some early
prey than do pure ambushers. Cat-like animals Laurasiatherian forms (Arctocyonia) that may have
have tended to be the largest-bodied carnivorans had ungulate or carnivoran ancestors. Australo-
in many fossil assemblages; small-bodied extant hyaena, a South American marsupial sparassodont,
species remain common (Van Valkenburgh, 2007). converged on the same ecomorph (Forasiepi et al.,
Prey can be larger or smaller than the predator, 2015). Among extant species, it is exemplified in
killed by either a bite to the dorsal cervical spine three species of hyaenids, the wolverine, and the
or (in the case of saber-toothed forms) laceration of ursids.
the neck vessels. The saber-tooted dentition evolved
twice outside of the Carnivora—in Machaeroides
2.6.5 Semi-fossorial ecomorph
(Creodonta) and Thylacosmilus (Sparassodonta)—
and multiple times within the Feliformia. Two These mostly small and mid-sized species either
major saber-toothed subtypes are recognized. The excavate burrows to forage or enlarge those made
scimitar-toothed feliforms had upper canines inter- by other species. I do not include the many species
mediate in length and elongated dorso-ventrally, of several families that use and modify under-
while flattened laterally. These teeth featured dis- ground dens or burrows to thermoregulate, avoid
tinct crenulations along their edges. Their legs were threats, or give birth. Among extinct forms, this
long and optic regions of the brain enlarged, adap- type was exemplified in several genera of Miocene
tive for bursts of speed and visually localizing prey. mustelids not ancestral to the modern analogues
By contrast, “dirk-toothed” animals had especially (Hochstein, 2007). In extant forms, it is more preva-
long upper canines, in Smilodon serrated along both lent among the Caniformia than in the Feliformia
margins. Their body plans featured shorter legs and and shows specific adaptations for either digging
enlarged olfactory bulbs in the brain in comparison or entering tight spaces: slender bodies, short legs,
with scimitar-toothed forms. Analyses of bone den- or elongated claws. Frontal sinuses tend to be lost
sity and stress modeling of the rostra of both sub- to conserve skull volume (Curtis et al., 2015). Asso-
types and modern lions have revealed differences in ciated with these characteristics are altricial young,
prey-killing styles (Figueirido et al., 2018). The dirk- geographic ranges that extend to high latitudes, and
toothed Smilodon seems to have used its shorter, invertebrate diets. Species that excavate their own
more powerful forelimbs to grasp prey while stab- burrows tend toward group denning, as opposed
bing the vascularized neck with its dirk-like canines. to group hunting (Noonan et al., 2015). Modern
Modern lions, with their much shorter and more examples include aardwolves, badgers, meerkats,
conical canines, are better suited to sustained multi- polecats, some Mustela spp., and some mephitids.
direction stresses experienced when they grasp and
hold struggling prey. Scimitar-toothed forms were
2.6.6 Semi-aquatic ecomorph
intermediate between Smilodon and modern lions
in their adaptations for stabbing vs. withstanding These are the otters of subfamily Lutrinae, which
lateral shaking. Some fossil feliforms combined ele- exhibit many standard aquatic adaptations: short-
ments of the two subtypes, featuring scimitar-like ened limbs and pinnae, elongated bodies, streamlin-
teeth, but stout, short limbs (Martin et al., 2000). ing, webbed digits, and dentition adapted for seiz-
ing and severing parts of fish, as well as crushing
the exoskeletons of invertebrates. Most swim pow-
2.6.4 Scavenger ecomorph
erfully and nimbly to depths of scores of meters,
This ecomorph was characterized by a robust skele- but return to land to rest, and all but the sea
ton adapted to trotting and running, but not at otter give birth in sheltered dens. European and
American minks are less derived for aquatic living, represents a unique carnivoran phenotype: a bur-
eating slower-moving fish, some small mammals, rowing termite eater with locomotor adaptations
and intertidal or shallow-water invertebrates. similar to canids but derived from a lineage that
radiated into ungulate predators and bone-cracking
scavengers.
2.6.7 Marine ecomorph
The seals, sea lions, and walruses exhibit extreme
marine adaptations among the Carnivora: large, Key points
streamlined bodies, limbs modified as flippers for
• Functional morphology examines relationships
swimming at the expense of walking, and den-
between structure and various kinds of perfor-
tal modifications for seizing fish before swallow-
mance at the organ or tissue scale. The most active
ing them whole, or for crushing invertebrates.
areas of carnivoran research have concerned the
Adaptations to deep and long-duration diving are
skull, fore- and hind limbs, and gastrointestinal
extensive: skeletal morphology, streamlining, oxy-
tract.
gen storage systems, circulatory redistribution, and
• Dental adaptations to hunting and vertebrate car-
endocrine adaptations to deep or long-duration
nivory include refinement of the shearing func-
dives. The sea otter combines elements of the semi-
tion of P4 -M1 , hyper-elongation of the canines in
aquatic and marine ecomorphs, diving only to shal-
some extinct lineages, and reduction or loss of
low depths, but being more aquatic-adapted than
premolars and post-carnassials. The incisors have
other otters in other respects.
changed little through carnivoran evolutionary
history.
• Omnivory, folivory, and a diet of mollusks tend
2.6.8 Intermediate and unique ecomorphs
to select for rounded cheek teeth and loss of the
Some extant species do not fit neatly into only shearing function and retention of premolars.
one of these named categories, and we can assume • Locomotor derivations from the early carnivoran
that some extinct ones did not either. Among liv- condition include suites of adaptations for dig-
ing forms, the boreal forest martens (five species ging and fossorial foraging, coursing, ambushing,
of Martes) forage near the ground or on the snow climbing, swimming, and diving to great depths.
surface, investigating burrows (or subnivean access • The guts of carnivorans are short and simple,
points) by scent. However, they also can forage, and tend toward evolutionary conservatism, with
rest, and den in the forest canopy, and rely season- only slight adaptation to folivory in extant foliv-
ally on foods of aquatic or marine origin. Mustelids orous forms. Pinnipeds have long guts for their
are typically regarded as short-legged, but martens body sizes.
are among the longest-legged carnivorans for their • Cardiopulmonary and circulatory adaptations in
body size (Figure 2.3). Long limbs permit them deep-diving pinnipeds are dramatic and relate
to traverse home ranges that are large for their to two discrete issues: hypoxia resulting from
body sizes, even by carnivoran standards (Buskirk extended duration dives, and pressure-related
and McDonald, 1989), but flexible spines allow effects of dives to great depths.
them to traverse narrow passages and negotiate • Ecomorphotypes (ecomorphs) are groups of
tree branches. Raccoons (Procyonidae) alternate species that tend toward similar morphologies
between shallow-water and riparian environments and niches, based mostly on locomotor morphol-
for foraging omnivorously, but climb trees for soft ogy and dentition. For carnivorans, these types
mast, predator escape, and denning. Giant pandas comprise tree-climbing forms, dog-like coursers,
(Ursidae) and red pandas (Ailuridae) convergently ambushers of several types, scavengers, semi-
