TAXONOMIC NOMENCLATURE

1. Objectives:
At the end of the module the students will be able to:
 describe the Linnaean system of classification;
 classify organisms into a hierarchy; and
 construct and use dichotomous keys for identification.

2. Topic Outline
 Some Early Taxonomists
 Linnaean Systems of Classification
 Binomial Nomenclature
 Classifying Organisms Based on Similar and Distinct Characters
 The Dichotomous Key

3. Pre-Assessment
Direction: Choose the letter that corresponds to the word or phrase that best
completes the sentence.

1. In a comparison of birds and mammals, the condition of having four limbs is

a. a shared ancestral character.
b. a shared derived character.
c. a character useful for distinguishing birds from mammals.
d. an example of analogy rather than homology.

2. Based on the tree below, which statement is not correct?

a. The salamander lineage is a basal taxon.

b. Salamanders are a sister group to the group containing lizards, goats, and
humans.
c. Salamanders are closely related to goats as to humans.
d. Lizards are more closely related to salamanders than to humans.

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3. The various taxonomic levels (namely, genera, classes, etc.) of the hierarchical
classification system differ from each other on the basis of

a. how widely the organisms assigned to each are distributed throughout the
environment.
b. their inclusiveness.
c. the relative genome sizes of the organisms assigned to each.
d. morphological characters that are applicable to all organisms.

4. If organisms A, B, and C belong to the same class but to different orders and if
organisms D, E, and F belong to the same order but to different families, which of the
following pairs of organisms would be expected to show the greatest degree of
structural homology?

a. A and B
b. A and C
c. B and D
d. D and F

5. Linnaeus was a "fixist" who believed that species remained fixed in the form in
which they had been created. Linnaeus would have been uncomfortable with
a. classifying organisms using the morphospecies concept.
b. the scientific discipline known as taxonomy.
c. phylogenies.
d. nested, ever-more inclusive categories of organisms.
e. a hierarchical classification scheme.

6. The term homoplasy is most applicable to which of the following features?

a. the legless condition found in various lineages of extant lizards
b. the five-digit condition of human hands and bat wings
c. the β hemoglobin genes of mice and of humans
d. the fur that covers Australian moles and North American moles
e. the bones of bat forelimbs and the bones of bird forelimbs

7. Which of the following pairs are the best examples of homologous structures?
a. bones in the bat wing and bones in the human forelimb
b. owl wing and hornet wing
c. bat wing and bird wing
d. eyelessness in the Australian mole and eyelessness in the North American
mole

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8. When using a cladistic approach to systematics, which of the following is
considered most important for classification?
a. shared primitive characters
b. analogous primitive characters
c. shared derived characters
d. the number of homoplasies
e. overall phenotypic similarity

9. Use the figure below to answer the following question.

Which extinct species should be the best candidate to serve as the outgroup
for the clade whose common ancestor occurs at position 2 in Figure 26.1?
a. A
b. B
c. C
d. D
e. E

10. If Figure 26.1 is an accurate depiction of relatedness, then which of the

following should be correct?
1. The entire tree is based on maximum parsimony.
2. If all species depicted here make up a taxon, this taxon is monophyletic.
3. The last common ancestor of species B and C occurred more recently than
the last common ancestor of species D and E.
4. Species A is the direct ancestor of both species B and species C.
5. The species present at position 3 is ancestral to C, D, and E.
a. 1 and 3
b. 3 and 4
c. 2, 3, and 4
d. 1, 2, and 3

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 4. Content

Some Early Taxonomist

Taxonomy is the study of scientific classification, in particular the classification of

living organisms according to their natural relationships. Taxonomy's first father was the
philosopher Aristotle (384-322 BC), sometimes called the "father of science." It was
Aristotle who first introduced the two key concepts of taxonomy as we practice it today:
classification of oranisms by type and binomial
definition.

Aristotle was the first to attempt to classify

all the kinds of animals in his History of Animals
(Historia Animalium in Latin). He grouped the
types of creatures according to their similarities:
animals with blood and animals without blood,
animals that live on water and animals that live
on land. Aristotle's view of life was hierarchical.
He assumed that creatures could be grouped in
order from lowest to highest, with the human
species being the highest. Subsequent
commentators on Aristotle interpreted this as a
"ladder of nature" (scala naturae) or a "Great
Chain of Being," but these were not Aristotle's
terms. His system of classification was not
evolutionary, and the various species on the
ladder had no specific genetic relationship to each other. Aristotle regarded the essence
of species as fixed and unchanging, and this view persisted for the next two thousand
years.

