Species New to Science: Journal: Palaeontology

Showing posts with label Journal: Palaeontology. Show all posts

Friday, April 4, 2025

[PaleoMammalogy • 2025] Down to Earth: Therian Mammals became more Terrestrial towards the End of the Cretaceous

Dryolestes, a Late Jurassic relative of the Cretaceous therians

in Janis, Martín-Serra, Theodor et Scott, 2025.

DOI: doi.org/10.1111/pala.70004

Artwork by James Brown.

Abstract

The end Cretaceous extinctions had a profound effect on mammalian diversity, especially on metatherians (marsupials and their extinct relatives). Could mammalian substrate preference have influenced differential survival patterns? The plant fossil record shows changing angiosperm leaf anatomy during the last ten million years of the Cretaceous that would have resulted in a greater richness of terrestrial understory habitats, and work by other researchers implies that terrestrial (vs arboreal) substrate preference promoted increased survival over the Cretaceous–Palaeogene boundary for both mammals and birds. Here we use fragmentary postcranial remains of Late Cretaceous mammals and show that, at least in the Western Interior of North America, therian mammals were becoming more terrestrial in their locomotor mode towards the end of the Cretaceous.

Keywords: Mesozoic mammal, postcranial anatomy, locomotor mode, Cretaceous habitat, end Cretaceous extinction

Dryolestes (left) and Haldanodon (right), two creatures from the Late Jurassic period,

Digital reconstruction by James Brown, in consultation Pamela G. Gill.

Dryolestes, a Late Jurassic relative of the Cretaceous therians.

Artwork by James Brown. Pamela Gill

Christine M. Janis, Alberto Martín-Serra, Jessica M. Theodor and Craig S. Scott. 2025. Down to Earth: Therian Mammals became more Terrestrial towards the End of the Cretaceous. Palaeontology. DOI: doi.org/10.1111/pala.70004 [01 April 2025]

Researchers unlock life secrets of Jurassic mammals using X-ray imaging

https://www.southampton.ac.uk/biosci/news/2024/08/researchers-unlock-life-secrets-of-jurassic-mammals-using-xray-imaging.page

Wednesday, November 8, 2023

[PaleoIchthyology • 2023] Dasyomyliobatis thomyorkei (Chondrichthyes: Myliobatiformes) • The Evolutionary Origin of the durophagous Pelagic Stingray Ecomorph

Dasyomyliobatis thomyorkei

Marramà, Villalobos-Segura, Zorzin, Kriwet & Carnevale, 2023

DOI: 10.1111/pala.12669

Artworks by Fabrizio Lavezzi.

Abstract

Studies of the origin of evolutionary novelties (novel traits, feeding modes, behaviours, ecological niches, etc.) have considered a number of taxa experimenting with new body plans, allowing them to occupy new habitats and exploit new trophic resources. In the marine realm, colonization of pelagic environments by marine fishes occurred recurrently through time. Stingrays (Myliobatiformes) are a diverse clade of batoid fishes commonly known to possess venomous tail stings. Current hypotheses suggest that stingrays experimented with a transition from a benthic to a pelagic/benthopelagic habitat coupled with a transition from a non-durophagous diet to extreme durophagy. However, there is no study detailing macroevolutionary patterns to understand how and when habitat shift and feeding specialization arose along their evolutionary history. A new exquisitely preserved fossil stingray from the Eocene Konservat-Lagerstätte of Bolca (Italy) exhibits a unique mosaic of plesiomorphic features of the rajobenthic ecomorph, and derived traits of aquilopelagic taxa, that helps to clarify the evolutionary origin of durophagy and pelagic lifestyle in stingrays. A scenario of early evolution of the aquilopelagic ecomorph is proposed based on new data, and the possible adaptive meaning of the observed evolutionary changes is discussed. The body plan of †Dasyomyliobatis thomyorkei gen. et sp. nov. is intermediate between the rajobenthic and more derived aquilopelagic stingrays, supporting its stem phylogenetic position and the hypothesis that the aquilopelagic body plan arose in association with the evolution of durophagy and pelagic lifestyle from a benthic, soft-prey feeder ancestor.