evolved specialized morphologies for bamboo her- fossorial forms, marine dwellers, and intermedi-
bivory and tree climbing. Finally, the aardwolf ates.
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nivora,” in Gittleman, J.L. (ed.) Carnivore behavior, ecol- Histochemistry, 76, pp. 547–55.
ogy and evolution. Ithaca: Cornell University Press, Stein, A.B., Bourquin, S.L. and McNutt, J.W. (2015) “Avoid-
pp. 536–68. ing intraguild competition: leopard feeding ecology and
Martin, L.D. et al. (2000) “Three ways to be a saber-toothed prey caching in northern Botswana,” African Journal of
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Maxwell, G. (1967) Seals of the world. Boston: Houghton Stevens, C.E., and Hume, I.D. (1995). Comparative physi-
Mifflin. ology of the vertebrate digestive system. Second edition.
McGrosky, A. et al. (2016) “Gross intestinal morphology Cambridge: Cambridge University Press.
and allometry in Carnivora,” European Journal of Wildlife Udevitz. M.S. et al. (2013) “Potential population-level
Research, 62, pp. 395–405. effects of increased haulout-related mortality of Pacific
Moore, W.J. (2009). The mammalian skull. Cambridge: Cam- walrus calves,” Polar Biology, 36, pp. 291–8.
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Newman, C., Buesching, C.D. and Wolff, J.O. (2005) “The the sea after 300 million years,” Anatomical Record, 290,
function of facial masks in ‘midguild’ carnivores”, pp. 514–22.
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of fossoriality in the Carnivora: implications for feeding morphologies in the Carnivora,” Integrative and
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CHAPTER 3
Evolution and historical biogeography
The major processes of evolution above the species extinct forms to infer phylogeny to estimate diver-
level—macroevolution—are basic to understanding gence times. Regions of the genome that change
the structure and function of modern carnivoran rapidly, including those that do not code proteins
ecology. Some modern carnivorans occupy similar and are under weak (or no) selective pressure,
ecological niches to those of the earliest members of change rapidly enough that populations—or even
the order. Others are highly derived, having mor- individuals—of the same species can be discerned.
phological traits or ecological functions that arose— Other regions, which code for the basic architec-
in some cases multiple times across lineages—over ture of form and function, evolve slowly. If a focal
the course of carnivoran evolution. Competition branch of the tree of life has modern descendants
structured past carnivoran communities as it does that provide undegraded DNA, divergence times of
modern ones, although the inferential processes branches can be estimated. The combination of fos-
used by ecologists vs. paleoecologists differ. Here, sil and molecular evidence is a powerful tool for
I consider phylogenetic differentiation at the levels telling the evolutionary history of the Carnivora,
of subclass and family and the importance of geog- but the two lines of evidence can paint contradictory
raphy in producing the diversity and distributions pictures (Gura, 2000). Published phylogenies based
of carnivorans we see in fossil and modern forms. on molecular evidence are now calibrated to fossil-
based divergence dates, so that dated trees reflect
both kinds of evidence (e.g. Dornburg et al., 2012;
3.1 Evidence for mammalian phylogeny
Nyakatura and Bininda-Emonds, 2012). This is the
A major consideration in the reconstruction of car- current gold standard for vertebrate phylogenies.
nivoran evolutionary history is the inferential utility
of fossil vs. genetic evidence. Fossils provide evi-
3.2 Early mammals
dence of morphology, geographic location, and geo-
logical context. The morphology of preserved body The first mammals, as partially defined by a jaw
parts—particularly teeth, skulls, and long bones— joint in which the dentary bone of the lower jaw
provides information on how the animal lived, articulates with the squamosal (temporal) bone of
particularly its diet and style of locomotion. The the cranium, have been identified from the Late
geological contexts of fossil deposits provide esti- Triassic Period, around 205 Ma (Figure 3.1). They
mates of minimum ages of various lineages and descended from and strongly resembled an amniote
their relatedness. However, fossil representation lineage that began to display mammalian traits—
of past vertebrate diversity declines with increas- heterodont dentition, two occipital condyles, and
ing age, and phylogenetic relatedness can be con- distal limbs oriented antero-posteriorly—over the
fused with trait convergence. As a result, divergence previous 100 million years. These traits arose mul-
times and inferred relatedness of early carnivoran tiple times in the nearest non-mammalian lin-
lineages are less reliable than for those that are eage, Cynodontia, only one branch of which gave
more recent. Genetic methods, particularly since rise to mammals. The earliest mammals persisted
1990, have used DNA from living and recently until eutherian mammals, recognized in fossils by
Epoch Epoch
Age 66 Present HOLOCENE
(Ma) 2.6 PLEISTOCENE
PLIOCENE
5.3
Last Creodonta
CRETACEOUS MIOCENE
Eupleridae founding event
23
Pinniped divergence
145 OLIGOCENE
33.9
JURASSIC
EOCENE
201
55.8
TRIASSIC
PALEOCENE Caniformia-Feliformia
divergence
252 66
Mesozoic Cenozoic
Figure 3.1 Geologic time scales for the Mesozoic and Cenozoic eras, with key events in carnivoran evolution.
Ma = million years before present. The boundary between Mesozoic and Cenozoic eras, formerly denoted the K–T (Cretaceous–Tertiary) boundary, is now called the
K–Pg (Cretaceous-Paleogene) boundary.
their forelimb bones and, except in the earliest Land mammals held ecologically minor roles com-
forms, absence of epipubic bones, diverged from pared to land reptiles, the latter being larger-bodied,
the metatherian lineage that led to marsupials about more diverse, and more abundant. The predaceous
160 Ma (Luo et al., 2011). The earliest eutherian for dinosaurs likely caused mammals to remain small,
which we have well-preserved skull and postcra- nocturnal, and rare.
nial bones had five upper and four lower incisors These ecological circumstances changed abruptly
on each side, single upper and lower canines, and at the Cretaceous–Paleogene (K–Pg, formerly K–T)
five premolars and three molars in each jaw (I5 /I4 , boundary, about 66.5 Ma, when an extraterrestrial
C1 /C1 , P5 /P5 , M3 /M3 ). Its three-cusped cheek teeth bolide struck the coastline of modern Yucatan, Mex-
were consistent with a diet dominated by insects; ico. The resulting pulse of heat, lasting mere hours,
it had the limb joints of a scansorial tree-climber killed nearly all forms of terrestrial vertebrate life
and was mouse-sized. Eutherians remained rare that could not shelter in water, in underground
and small-bodied for the remainder of the Meso- burrows, or in caves, over most of the planet
zoic Era. Most were omnivores no larger than rats, (Robertson et al., 2004). How many mammalian lin-
although descriptions exist of badger-sized preda- eages survived the event is unclear, but molecular
tors that ate small dinosaurs (Hu et al., 2005). tools have identified four major continental centers
Another random document with
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Hysterical contracture, like hysterical paralysis, may assume a
variety of forms: it may be hemiplegic, monoplegic, paraplegic,
alternating, or local, as of the ocular muscles, the facial or neck
muscles; laryngeal, pharyngeal, or œsophageal; of the fingers or of
the toes.
Richardson81 records the case of a young lady who saw in India a