His other innovation was binomial definition. "Binomial" means "two names," and
according to this system each kind of organism can be defined by the two names of its
"genus and difference." The word "genus" comes from the Greek root for "birth," and
among its meanings are "family" and "race." Aristotle's notion of definition was to place
every object in a family and then to differentiate it from the other members of that family
by some unique characteristic. He defined humans, for example, as the "rational animal."
This, according to Aristotelian thought, defines the essence of what it is to be human, as
opposed to such pseudo-definitions as "featherless biped."

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 But what Aristotle did not do was methodically use binomial definition in his system
of biological classification. This innovation had to await the development of modern
science after the Rennaissance.

Aristotle's influence was profound and long-lasting. Much of his work has not
survived to the present day, so that we don't know the details of his study of plants, but
his student Theophrastus(372-287 BC) continued it, becoming known as the "father of
botany." He is believed to have planted the first botanical garden on the grounds of
Aristotle's Lyceum. Most of the text of his two botanical works, On Plants (De Historia
Plantarum) and The Causes of Plants (De Causis Plantarum) still exists, although only in
Latin translations. The first describes the anatomy of plants and classifies them into trees,
shrubs, herbaceous perennials, and herbs. The second work discusses their propagation
and growth and served in part as a practical guide to farmers and gardeners. However,
he introduced no new principles of classification.

After Aristotle, there was little innovation in the fields of the biological sciences until
the 16th century AD. At this time, voyages of exploration were beginning to discover
plants and animals new to Europeans, which excited the interest of natural philosophers,
as scientists were then called. There was great interest in naming these new species and
fitting them into the existing classifications, and this in turn led to new systems of
classification. Many of the botanists of this period were also physicians, who were
interested in the use of plants for producing medicines.

Andrea Cesalpino (1519-1603) was an Italian

physician who created one of the first new systems
of classifying plants since the time of Aristotle. He
was a professor of materia medica, the study of
the preparation of medicines from plants, at the
University of Pisa, and was also in charge of the
university's botanical garden. There, he wrote a
series of works titled On Plants (De Plantis),
detailing his system of classification. While his work
was in large part based on the work of Aristotle
and his successors, his innovation in basing his
system of classifying plants on the basis of the
structure of their fruits and seeds influenced
subsequent scientists such as Linnaeus.

One botanist who was influenced by Cesalpino was Gaspard Bauhin (1560-1620), a
Swiss physician and anatomist. In his 1623 Illustrated Exposition of Plants (Pinax Theatri
Botanica), he described about six thousand species and gave them names based on their

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"natural affinities," grouping them into genus and species. He was thus the first scientist
to use binomial nomenclature in classification of species, anticipating the work of
Linnaeus.

By the time Carl (Carolus) Linnaeus (1707-

1778) was born, there were many systems of
botanical classification in use, with new plants
constantly being discovered and named. This, in
fact, was the problem — there were too many
inconsistent systems, and the same plant might
have several different scientific names, according to
different methods of classification.
During his childhood, Linnaeus was so fond of
collecting plants that he was known as "the little
botanist." He later became a physician, as so many
other early taxonomists did, but returned to botany
as his primary study.

He published his most innovative work as a

young man in 1735. The System of Nature
(Systema Naturae) is notable for an overall
framework of classification that organized all plants
and animals from the level of kingdoms all the way
down to species. The full subtitle of its tenth edition
was: System of nature through the three kingdoms
of nature, according to classes, orders, genera and
species, with characteristics, differences,
synonyms, places. This system of classification,
although greatly modified, is essentially the one we
use today.

Linnaeus followed this work with The Genera

of Plants and The Species of Plants, setting out a
system of plant classification based on the
structure of flower parts, in which he was
influenced by Cesalpino. This method, in which
plants were grouped together according to the
number of stamens in their flowers, for example, was not accurate, but it was easy to use
and thus readily adapted by scientists who were continually discovering more new
varieties of plants. Linnaeus himself undertook much work in the field, and he was even

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more influential through his students, whom he sent around the world to gather
specimens.