Keywords: durophagy, ecomorph, evolution, Myliobatiformes, pelagic lifestyle, stingray

†Dasyomyliobatis thomyorkei gen. et sp. nov. from the Eocene of Monte Bolca (Italy).
MCSNV VR.21.107, holotype, dorsoventral view natural normal light.

†Dasyomyliobatis thomyorkei gen. et sp. nov. (MCSNV VR.21.107, holotype) showing its peculiar combination of rajobenthic (A–D) and aquilopelagic (E–H) traits:
A, small holaulacorhizous lateral teeth arranged in alternating rows; B, pectoral-fin radials with catenated calcification and no cross-bracing; C, free tail vertebrae without cartilaginous rod and caudal fin reduced to a ventral fold; D, soft, flexible pectoral disc with convex anterior and posterior margins; E, head protruding from pectoral disc; F, cephalic lobes; G, wing-like pectoral disc with positive FRD; H, enlarged hexagonal symphyseal/parasymphyseal polyaulacorhizous teeth in pavement-like arrangement. Scale bar represents 100 mm.

SYSTEMATIC PALAEONTOLOGY

Class CHONDRICHTHYES Huxley, 1880

Superorder BATOIDEA Compagno, 1973

Order MYLIOBATIFORMES Compagno, 1973

Family †DASYOMYLIOBATIDAE nov.

Genus †DASYOMYLIOBATIS nov.

Type species: †Dasyomyliobatis thomyorkei sp. nov.

Derivation of names: Genus and family names refer to the peculiar mosaic of dasyatoid and myliobatoid traits.

†Dasyomyliobatis thomyorkei sp. nov.

Derivation of name: After the British composer and musician Thom Yorke.

Holotype: MCSNV VR.21.107/8 well preserved, complete, and articulated skeleton in part and counterpart, 99.9 cm disc width.

Type locality & horizon: Pesciara site, Bolca Konservat-Lagerstätte, Italy; early Eocene, late Ypresian, middle Cuisian, SBZ-11, †Alveolina dainelli Zone, c. 50 Ma (Papazzoni et al. 2014).

Diagnosis: Stingray unique in having a peculiar combination of dasyatoid and myliobatoid traits. Like dasyatoids, †Dasyomyliobatis has a soft and flexible pectoral disc with convex anterior and posterior fin margins supported by catenated radials with no cross-bracing; numerous (c. 40) labiolingually directed files of holaulacorhizous lateral teeth arranged in alternating rows; tail formed by free vertebrae not stiffened by a cartilaginous rod; caudal fin reduced to a ventral fold. Like myliobatoids, †Dasyomyliobatis shows a head protruding anterior to a wing-like pectoral disc; cephalic lobes contacting along their mesial edge forming a single, shovel-like structure; cephalic-lobe radials discontinuous with pectoral-fin radials; moderately enlarged hexagonal symphyseal/parasymphyseal polyaulacorhizous teeth in pavement-like arrangement, with bulbous/irregular interlocking mechanism, 3–4 wide-block and irregularly spaced root lobes. In addition, †Dasyomyliobatis has a pectoral-fin AR between 2.0 and 3.0, and positive FRD.

Hypothetical reconstruction of †Dasyomyliobatis thomyorkei gen. et sp. nov. in different views.

Artwork by Fabrizio Lavezzi.

Life reconstruction of †Dasyomyliobatis thomyorkei gen. et sp. nov. swimming in the marine tropical shallow waters of the western Tethys about 50 million years ago.

Artwork by Fabrizio Lavezzi.

CONCLUSIONS:

The unique body plan of †Dasyomyliobatis suggests that:

• †Dasyomyliobatis is a representative of a new stingray family with unique hybrid dentition and pectoral-fin morphology that allowed the shift from undulatory to oscillatory swimming, and to exploit a variety of prey (from soft-bodied to hard-shelled organisms).

• The evolutionary origin of durophagy and pelagic lifestyle was achieved through gradual transformation of morphological traits at least since the early Late Cretaceous.