religious devotee with his leg flexed upon his body and fastened
there. In a few hours she was found with her leg in a similar position,
and this contracture remained until after she had been taken to
London; then it disappeared as suddenly as it came. Conscious
purpose could not have maintained the leg in such a position for an
hour.
81 Diseases of Modern Life.
Some of the most remarkable cases of hysterical contracture are

those chiefly studied by the French, which originate before or after
convulsive seizures. Among the hystero-epileptics at Salpêtrière,
Richer82 reports many varieties of contracture: one with
hemianæsthesia and varying pain in the right side had permanent
contracture with tremulousness of the lower extremities; another,
with hemianæsthesia, pain, and frequent attacks of demoniacal
delirium and paresis, had momentary contractures of the upper and
lower extremities on the right side. In two other cases the
contractures were of the hemiplegic form, while three others were
paraplegic. In still other cases the contracture was monoplegic.
Besides hemiplegic, monoplegic, and paraplegic contractures, I have
seen illustrations of a number of local forms—among others, several
remarkable cases of hysterical contractures of the wrist and hand
and of the feet and toes, and one of hysterical torticollis. Hysterical
contracture in any of its forms may occur as an isolated symptom or
series of symptoms unconnected with the grave hysterical attack.
82 Op. cit.
Many forms of hysterical local spasms occur. Hysterical strabismus

from spasm of the ocular muscles has been observed. Several
cases have come under observation in which hysterical
blepharospasm was present. In these cases, when the lids are
forced open, the eyes disappeared in an extraordinary manner,
usually being drawn downward and toward the internal canthus.
Hysterical facial spasm occurs, and is usually clonic. One of the
most remarkable hysterical local spasmodic affections which has
come under personal observation was reported by me in a paper on
chorea.83 In this case the right ear twitched and moved up and down.
The movement of the ear was peculiar; it continued nearly all the
time, even when the patient's attention was not directed toward the
part. The act seemed to be partially under the control of the will, as
by a strong effort the left ear could be moved very slowly in the same
up-and-down direction. The nostrils and upper lip were affected with
twitching, and slight choreic movements were present in the entire
right side of the body. The patient's general condition improved
under treatment, but when last seen the local affection persisted,
although it was not so severe.
83 Philada. Med. Times, March 27, 1875.
Spasm of the pharynx, larynx, and œsophagus have been separated

by several authors. In hysterical laughter spasmodic contraction of
the laryngeal muscles occurs. Spasm of the glottis occurs in rare
cases, according to Rosenthal, from the reflex effect of
hyperæsthesia of the laryngeal mucous membrane, from irritation of
the recurrent laryngeal nerve. Death from asphyxia has occurred in
consequence of this form of spasm of the glottis.
Hysterical dysphagia, which is usually spasmodic, is sometimes a

dangerous, and always an annoying, affection. An unmarried lady,
forty years old, with a neurotic family history, a maternal uncle and
aunt having been insane, at intervals since puberty had had various
hysterical manifestations. After a severe winter, during which she
had suffered more or less with rheumatism, she became depressed
with reference to her spiritual condition: she had, in fact, a form of
mild religious melancholia. After this had lasted for weeks she began
to experience difficulty in swallowing. She would rise from the table
suddenly, alarmed and gasping, and exclaiming that she could not
swallow and was choking. She got so bad that she could not take
anything but liquid food, and not nearly enough of this. She believed
that her throat was gradually closing, and of course suspected
cancer. She was assured that if any local obstruction existed it could
be removed with one application of a probang. Cancer was also
confidently excluded, and she was given iron, valerian, and quinine,
and in a few days an instrument was passed down her throat. She
as told that she would have no more difficulty. Tonics and full feeding
were continued, and in less than a week she swallowed without any
difficulty.
Of the so-called hysterical asthma or hysterical breathing I have

seen several examples. A curious form of hysterical breathing, at
least partly spasmodic, recently came to the Philadelphia Polyclinic
—a young man twenty-one years of age, who confessed that he had
been guilty of excessive masturbation for five or six years. He had
been a moderate drinker and was the victim of an old hip disease.
According to his story, this abuse had never appeared to have
impaired his health until about one month before applying for
treatment, when he began to have attacks of peculiar breathing. He
would have a series of rapid, forced expirations which lasted for a
period of from one to two or three minutes. He would then stop for a
moment; then again the shallow breathing with forced expirations
would ensue. He said that he breathed in this way because he
thought he was going to die, and did so to keep alive. When he
stopped he felt cold. He thought his belly did not go outward as it
should in the act of breathing. During the time that the symptoms
had been present he had had several frightful attacks of excitement,
in one of which he ran breathing in the manner described to a drug-
store from one to two blocks away, jumping, gesticulating, and
calling for remedies. He had an anxious expression of the face, a
look of excitement and worriment. His pulse was 110 and weak.
Respirations during these attacks ranged from 38 to 50.
Coates,84 speaking of hysterical or nervous breathing, gives the

details of five cases. Four of these had been supposed to be
suffering from phthisis; the fifth was apparently a case of hypertrophy
of the heart. The breathing was quick and shallow. The patients
could not be induced to draw long breaths until the expedient was
adopted of having them count twenty without taking breath. During
this the lungs expanded perfectly, air entering freely into every part.
Coughing, and even blood-spitting of a venous character, were
present. They might perhaps be classed as cases of hysterical or
simulated phthisis.
84 British Medical Journal, 1884, ii. 13.
Vaginismus, or spasm of the vagina, may with propriety be regarded