His major works went through a great deal of revision in his lifetime, eliminating
errors and coming closer to the system that was eventually adopted by taxonomists
worldwide. His methods of classifying plants have been completely superseded by a
deeper scientific understanding. Originally, Linnaeus had only used binomial nomenclature
to classify plants, but he later extended this system to include animals and even minerals.
There were also errors, subsequently corrected. At first, for example, he had placed the
whales among the fishes, but later moved them into the mammals. He was also the first
taxonomist to place humans among the primates (or Anthropomorpha) and to give them
the binomen Homo sapiens.

If Linnaeus is now considered the father of taxonomy, his success rested on the
work of his predecessors. He was the first, in his System of Nature, to combine a
hierarchical system of classification from kingdom to species with the method of binomial
nomenclature, using it consistently to identify every species of both plants and animals
then known to him.

While he continued throughout his lifetime to revise and expand this great work, so
his successors have continued to revise the principles of taxonomy, now according to
genetic principles, informed by the analysis of DNA. So it always is with science: we stand
on the shoulders of our predecessors, always reaching higher.

Linnaean Systems of Classification

The evolution of life on Earth over the past 4 billion years has resulted in a huge
variety of species. For more than 2,000 years, humans have been trying to classify the
great diversity of life. The science of classifying organisms is called taxonomy.
Classification is an important step in understanding the present diversity and past
evolutionary history of life on Earth.

All modern classification systems have their roots in the Linnaean classification system. It
was developed by Swedish botanist Carolus Linnaeus in the 1700s. He tried to classify all
living things that were known at his time. He grouped together organisms that shared
obvious physical traits, such as number of legs or shape of leaves. For his contribution,
Linnaeus is known as the “father of taxonomy.”

The Linnaean system of classification consists of a hierarchy of groupings, called

taxa (singular, taxon). Taxa range from the kingdom to the species (see Figure below).
The kingdom is the largest and most inclusive grouping. It consists of organisms that
share just a few basic similarities. Examples are the plant and animal kingdoms. The
species is the smallest and most exclusive grouping. It consists of organisms that are

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similar enough to produce fertile offspring together. Closely related species are grouped
together in a genus.

Linnaean Classification System:

Classification of the Human Species.
This chart shows the taxa of the
Linnaean classification system. Each
taxon is a subdivision of the taxon
below it in the chart. For example, a
species is a subdivision of a genus.
The classification of humans is given
in the chart as an example.

Binomial Nomenclature

Binomial nomenclature ("two-

term naming system") also called
binominal nomenclature ("two-name
naming system") or binary
nomenclature, is a formal system of naming species of living things by giving each a name
composed of two parts, both of which use Latin grammatical forms, although they can be
based on words from other languages. Such a name is called a binomial name (which may
be shortened to just "binomial"), a binomen, binominal name or a scientific name; more
informally it is also called a Latin name. The first part of the name identifies the genus to
which the species belongs; the second part – the specific name or specific epithet –
identifies the species within the genus. For example, humans belong to the genus Homo
and within this genus to the species Homo sapiens. Tyrannosaurus rex is probably the
most widely known binomial.[1] The formal introduction of this system of naming species
is credited to Carl Linnaeus, effectively beginning with his work Species Plantarum in 1753.
But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici
(English, Illustrated exposition of plants) many names of genera that were later adopted
by Linnaeus.

The application of binomial nomenclature is now governed by various

internationally agreed codes of rules, of which the two most important are the
International Code of Zoological Nomenclature (ICZN) for animals and the International
Code of Nomenclature for algae, fungi, and plants (ICN). Although the general principles
underlying binomial nomenclature are common to these two codes, there are some
differences, both in the terminology they use and in their precise rules.

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 In modern usage, the first letter of the first part of the name, the genus, is always
capitalized in writing, while that of the second part is not, even when derived from a
proper noun such as the name of a person or place. Similarly, both parts are italicized
when a binomial name occurs in normal text (or underlined in handwriting). Thus the
binomial name of the annual phlox (named after botanist Thomas Drummond) is now
written as Phlox drummondii.

In scientific works, the "authority" for a binomial name is usually given, at least
when it is first mentioned, and the date of publication may be specified.