• Cephalic lobes were already present in a stingray without crustal calcification, cross-bracing, or compagibus laminam corroborating the hypothesis that they originated before the shift toward exclusive oscillatory locomotion and occupation of pelagic environments.

• The phylogenetic analyses highlight that evolutionary modifications of the dentition related to a shift toward extreme durophagy seem to covariate with the evolution of traits of pectoral skeleton related to a shift toward a pelagic lifestyle, possibly reflecting high level of integration. One can speculate that although invasion of new habitats allowed initially stingrays to exploit wider ranges of food items, competition with other benthic batoids like skates, known to occupy today the same niche as benthic stingrays in deeper and cooler waters (Ebert & Compagno 2007) but also warm and shallow waters during the Late Cretaceous (Cappetta 1980), pushed pelagic/benthopelagic stingrays to specialize for a less exploited food resource, like hard-shelled invertebrates, although this hypothesis needs to be tested.

Giuseppe Marramà, Eduardo Villalobos-Segura, Roberto Zorzin, Jürgen Kriwet and Giorgio Carnevale. 2023. The Evolutionary Origin of the durophagous Pelagic Stingray Ecomorph. Palaeontology. DOI: 10.1111/pala.12669

Friday, June 9, 2023

[Paleontology • 2023] Bentonyx sidensis • Unique Dentition of rhynchosaurs (Archosauromorpha: Rhynchosauria) and their Two-phase Success as Herbivores in the Triassic

Bentonyx sidensis Langer, Montefeltro, Hone, Whatley & Schultz, 2010

in Sethapanichsakul, Coram & Benton, 2023.

DOI: 10.1111/pala.12654

Abstract

Rhynchosaurs were key herbivores over much of the world in the Middle and Late Triassic, often dominating their faunas ecologically, and much of their success may relate to their dentition. They show the unique ankylothecodont mode of tooth implantation, with deep roots embedded in the bone of the jaw and low crowns that were rapidly worn down in use. During growth, the main area of oral food processing, located in the middle and posterior portions of the occlusal surfaces of the jaws, moved posteriorly relative to the anterior tips of the jaws, which curved up. As the maxilla and dentary grew by addition of new bone posteriorly, the dental lamina fed in new teeth at the back of the tooth rows. CT scanning of the holotype skull of Bentonyx sidensis from the Middle Triassic of England reveals previously concealed details of the dentition. Together with new dentary material from the same location, this has enabled us to examine the tooth replacement process and elucidate ontogenetic changes in dentition and jaw morphology as the animals aged. There were major changes in rhynchosaur anatomy and function through their evolutionary history, with the early forms of the Middle Triassic dying out before or during the Carnian Pluvial Episode (233–232 Ma), and the subclade Hyperodapedontinae, with broad skulls and adaptations to chop tough vegetation, subsequently diversifying worldwide in a successful ecological expansion until their global extinction 227–225 Ma.

Keywords: dentition, rhynchosaur, tooth replacement, herbivory, Triassic, Carnian Pluvial Episode

Bentonyx sidensis

Thitiwoot Sethapanichsakul, Robert A. Coram and Michael J. Benton. 2023. Unique Dentition of rhynchosaurs and their Two-phase Success as Herbivores in the Triassic. Palaeontology. 66(3); e12654. DOI: 10.1111/pala.12654

Tuesday, May 18, 2021

[Paleontology • 2021] Parioscorpio venator • Stranger than A Scorpion: A Reassessment of A problematic Arthropod from the Llandoverian Waukesha Lagerstätte, Wisconsin, USA

Parioscorpio venator Wendruff, Babcock, Wirkner, Kluessendorf & Mikulic, 2020

in Anderson, Schiffbauer, Jacquet, ... et Mikulic, 2021.