as hysterical in some but not in all cases. Spasmodic contracture of
the sphincters of the bladder and anus is also mentioned by
Rosenthal. Goose-flesh, according to the same author, is a frequent
phenomenon in the hysterical, and is due to spasmodic contraction
of the muscular fibres contained within the skin.
The sensorial affections of hysteria can be classified according either

to character or location. According to the character of the sensory
disturbance a good practical arrangement is into cases of (1)
Anæsthesia; (2) paræsthesia; (3) hyperæsthesia; (4) neuralgias and
localized pains,—although one of these classes may sometimes be
difficult to separate from another, or a doubt may arise as to whether
or not a special symptom should be placed under one or another
head. In hysterical anæsthesia sensation is decreased or abolished;
in paræsthesia it is faulty or perverted; in hyperæsthesia it is
increased over a more or less extensive surface; in neuralgia, pain is
confined to certain nerve-trunks. The localized pains are neuralgic or
mimetic, and are found in special localities, as in joints and in the
breast.
Anæsthesia is one of the most frequent of hysterical phenomena, but

is not, as stated by some authorities, present in all cases of genuine
hysteria.
In 400 hysterical cases Briquet found 240 positive examples of

anæsthesia. In this statement, however, he does not include cases
of insensibility of the conjunctiva of the left eye or those cases in
which anæsthesia lasted but a few hours after an attack. It is safe to
say that anæsthesia of some sort is present in from 60 to 75 per
cent. of all cases of well-marked hysteria. Analgesia, or insensibility
to pain, is present frequently when loss or diminution of sensibility to
touch, pressure, heat and cold, etc., is not observed.
Hysterical anæsthesia, may be of various forms, according to the

parts of the body affected, as general anæsthesia; hemianæsthesia;
anæsthesia of the lower half of the body; anæsthesia of one limb or
one side of the face; anæsthesia of mucous membranes;
anæsthesia of muscles, bones, and joints; anæsthesia of the
viscera.
General anæsthesia is extremely rare. No example of it has ever

fallen under my observation, but by Briquet and others a few cases
have been reported.
Hemianæsthesia has in recent years received much attention from

neurologists. In hystero-epilepsy it is the rule to find it present, but it
is also observed in cases without spasms. In hemianæsthesia the
loss of sensation exists in one lateral half of the body. Parts are
insensible to various methods of stimulation—to impressions of
touch, pain, temperature, and weight. Sometimes the mucous
membranes of the side affected are involved. The sight, hearing,
taste, and smell are commonly impaired if not lost.
Much attention has been paid to the study of hemianæsthesia by

French physicians. Charcot85 has an admirable historical summary
and clinical description of the condition, leaving little for others to
add. Piorry, Macario, Gendrin, Szokalsky, and Briquet are referred to
by him. Briquet found it present in 93 cases out of 400. It is of much
more frequent occurrence on the left side. According to Briquet, 70
cases were affected on the left side to 20 on the right.
85 Op. cit.
Next to hemianæsthesia, anæsthesia of the lower half of the body is
most common in hysterical cases. While hemianæsthesia often
presents itself conjoined with hystero-epileptic symptoms,
anæsthesia of the lower half of the body may be present as
frequently without as with convulsive manifestations. Anæsthesia of
one limb or of one side of the face is almost as rare as general
anæsthesia, but does occur.
Anæsthesia of mucous membrane is an old observation. It may

affect mucous membranes everywhere—of the nose, pharynx,
larynx, vagina, urethra, the bladder, rectum, etc. Many of the peculiar
and apparently inexplicable hysterical symptoms are due to the
presence of this anæsthesia—such symptoms, for instance, as want
of inclination to evacuate the bowels or the bladder, absence of
sexual desire, absence of sensibility when applications are made to
the throat, etc. Loss of sensibility in muscles, bones, joints, and
viscera may be present, but is of course frequently overlooked from
want of minute investigation. In hemianæsthesia the viscera of the
anæsthetic side are sometimes hyperæsthetic. Thus the ovary, as
has been especially shown by Charcot, may be very painful on
pressure when the abdominal wall is perfectly insensible.
A striking characteristic of hysteroid sensory disorders of the

anæsthetic variety is the suddenness with which they come and go.
A complete transference of anæsthesia from one side of the body to
another may occur in a few seconds, either without special
interference or under the use of metals or electricity.
The term achromatopsia is due to Galezowski. Hysterical

achromatopsia is a condition in which there is a failure to appreciate
colors. In Daltonism, or true color-blindness, one color may be taken
for another; in achromatopsia the notion of color may be completely
lost. These colors are found by the patient to disappear in a regular
order, and return in a reverse order as the patient recovers. Some
remarkable cases of this kind have been reported as occurring
among French hysterics. A few examples of the same affection have
been reported in America. Sometimes the patient has lost perception
of one or several colors. When only one color is lost, it is usually the
violet; if two, the violet and green; then in regular succession follow
the colors of the spectrum.
Hysterical blindness and achromatopsia have been well studied by

Charcot and Richer and others of the French school. Special articles
on hysterical or simulated affections of the eye have also been
published by Schweigger,86 Harlan,87 and others.
86 “On Simulated Amaurosis,” by C. Schweigger, Prof. at the University of Berlin, New
York Medical Journal, Feb., 1866.
87 “Simulated Amaurosis,” by George C. Harlan, M.D., American Journal of Medical

Sciences, October, 1873; “Hysterical Affections of the Eye,” Transactions of the
College of Physicians of Philadelphia, 3d Series, vol. ii., 1876.
In several cases of hystero-epilepsy under my care both amblyopia

and achromatopsia were present. In one of these cases the patient
was unable to read print of any size or to distinguish any colors,
although she could tell that objects were being moved before the
eyes. An ophthalmoscopic examination showed a normal fundus.
Each eye was tested for near vision. It was found that she could read
quite well with the right eye, and not at all with the left. While reading
at about sixteen inches a convex glass of three inches focus was
placed in front of the right eye, but she still continued to read fluently.
C. H. Thomas of Philadelphia has given me the particulars of a case