Revisions in Linnaean Classification

Linnaeus published his classification system in the 1700s. Since then, many new
species have been discovered. The biochemistry of many organisms has also become
known. Eventually, scientists realized that Linnaeus’s system of classification needed
revision.

A major change to the Linnaean system was the addition of a new taxon called the
domain. Adomain is a taxon that is larger and more inclusive than the kingdom. Most
biologists agree there are three domains of life on Earth: Bacteria, Archaea, and Eukaryota
(see Figure below). Both Bacteria and Archaea consist of single-celled prokaryotes.
Eukaryota consists of all eukaryotes, from single-celled protists to humans. This domain
includes the Animalia (animals), Plantae (plants), Fungi (fungi), and Protista (protists)
kingdoms.

This phylogenetic tree is

based on comparisons of
ribosomal RNA base sequences
among living organisms. The tree
divides all organisms into three
domains: Bacteria, Archaea, and
Eukarya. Humans and other
animals belong to the Eukarya
domain. From this tree, organisms
that make up the domain Eukarya
appear to have shared a more
recent common ancestor with
Archaea than Bacteria.

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Classifying Organisms Based on Similar and Distinct Characters

Not surprisingly, biologists also classify organisms into different categories mostly
by judging degrees of apparent similarity and difference that they can see. The
assumption is that the greater the degree of physical similarity, the closer the biological
relationship.

Discovering an unknown organism, researchers begin their classification by looking

for anatomical features that appear to have the same function as those found on other
species. The next step is determining whether or not the similarities are due to an
independent evolutionary development or to descent from a common ancestor. If the
latter is the case, then the two species are probably closely related and should be classified
into the same or near biological categories.

Human arm bones (common bird, mammal, and reptile forelimb configuration)

Homologies are anatomical features, of different organisms, that have a similar

appearance or function because they were inherited from a common ancestor that also
had them. For instance, the forelimb of a bear, the wing of a bird, and your arm have
the same functional types of bones as did our shared reptilian ancestor. Therefore, these
bones are homologous structures. The more homologies two organisms possess, the
more likely it is that they have a close genetic relationship.

There can also be nonhomologous structural similarities between species. In these

cases, the common ancestor did not have the same anatomical structures as its
descendants. Instead, the similarities are due to independent development in the now
separate evolutionary lines. Such misleading similarities are called homoplasies.
Homoplastic structures can be the result of parallelism, convergence, or mere chance.

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 Parallelism or parallel evolution, is a similar evolutionary development in different
species lines after divergence from a common ancestor that did not have the characteristic
but did have an initial anatomical feature that led to it. For instance, some South American
and African monkeys evolved relatively large body sizes independently of each other.
Their common ancestor was a much smaller monkey but was otherwise reminiscent of
the later descendant species. Apparently, nature selected for larger monkey bodies on
both continents during the last 30 million years.

Convergence or convergent evolution, is the development of a similar anatomical

feature in distinct species lines after divergence from a common ancestor that did not
have the initial trait that led to it. The common ancestor is usually more distant in time
than is the case with parallelism. The similar appearance and predatory behavior of North
American wolves and Tasmanian wolves (thylacines) is an example. The former is a
placental mammal like humans and the latter is an Australian marsupial like kangaroos.
Their common ancestor lived during the age of the dinosaurs 125 million years ago and
was very different from these descendants today. There are, in fact, a number of other
Australian marsupials that are striking examples of convergent evolution with placental
mammals elsewhere.

Australian Tasmanian wolf or tiger (now extinct) North American wolf

Both parallelism and convergence are thought to be due primarily to separate

species lines experiencing the same kinds of natural selection pressures over long periods
of time.

Analogies are anatomical features that have the same form or function in different
species that have no known common ancestor. For instance, the wings of a bird and a
butterfly are analogous structures because they are superficially similar in shape and
function. Both of these very distinct species lines solved the problem of getting off of the
ground in essentially the same way. However, their wings are quite different on the inside.
Bird wings have an internal framework consisting of bones, while butterfly wings do not
have any bones at all and are kept rigid mostly through fluid pressure. Analogies may be
due to homologies or homoplasies, but the common ancestor, if any, is unknown.