DOI: 10.1111/pala.12534

twitter.com/FossilDetective

2020. DOI: 10.1038/s41598-019-56010-z

Abstract

A relatively uncommon arthropod of the Waukesha lagerstätte, Parioscorpio venator, is redescribed as an arthropod bearing a combination of characters that defy ready classification. Diagnostic features include sub‐chelate ‘great appendages’, a lack of antennae, multiramous anterior trunk appendages, filamentous fan‐like rear trunk appendages, and apparently thin and poorly preserved pleural fields. Phylogenetic analysis resolves this organism as basal to crown‐group Mandibulata and Chelicerata, but its exact placement is inconclusive. Thus, we compare its morphology to several stem groups of arthropods in a discussion of its plausible taxonomic affinities. The examined specimens are probably carcasses and preserve a variety of soft‐tissue details, including muscle blocks in the head, eyes and eye facets, likely ventral nerve cords, a central gut tract and trunk legs with multiple filamentous elements organized into stiff bundles. The preservation habits of P. venator are characterized and compared to previous assessments of Waukesha lagerstätte taxa. Four preservation habits are observed: a phosphatized habit showing flattened to partly three‐dimensional mineralization in francolite; a mouldic habit largely left behind by removed francolite that shows no carbon enrichment despite a darkened colour; sheet‐like or speckled carbonaceous compressions; and scattered pyrite crystals. This redescription highlights both the palaeobiological value of ‘small’ lagerstätten typical of the middle Palaeozoic and the caution that must be taken when interpreting their more enigmatic constituents.

Keywords: stem‐group Arthropoda, taphonomy, phosphatization, nerve cord, appendage, morphology, tagma

Specimens upon which the rediagnosis and redescription of Parioscorpio venator Wendruff et al., 2020 are primarily based.
A, UWGM2793, a nearly complete specimen with an entire left great appendage. B, UWGM2785, a specimen with all cephalic appendages intact, including both great appendages, which are nearly complete; note that the posterior portion of the body is still buried beneath the matrix. C, UWGM2764, paratype and counterpart to UWGM2163, preserved as a thin film with the right great appendage barely visible on the upper right; no trunk appendages are preserved, which makes the posterior constriction of the axial trunk easy to see compared to other specimens. D–E, part and counterpart of UWGM2857, a nearly complete specimen with numerous head and trunk details.

F–G, part and counterpart of UWGM2854, which preserves many three‐dimensional limbs, but whose head is cut off by the border of the matrix. H, UWGM2798, a largely mouldic specimen showing excellent preservation of the cephalic appendages, including two complete great appendages. I–J, part and counterpart of UWGM2885, a nearly complete specimen which shows limited three‐dimensional preservation, but preserves many walking legs as dark compressions. All scale bars represent 5 mm.

Reconstructions of the morphology of Parioscorpio venator.
A, whole body, from a three‐quarters dorsal view; note that the limbs can be seen through the thin, translucent tergopleural cuticle; the tentative preservation of the tergopleurae in most specimens raises this possibility. B, focus on the great appendage and second cephalic appendage and their attachment to the head; the reconstruction shows slight lateral displacement of the limbs to better envision their bases; note that the sclerotized portion of the first article of the great appendage is contained within a translucent membrane. C, illustration showing our reconstruction of a standard trunk limb; limb rami are labelled in roman (with alternative interpretations in smaller font), while individual filamentous bundles on the endopod and endopodal exite/exopod are labelled in italics; the exact proportions of the limb components vary based on the limb's placement on the body; this illustrated limb, with the racemose filamentous bundle considerably longer than the exopod/epipod or the walking portion of the endopod, is from the middle of the trunk.

twitter.com/FossilDetective

Evan P. Anderson, James D. Schiffbauer, Sarah M. Jacquet, James C. Lamsdell, Joanne Kluessendorf and Donald G. Mikulic. 2021. Stranger than A Scorpion: A Reassessment of Parioscorpio venator, A problematic Arthropod from the Llandoverian Waukesha Lagerstätte. Palaeontology. DOI: 10.1111/pala.12534

twitter.com/FossilDetective/status/1384488772331573249

Genus Parioscorpio gen. nov.

Etymology. From Latin, pario, progenitor, and scorpio, scorpion.

Parioscorpio venator gen. et sp. nov.

Etymology. From Latin, venator, hunter.

Types. Holotype, University of Wisconsin Geology Museum, Madison, Wisconsin, UWGM 2162. Paratype, UWGM 2163. Location. Waukesha Lime and Stone Company west quarry, north of State Highway 164, Waukesha, Wisconsin, USA.