of a woman about thirty-eight years old, both of whose eyes were, to
all appearances, absolutely blind. The attack came on suddenly, the
apparent cause seeming to be worry over a sick child.
Ophthalmoscopic and other examinations of the eye showed
nothing. She had no perception of light. She could look without
winking at a blinding reflection of a whitewashed fence. In six weeks
under a mere tentative treatment she got absolutely well. S. D.
Risley of Philadelphia,88 in a discussion at the Philadelphia
Neurological Society, held that the feeble innervation of the
hysterical patient was liable to diminish the range of accommodation
and power of convergence, rendering the comfortable use of the eye
impossible; and also that the feeble or deranged circulation in the
hysterical individual might set up a group of symptoms in the eye
presenting many of the characteristics of serious disease; which,
however, were not simulated, but were, in fact, a relative glaucoma.
While there was no absolute increase of intraocular tension, the
normal tension of the eyeball was sufficient to interrupt the entrance
of the feeble blood-stream into the eyes, and thus was set up the
same group of symptoms as were present in actual increase of
tension—viz. inadequate blood-supply to the retina, contracted field
of vision, impaired central perception, diminished range of
accommodation, and inability to use the eyes, particularly at a near
point.
88 The Polyclinic, vol. ii., No. 8, Feb. 15, 1885, p. 124.
Very few observations in cases of hysteria have been made with the
ophthalmoscope, and probably little is to be learned in this way. In
one of Charcot's patients, however, Galezowski saw an infiltration
and capillary reddening of the disc with fusiform dilatations of the
artery.
What might be termed hysterical dilatation of the pupil is sometimes

observed. In the case reported by Harlan, to be hereafter detailed,
the patient, a young girl who had a train of hysterical symptoms,
began to complain of blindness or imperfect vision in the right eye,
the pupil of which was found to be dilated. No proof could be
obtained of the use of any mydriatic. The pupil remained dilated
when exposed to a bright light. The dilatation came and went at
intervals, and finally disappeared under the applications of a wooden
magnet. W. Chester Roy has acquainted me with the facts of the
case of a man who could at will alternately contract and dilate his
pupils. This case would seem to lend color to the idea that the
hysterical girl may have had voluntary control of the pupillary
movements. In her case, however, only one pupil was involved. F. X.
Dercum has given me the particulars of a case of rhythmical
dilatation of the irides in a case of confirmed masturbation with
hysterical symptoms.
Hysterical deafness has been observed and studied. Walton,89 at
Charcot's suggestion, has published the results of the examination at
La Salpêtrière of 13 patients affected with hemianæsthesia with
reference to anæsthesia of hearing. He divides hemianæsthetic
patients into three classes: (1) Those with complete anæsthesia of
one side, the other side remaining normal; (2) those having
incomplete anæsthesia on one side, the other remaining normal; (3)
those with anæsthesia more or less complete on both sides. In the
first class anæsthesia of hearing extended to the deep parts of the
ear; the membrane of the drum could be touched without eliciting
any acknowledgment of sensation and without the least reflex
movement. He also showed that the anæsthesia extended to the
middle ear by the fact that insufflation by Politzer's air-douche
produced no sensation in the ear of the affected side. In this class
neither the watch, voice, nor tuning-fork was heard. In the second
class, with incomplete anæsthesia on one side, the lost sensibility
corresponded, as a rule, with that of the body in general. A common
form was analgesia with thermoanæsthesia and diminution of the
tactile sensibility. In the third class completeness of the anæsthesia
is rarely the same on both sides, a common form being complete
hemianæsthesia on one side and analgesia on the other.
89 Brain, January, 1883.
A noticeable feature in all the cases under consideration was the

uniformity with which the deafness for conveyance by the bone
exceeded that for sounds conveyed by the ear. Walton says: “This is
probably due to the fact that the vibrations conveyed to the ear by
the air are better adapted for the irritation of the peripheral auditory
apparatus than those conveyed by the bone. When, then, the
receptive power of the auditory centres is lessened, as is probably
the case in hysterical patients, the hearing for sounds conveyed by
the bones disappears before that for sounds conveyed by the ear.
This enfeeblement of the auditive centres in hysteria is quite
analogous to that in old age, in which, as is well known, the
perception for sounds conveyed by the bone disappears before that
for sounds conveyed by the air, the former being sometimes
completely lost before the age of sixty.” His principal conclusions are
as follows: (1) The sensibility of the deep parts of the ear, including
the tympanum and middle ear, disappears in hysterical
hemianæsthesia with that of other parts of the body, and in the same
degree. (2) The degree of deafness corresponds with that of the
general anæsthesia, being complete when the latter is complete, and
incomplete when the latter is incomplete. (3) When loss of hearing is
incomplete, the deafness for sounds conveyed by the bone exceeds
that for sounds conveyed by air. (4) When the transfer is made, the
hearing, as well as the general sensibility of the deep parts of the
ear, improves on one side (allowance being made for accidental
lesions in the ear itself) in exactly the same degree in which it
disappears on the other.
The following case has been kindly furnished to me by Charles S.

Turnbull, the patient having in the first instance come to Philadelphia
to consult his father, Laurence Turnbull: The patient was a young
lady from New Jersey, eighteen years old. Her general health was
good, although at times she had a pale and anxious look. She had
never had any unusual sickness. Soon after the death of her mother,
for whom she grieved very much, she began to grow deaf, and was
for a time treated by her family physician. When she first came to
Philadelphia she was absolutely deaf, but the most careful
examination failed to discover a cause for the deafness in any
affection of the external or middle ear. A current from ten cells of a
galvanic battery was painful, but elicited no sound. She declared that
she could not hear a musical box held close to the side of her head.
In communicating with her, everything had to be written. A faradic
current was used daily to her ears. Suddenly one morning, after a
powerful current had been applied, her hearing returned, but before
she came back for treatment the next day it had again left. The
electrical treatment was continued: each day the hearing stayed
longer and longer, and finally returned in full force and remained
good.
By hysterical paræsthesia is meant that form of perverted sensation

which is not distinctly depressed on the one hand or markedly
increased on the other. Under this head would come such conditions
as numbness, formications, prickling and tingling sensation, the
sensation of a ball in the throat or globus hystericus, etc. These
forms of perverted sensation are quite common among the
hysterical.
Hyperæsthesia may present itself in almost any locality, its areas of

distribution corresponding very well to those which have been given
for anæsthesia. Hyperæsthesia of the special senses is of especially
frequent occurrence. Great sensitiveness to sounds and to bright
lights or to particular colors is commonly observed. What might be
termed hysterical tinnitus aurium is met with occasionally.
Perversions of the senses of smell and taste are among the rarer
phenomena in the sensory sphere in hysteria. These may be of three
kinds: the senses may be completely obtunded; they may be
hyperacute; or they may show peculiar perversions. To some
individuals of the hysterical temperament certain smells are almost
unendurable, and these may be odors which to others are
particularly pleasant. In like manner, certain articles of food or drink
may be the source of great discomfort or absolute suffering. It is one
of the oldest of observations that hysterical and morbid cravings for
disagreeable or disgusting substances sometimes exist.
In one group of hysterias the presence of pain is the predominating