Horizon. Lower part of the Brandon Bridge Formation (Silurian: Llandovery, Telychian).

Andrew J. Wendruff, Loren E. Babcock, Christian S. Wirkner, Joanne Kluessendorf and Donald G. Mikulic. 2020. A Silurian ancestral scorpion with fossilised internal anatomy illustrating a pathway to arachnid terrestrialisation. Scientific Reports. 10: 14. DOI: 10.1038/s41598-019-56010-z

Friday, April 28, 2017

[Paleontology • 2017] A New Phylogeny of Stegosauria (Dinosauria, Ornithischia)

DOI: 10.1111/pala.12291

Abstract

The stegosaurs are some of the most easily recognizable dinosaurs, but are surprisingly rare as fossils. Consequently much remains unknown about their palaeobiology, and every new stegosaurian find contributes to our understanding of the evolution of the clade. Since the last attempt to examine the evolutionary relationships of Stegosauria, new specimens have come to light, including the most complete individual of Stegosaurus ever found, new taxa have been described and, perhaps most importantly, new methods for analysis of cladistic datasets have been produced. In the light of these new data and technological advances, the phylogenetic relationships of the stegosaurs and basal armoured dinosaurs are investigated. The inclusion of continuous data results in much better resolution than was previously obtained, and the resulting single most parsimonious tree supports re-erection of the genera Miragaia and Hesperosaurus, which had previously been synonymized with Dacentrurus and Stegosaurus respectively. The recently described genus Alcovasaurus is resolved as a basal thyreophoran, but this is most likely a consequence of a very high degree of missing data and the questionable ontogenetic stage of the specimen. Examination of the effects of continuous data on the analysis suggest that while it contains a phylogenetic signal congruent with that of discrete data and provides better resolution than discrete data alone, it can affect topologies in unpredictable ways, particularly in areas of the tree where there are large amounts of missing data. The phylogeny presented here will form the basis for future work on the palaeobiology of the plated dinosaurs.

Illustration: Davide Bonadonna

Thomas J. Raven and Susannah C. R. Maidment. 2017. A New Phylogeny of Stegosauria (Dinosauria, Ornithischia). Palaeontology. 60(3); 401–408. DOI: 10.1111/pala.12291

twitter.com/ThePalAss/status/854257910276292608

Saturday, April 18, 2015

[Paleontology • 2015] Pelagic Neonatal Fossils support Viviparity and Precocial Life History of Cretaceous Mosasaurs

Figure 4. Clidastes liodontus giving live birth in an open pelagic setting ~85 million years ago,
beneath the shadow of the toothed stem bird Ichthyornis.

Artist's interpretation of this study's principal conclusions || Illustration by Julius Csotonyi.

DOI: 10.1111/pala.12165

Abstract

Mosasaurs were large marine squamates that inhabited all of the world's oceans during the Late Cretaceous. Their success as apex predators has been attributed to their rapid acquisition of aquatic adaptations, which allowed them to become fully pelagic. However, little is known about the breeding biology of derived, flipper-bearing mosasaurs, as the record of neonatal mosasaur fossils is extremely sparse. Here, we report on the fragmentary cranial remains of two neonatal mosasaurs from the Niobrara Formation, referred to Clidastes sp. Comparison with other preliminary reports of neonatal mosasaurs reveals that these specimens are among the smallest individuals ever found and certainly represent the smallest known Clidastes specimens. The recovery of these extremely young specimens from a pelagic setting indicates that even neonatal mosasaurs occupied open oceanic habitats and were likely born in this setting. These data shed new light on the ecology of neonatal mosasaurs and illustrate the degree to which size-related taphonomic and collection biases have influenced our understanding of the early life history of these iconic marine reptiles.

Keywords: mosasaur; viviparity; Niobrara; marine reptile; life history

Figure 1. The smallest mosasaurid remains from the Niobrara Formation, previously misidentified as toothed stem birds.
A, lateral and dorsal view of the left dentary of Clidastes, YPM VP.058125; lateral and dorsal view of the left dentary of Clidastes, YPM VP.058126. Scale bar represents 1 cm. B, size comparison of several of the smallest Clidastes dentaries from the Niobrara Formation, in lateral (left) and dorsal (right) views. Scale bar represents 1 cm. The newly discovered specimens reported here (YPM 058125, YPM 058126) are by far the smallest. C, comparison of maximum tooth diameters for juvenile Clidastes from the Niobrara chalk. The newly discovered specimens (YPM VP.058125, YPM VP.058126) represent the smallest mosasaurids known from the Niobrara Formation and are currently the youngest Clidastes specimens ever found. D, estimated body length of neonatal mosasaurs (YPM VP.058125 and YPM VP.058126) relative to an adult specimen of Clidastes liodontus. The adult is 3 m in length; the neonate is 0.66 m in length (see text).

Redrawn from Caldwell and Diedrich (2005, fig. 5) and Lindgren et al. (2011, fig. 12). Scale bar represents 1 m. Colour online. DOI: 10.1111/pala.12165

Daniel J. Field, Aaron LeBlanc, Adrienne Gau and Adam D. Behlke. 2015. Pelagic Neonatal Fossils support Viviparity and Precocial Life History of Cretaceous Mosasaurs. Palaeontology. DOI: 10.1111/pala.12165

http://news.yale.edu/2015/04/10/new-beginning-baby-mosasaurs-thanks-yale-research

Thursday, January 9, 2014

[Paleontology / Invertebrate • 2013] Kachinophilus pereirai • Geophilomorph Centipedes from the Cretaceous Amber of Myanmar (Burma)

Figure 1. Kachinophilus pereirai gen. nov. sp. nov.
A–B, holotype AMNH Bu-Ba41a, male, complete body, dorsal (A) and ventral (B) views.
C, paratype AMNH Bu-Ba50a, sex unknown, complete body, dorsal view.
D, paratype AMNH Bu-Ba63a, sex unknown, incomplete body (only anterior part), ventral view.

All scales 1 mm. Abbreviations: an, antenna; fo, forcipule; le-1, leg of the first pair;
le-u, leg of the ultimate pair. DOI: dx.doi.org/10.1111/pala.12051

ABSTRACT
The only previously known Mesozoic fossils of the chilopod order Geophilomorpha are two species from the Late Jurassic and Late Cretaceous, both known from single specimens that cannot be assigned with precision to a family. Four specimens from the Late Cretaceous (earliest Cenomanian) amber of Burma include three that can be identified as conspecific, described here as Kachinophilus pereirai gen. nov. sp. nov. These specimens preserve greater morphological detail in comparison with other fossil geophilomorphs: the form and fine features of the head, the maxillary complex, the trunk sternites with associated glandular pores and the ultimate pair of legs defend the assignment of the species to the extant family Geophilidae, and most probably to a derived subgroup including well-known extant genera such as Ribautia Brölemann, 1909. Confocal laser scanning microscopy supplements examination under incident and transmitted light to document details of high taxonomic relevance in the head and the forcipular segment. The modern appearance of this species and its membership among deeply nested extant clades are consistent with molecular estimates that most of the diversity of crown-group Geophilomorpha originated before the Late Cretaceous.

Keywords: Geophilidae; Cenomanian; Kachinophilus; evolutionarily conserved morphology

Order GEOPHILOMORPHA Pocock, 1895
Family GEOPHILIDAE Leach, 1815

Genus KACHINOPHILUS gen. nov.
Type species: Kachinophilus pereirai sp. nov.

Derivation of name: Compounding the geographical source of the fossils (Kachin, Burma) and the frequent geophilomorph generic termination – philus.
; pereirai -- for our colleague Luis A. Pereira (Museo de La Plata, Argentina), in recognition of his exemplary systematic work on Geophilomorpha.

Lucio Bonato, Gregory D. Edgecombe, Alessandro Minelli. 2013. Geophilomorph Centipedes from the Cretaceous amber of Burma. Palaeontology. DOI: dx.doi.org/10.1111/pala.12051

http://researchgate.net/publication/259554775_Geophilomorph_centipedes_from_the_Cretaceous_amber_of_Burma