feature. Some of the situations in which hysterical pains are most
frequently felt are the head, the pericardial or left inframammary
region, over the stomach and spleen, the left iliac region, the region
of the kidneys, the sacrum, the hip, the spine, the larynx and
pharynx, one or both mammæ, or over the liver and the joints. Of
these locations, omitting the consideration of headache, the most
common seats of hysterical pain are the spine, the breasts and
inframammary region, the left iliac or ovarian region, the sacrum or
coccyx, and the joints.
Charles Fayette Taylor, in a brochure on sensation and pain,90 has

given a philosophical explanation of such pain, drawing largely from
Carpenter, Bain, Spencer, and others. The pith of the matter is that
many of our sensations are centrally initiated, the memory of
previous objective sensations. “Pain is different from ordinary
sensations, in that it requires an abnormal condition for its
production, and that it cannot be produced without that abnormal
condition. Hence it is impossible to remember pain, because the
apparatus does not exist for causing such a sensation as pain after
the fact or when it is to be remembered. Memory is a repetition, in
the nerve-centre, of energy which was first caused by the sensory
impulse from without. But centrally initiated sensations may be
mistaken, in consciousness, for pains depending wholly on a certain
intensity of excitability in the cerebral mass.”
90 Sensation and Pain, by Charles Fayette Taylor, M.D.—a lecture delivered before
the New York Academy of Sciences, March 21, 1881.
A large percentage of all cases of hysteria complain more or less of

spinal irritation. Spinal periostitis, spinal caries, and perhaps some
cases of spinal meningitis, are organic diseases which may give rise
to tenderness on pressure along the spine; but the majority of cases
of spinal irritation are found among neurasthenic or hysterical
patients. So much has already been written about spinal irritation
that much time need not be spent on the subject, were it not that
even yet many practitioners are inclined to regard cases as organic
spinal trouble because of the presence of great spinal tenderness,
whereas this symptom is almost diagnostic of the absence of real
spinal disease.
Painful diseases of the joints, especially in women, are not

infrequently hysterical or neuromimetic. Many such cases have been
reported. Taylor states, as the results of much carefully-guarded
experience, that hundreds of lame people are walking about
perfectly who do not know that they ought to limp, and that a much
larger number are either limping and walking on crutches, or not
walking at all, who have no affection whatever causing lameness.
Paget—and his experience accords with that of others—makes the

hip and knee, among the joints, the most frequent seats of nervous
mimicry as well as of real disease. According to him, mimicries in
other joints are almost too rare for counting; and yet in my first case
of this kind the pain was located in the shoulder. This case made a
lasting impression. The patient was a young lady of nervous
temperament, who came complaining of severe and continuous pain
in the left shoulder. No history of injury was given. The pain was said
to be rheumatic. Handling the arm and pressure round the joint
caused extreme pain. No heat, no redness, no swelling were
discoverable. The patient left me and went to a magnetic doctor, who
entirely dispelled the disorder on her first visit by gently stroking the
arm and shoulder. Another patient had been accidentally struck in
the knee. No swelling, heat, or other signs of inflammation followed
the accident, and did not afterward appear; but at intervals, for
several years, she complained of severe pain in and around this
joint. She would be for days, or it might be for weeks, without
speaking of the pain; and then again she would complain almost
incessantly, and would sometimes limp. These periods always
corresponded with times of mental and physical depression, and the
pain was evidently neuromimetic or hysterical.
The affection which has come down to us from ancient times under
the name of clavus hystericus is an acute boring pain confined to a
small point at the top of the head, and is sometimes described as
resembling the pain which would be produced by driving a nail into
the head; hence the term, from clavus, a nail. It may last for hours,
days, or even weeks. Instead of clavus hystericus, hemicrania,
occipital headache, or nape-aches may be present. On the whole,
aches and pains of the head in hysterical cases are more likely to be
localized to some point or area than to be general. Hysterical
patients, however, not infrequently complain of constricting,
contracting, or compressing sensations in the head.
In hysterical women the pulse is apt to be rapid, even sometimes

twenty, thirty, to fifty pulsations to the minute above normal. The
heart in these patients is irritable and prone to beat rapidly. One of
Mitchell's cases is worthy of brief detail: A neurasthenic, hysterical
woman, thirty-eight years old, when lying down had a heart-beat
never less than 130 per minute. Exertion added twenty or thirty
pulsations. Despite this irritability, however, the rhythm was good.
Ovarian pressure and pressure along the spine would suddenly
increase the heart-beats. Her temperature ranged from 95° in the
morning to 100° or 101.5° F. in the evening, although she had no
pulmonary or visceral trouble.
The high temperatures which have been observed in many cases of

hysteria have been due to some form of shrewd fraud; but Briand91
maintains with Gubler, Rigel, Dieulafoy, and others that the term
hysterical fever is correct, and he describes three forms of the fever:
(1) The slow continued fever of Briquet, characterized sometimes by
simple acceleration of the pulse, without elevation of temperature;
sometimes by a temperature rise, either with or without phenomena
or accompanied by headache, thirst, and other symptoms; (2) a
shorter form, always the result of a more or less active disturbance
of the nervous system by terror, fear, chagrin, and like causes; (3) a
form with intermittent febrile phenomena. Examples of the different
forms are given. Debove92 supports the view of the entity of the
hysterical fever, citing cases—one a woman twenty-four years old
who had, at intervals, marked fever, the temperature sometimes
reaching 1021/5° to 104° F. Malaria and tuberculosis were excluded.
Sulphate of quinia had no influence upon her attacks, but antipyrine
reduced the temperature and her general condition improved.
Debove has observed the temperature to rise from 1° to 2° F. by
mere suggestion when the patient was in a somnambulistic state.
91 Gazette hébdomadaire, quoted in Med. News, Dec. 1, 1883.
92 Ibid., quoted in Med. News, April 4, 1885.
On the other hand, it has been claimed that a true hysterical fever
never occurs or is extremely rare. Admitting this view, several
explanations may be given of the rise of temperature observed. It
may be due to intercurrent affections, as typhoid or intermittent fever,
or some local inflammatory disorder. It may be secondary fever, the
result of muscular effort or some similar cause. Lastly, and most
probably, it may be due to ingenious fraud, as to friction of the bulb,
pressure, or tapping with the finger, dipping the instrument into hot
water, connivance with the nurse, etc. Du Castel93 has reported a
trick of this kind. An hysterical girl, convalescent from an attack of
sore throat, displayed remarkable alternations of temperature. One
day the thermometer reached 163.4° F.! By carefully watching the
patient it was found she had learned the trick of lightly tapping the
end of the thermometer, which caused the mercury to ascend as far
as she wished. In the case of chronic hysterical insanity of which the
details have been given the temperature in the axilla on several
occasions reached 102°, 103°, and even 105° F.
93 Revue de Thérapeutique méd.-chir., No. xi., 1884.
Extreme states of pallor or blushing, sometimes in the extremities

and at others in the face, are mentioned by Mitchell as among the
vaso-motor disturbances of hysteria. Rosenthal gives a most
interesting observation with reference to vaso-motor conditions in
hysteria: the patient, a girl twenty-three years old, had epileptiform
attacks, which were preceded by a subjective sensation of cold and
discoloration of the hands and tips of the fingers. The hands became
very pale, the tips of the fingers and nails of a deep blue; the patient
experienced a disagreeable sensation of cold in the hands, and their
temperature sank more than 3°, while the pulse dropped from 72 to
65 or 66. After the attack the temperature rose 2° higher than the
normal condition; the fingers and nails became very red, and were
the seat of an abundant perspiration; the pulse increased to 84 or
88. Other interesting symptoms were present.
Mitchell94 has put on record three cases of hysteria in which was

present unilateral increase in bulk at or near the menstrual period,
and also at other seasons after emotional excitement. He does not
give any opinion as to its nature, but believes that it is not a mere
increase of areolar serum, and that it does not appear to resemble
the vasal paralysis in which the leg throbs and exhibits a rise in
temperature and tint. He is unable also to identify it with any form of
lymph œdema which it resembles, for in this disorder there is more
obvious œdema, and it is also quite permanent. Whatever the cause
of the swelling, he believes that it is under the influence of the
nervous system, and that it varies with the causes which produce
analgesia or spasm. I have seen swelling of this kind in several
cases, and have probably overlooked it in others. In one of my
reported cases of hystero-epilepsy it was a very marked symptom,
coming and going, increasing and diminishing, with other symptoms.
94 American Journal of the Medical Sciences, New Series, vol. lxxxviii., July, 1884, p.
94.
Buzzard calls attention to the fact that in many cases belonging to

the class of hysteria the epidermis, which has arrived at
extraordinary thickness, apparently from disuse of the limbs, offers
great resistance to the passage of electric currents. Under these
circumstances a more than usual amount of care in thoroughly
soaking and rubbing the skin, as well as in selecting the motor
points, is necessary to avoid fallacies. Absence of reflex from the
sole of the foot, according to the same authority, is a very constant
symptom in hysterical paraplegia.
Some wasting does not negative the idea of hysteria, but this
wasting a not associated with changing the electrical reaction.
Disturbance of the secretion of the urine is among the most frequent

of the minor hysterical troubles, and has often been noted by writers
upon this subject since a very early date. Sydenham95 says that of
the “symptoms accompanying this disease, the most peculiar and
general one is the making great quantities of urine as clear as rock-
water, which upon diligent inquiry I find to be the distinguishing sign
of those disorders which we call hypochondriac in men and hysteric
in women. And I have sometimes observed in men that soon after
having made urine of an amber color, being suddenly seized with
some disturbance of mind, they made a large quantity of clear water,
with a continued violent stream, and remained indisposed till the
urine came to its former color, when the fit went off.” This symptom
shows itself as strikingly in the hysteria of the present day as in the
age of Sydenham.
95 Op. cit.
A complete anuria or ischuria is one of the older observations in
hysteria. Laycock, Charcot, and many others have written at length
on this subject. Finch96 has published a curious case of complete
anuria. The patient had various hysterical symptoms, including
paroxysms with unconsciousness, contracture, also vomiting.
Micturition and defecation were entirely suspended (?) from Dec. 24,
1877, to Feb. 22d of the following year. During a period of fifty-eight
days paroxysms were frequent; but on using the catheter the bladder
was always found empty. The probability of hysterical fraud is very
great in this case. A few case of hysterical retention of the urine in
men have been reported.
96 Nice médicale.
Increase of the uterine and vaginal secretions is mentioned by Jolly

as sometimes attributable to nervous influences in cases of hysteria.
He mentions the case of a woman suffering from hysterical
symptoms at the change of life whose disposition was decidedly
depressed; though at times lively, particularly erotic. In this case
simultaneously with tympanites appeared a thin, clear fluor albus.
Local treatment with quiet had no decided effect, but it disappeared
with the tympanites when the patient was excited by the visit of a
sister who overwhelmed her with reproaches.
Hysterical vomiting of food sometimes persists for weeks; strangely

enough, the patients usually appear to suffer little in consequence.
Chambers believes that the articles swallowed do not all get into the
stomach. The phenomena of rejection in these cases are similar to
those of an œsophageal stricture; some of the matter swallowed is
really retained, and therefore the patient will not starve as soon as
might be supposed.
Two cases of simulated pregnancy by hysterical women have come

under my observation. Cases are reported also in which hysteria
simulated closely the process of natural labor, as one for instance,
by Hodges.97 A woman said to be in the fifth month of pregnancy
engaged him to attend her at term. Four months afterward he was
sent for, the patient having severe pains, supposing herself to be in
labor. On examination, however, a tumor present turned out to be the
bladder distended and prolapsed. Sparks98 reports the case of a
young married woman who had the symptoms of the third stage of
labor, the case being purely hysterical.
97 Lancet, 1859, ii. 619.
98 Chicago Med. Journ. and Examiner, 1880.
Walker99 reports a group of hysterical symptoms closely simulating

the prodromes of puerperal eclampsia. The patient, a married
woman only eighteen years old, when pregnant six months lifted a
tub of water, rupturing the membranes. In the eighth month, after she
had remained in bed three days, she began to complain of severe
headache; soon she said she was blind; the pupils of the eye were
neither dilated nor contracted, and responded sluggishly to light.
Ophthalmoscopic examination gave negative results, but she did not
flinch from the light of the mirror. Temperature, pulse, and respiration
were about normal. The urine contained no albumen. She recovered
her sight in twelve hours, and had no continuing trouble.
99 Arch. of Medicine, New York, 1883, x. 85-88.
Paget mentions cases of phantom tumor occurring in the calf, thigh,

and breast. These phantoms shift from one place to another, or
disappear when the muscles are relaxed by anæsthetics or
otherwise. The nervous mimicry of aneurisms (of Paget) are what
Laycock and others treat of as pulsations. They are most frequent in
the carotid artery and abdominal aorta. Of imitations of cancer it
need only be said that the average hysterical female suspects every
lump in the breast and elsewhere to be a cancer.
Mitchell mentions certain peculiar symptoms quite common among

hysterical women, but which also occur, but more rarely, among
men. When falling asleep these patients have something like an aura
rising from the feet and going up toward the head. One patient had
an aura which passed upward from his feet, and when it had
reached his head he felt what he described as an explosion. Another
had a sensation as though something was about to happen, but no
distinct ascending aura. If he roused himself in time, he could by
turning over release himself from the sensation and break the chain
of morbid events. At the close of the attack he had a noise in his
head—something like the sound of a bell which had been struck
once. Other patients when going to sleep have constant sounds,
faint usually and rarely loud and without a feeling of terror. Most of
the patients were women worn out or tired out and hysterical.
Sometimes hysterical women awake with numbness and tingling,

which rapidly passes away or yields to a little surface friction. Some
persons who have in a measure recovered from hemiplegia of
organic origin are liable to awake out of sleep with a numbness and
lessening of power on the side once palsied. Palpitation of the heart,
vertigo, and a certain fear of a respiratory character are among the
milder forms of trouble which Mitchell mentions as haunting the
sleep of nervous or hysterical women.
Under hysteria some of the affections, more common among men

than women, known as railway brain, railway spine, etc., may be
classified. These disorders might be termed traumatic hysteria. The
amount of money that has been paid out by corporations, beneficial
societies or individuals because of suits or threatened suits for
damages in cases of railway or other accidents is something almost
incredible. At least two classes of cases, besides those of
recognizable gross lesion, are to be found in the ranks of those
claiming such damages. These are first the bogus cases or
malingerers, and secondly cases of nervous mimicry. An hysterical
individual who has been in a railway collision, or has been the victim
of an accident for which somebody else may possibly be made
responsible, may deliberately practise fraud, or he may consciously
or unconsciously imitate or exaggerate real symptoms of serious
import. Sometimes there may be in the same case a mingling of real
and of simulated or of neuromimetic disorders. As long as a claim of
damages in this class of cases exists, great care should be taken in
making a diagnosis. The neuromimetic cases, however, do occur,
particularly in the hysterical and neurasthenic, without any reference
to litigation.
A lady fell off her chair backward. She was not rendered
unconscious, but became nervous, and began to have considerable
pain and soreness in the sacral region and about the right sacro-iliac
juncture. She had no palsy, nor spasm, nor anæsthesia, nor
paræsthesia, and had no difficulty in her bladder, but nevertheless
was helpless in bed for many weeks, supposing herself unable to
stand. She recovered promptly, under treatment with electricity, as
soon as a favorable prognosis was given in a very positive manner.
A man fell on the ice and struck his back, but was able to go on with
his usual occupation, although complaining of his limbs. Two months
afterward, while recovering from typhoid fever, he fell from a chair,
and was unable to raise himself, and found that he had lost control of
his legs and arms. During the attack he was not unconscious. He
was bed-ridden for two months, but did not lose control of his
bladder and bowels. He was put on his feet by a little treatment and
much encouragement.
A woman was badly pushed about while riding in a street-car by the

car being thrown off the track. She miscarried in about six weeks,
flooding a good deal after injury to the time of miscarriage. Later,
spinal symptoms began. She had extensive pain and tenderness at
the lower end of the spine. She sometimes fainted. Examination
revealed general spinal tenderness, much more marked in the sacro-
coccygeal region. She was pale, anæmic, and neurasthenic. She
brought suit against the railway company for damages, which were
very properly awarded, as the miscarriage, hemorrhage, and
consequent anæmia were without doubt the result of an accident for
which she was in no wise responsible. Some organic spinal-cord
disease, however, was supposed to exist, the chief foundation for
this view being the extreme spinal tenderness, which was hysterical.
Finally, some hysterical cases present a succession of local

hysterical phenomena following each other more or less rapidly. One
symptom seems to take possession of the patient for the time being,

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Carnivoran Ecology : The Evolution and

Function of Communities Steven W.

importance of carnivorans in future communities. References cited

1 Introduction to Carnivoran Ecology 1

3 Evolution and historical biogeography 29

3.3 Early carnivorans 31

5 Sensory biology and neuroanatomy 71

6.3 Disease ecology 92

7 Interactions with non-prey animals 103

8 Interactions with prey 127

9.2 Trophic cascades 157

10 Population ecology 173

11 How carnivorans affect humans 193

12 How humans affect carnivorans 219

12.6 Effects on behavior 227

Appendix I List of extant carnivoran species 251

Appendix II List of non-carnivoran species mentioned 257

Introduction to Carnivoran Ecology

Figure 1.4 Venn diagram of the

Figure 1.5 Farmed black-phase red

Figure 2.1 continued

Box 2.1 Filter-feeding carnivorans

No. Amer. martens

carnivorans rotate the radius well, consistent with 2.2.3 Climbing

predation, injuries from short falls, and crushing

2.3 Other adaptations to aquatic living

600 Figure 2.7 Hair density of mammalian

Figure 2.8 Buoyancy is a critical feature

References Fisher, R.E. (2011) “Red panda anatomy,” in Glatston, A.R.

Evolution and historical biogeography

Eupleridae founding event

Richardson81 records the case of a young lady who saw in India a

Some of the most remarkable cases of hysterical contracture are

Many forms of hysterical local spasms occur. Hysterical strabismus

Spasm of the pharynx, larynx, and œsophagus have been separated

Hysterical dysphagia, which is usually spasmodic, is sometimes a

Of the so-called hysterical asthma or hysterical breathing I have

Coates,84 speaking of hysterical or nervous breathing, gives the

Vaginismus, or spasm of the vagina, may with propriety be regarded

The sensorial affections of hysteria can be classified according either

Anæsthesia is one of the most frequent of hysterical phenomena, but

In 400 hysterical cases Briquet found 240 positive examples of

Hysterical anæsthesia, may be of various forms, according to the

General anæsthesia is extremely rare. No example of it has ever

Hemianæsthesia has in recent years received much attention from

Much attention has been paid to the study of hemianæsthesia by

Anæsthesia of mucous membrane is an old observation. It may

A striking characteristic of hysteroid sensory disorders of the

The term achromatopsia is due to Galezowski. Hysterical

Hysterical blindness and achromatopsia have been well studied by

87 “Simulated Amaurosis,” by George C. Harlan, M.D., American Journal of Medical

In several cases of hystero-epilepsy under my care both amblyopia

C. H. Thomas of Philadelphia has given me the particulars of a case

What might be termed hysterical dilatation of the pupil is sometimes

A noticeable feature in all the cases under consideration was the

The following case has been kindly furnished to me by Charles S.

By hysterical paræsthesia is meant that form of perverted sensation

Hyperæsthesia may present itself in almost any locality, its areas of

In one group of hysterias the presence of pain is the predominating