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Problems in Classifying Organisms

Listing characteristics that distinguish one species from another has the effect of
making it appear that the species and their distinctive attributes are fixed and eternal.
We must always keep in mind that they were brought about by evolutionary processes
that operated not merely at some time in the distant past, but which continue to operate
in the present and can be expected to give rise to new forms in the future. Species are
always changing. As a consequence, they are essentially only a somewhat arbitrarily
defined point along an evolutionary line.

It is also important to realize that most species are physically and genetically diverse.
Many are far more varied than humans. When you think of an animal, such as the jaguar
shown on the right, and describe it in terms of its specific traits (fur color patterns, body
shape, etc.), it is natural to generalize and to think of all jaguars that way. To do so,
however, is to ignore the reality of diversity in nature.

Another problem in classifying a newly discovered organism is in determining the

specific characteristics that actually distinguish it from all other types of organisms. There
is always a lively debate among researchers over defining new species because it is not
obvious what are the most important traits. There are two schools of thought in resolving
this dilemma. The first defines new species based on minor differences between
organisms. This is the splitter approach. The second tends to ignore minor differences
and to emphasize major similarities. This lumper approach results in fewer species being
defined. Ideally, this dispute could be settled by breeding experiments--if two organisms
can mate and produce fertile offspring, they are probably members of the same species.
However, we must be careful because members of very closely related species can
sometimes produce offspring together, and a small fraction of those may be fertile. This
is the case with mules, which are the product of mating between female horses and male
donkeys. About one out of 10,000 mules is fertile. Does this mean that horses and

12
donkeys are in the same species? Whatever the answer may be, it is clear that species
are not absolutely distinct entities, though by naming them, we implicitly convey the idea
that they are.

Breeding experiments are rarely undertaken to determine species boundaries

because of the practical difficulties. It is time consuming and wild animals do not always
cooperate. Using this kind of reproductive data for defining species from the fossil record
is impossible since we cannot go back in time to observe interspecies breeding patterns
and results. Likewise, we cannot carry out a breeding experiment between ourselves and
our ancestors from a million years ago. Comparisons of DNA sequences are now becoming
more commonly used as an aid in distinguishing species. If two animals share a great
many DNA sequences, it is likely that they are at least closely related. Unfortunately, this
usually does not conclusively tell us that they are members of the same species.
Therefore, we are still left with morphological characteristics as the most commonly used
criteria for identifying species differences.

The Linnaean scheme for classification of living things lumps organisms together
based on presumed homologies. The assumption is that the more homologies two
organisms share, the closer they must be in terms of evolutionary distance. Higher, more
inclusive divisions of the Linnaean system (e.g., phylum and class) are created by including
together closely related clusters of the immediately lower divisions. The result is a
hierarchical system of classification with the highest category consisting of all living things.
The lowest category consists of a single species. Each of the categories above species
can have numerous subcategories. In the example below, only two genera (plural of
genus) are listed per family but there could be many more or only one.

Most researchers today take a cladistics approach to classification. This involves

making a distinction between derived and primitive traits when evaluating the importance
of homologies in determining placement of organisms within the Linnaean classification
system. Derived traits are those that have changed from the ancestral form and/or
function. An example is the foot of a modern horse. Its distant early mammal ancestor
had five digits. Most of the bones of these digits have been fused together in horses
giving them essentially only one toe with a hoof. In contrast, primates have retained the
primitive characteristic of having five digits on the ends of their hands and feet. Animals
sharing a great many homologies that were recently derived, rather than only ancestral,
are more likely to have a recent common ancestor. This assumption is the basis of
cladistics.

The Dichotomous Key

Classification is important in understanding the natural world. It is a specific way of

organizing information so that it can be more useful. Recent estimates suggest there are
nearly 9 million living things on Earth today, and that’s not even including bacteria and

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archaea. Classification of these living things helps us see similarities and differences that
exist among these diverse organisms. Scientists have classified many millions of living
species based on their physical characteristics and they have given a unique name to each
unique species. The scientists who classify living things record their classifications so that
later, others who encounter a certain species will be able to identify it in the same way.
Making sure that two scientists are referring to the same thing when using a certain name
is important for clear communication. Dichotomous keys help guide scientists toward
identification, so classifications can be shared and used mutually. A dichotomous key is a
guide for classification and identification, somewhat like a map through a classification
system that was developed previously. Dichotomous comes from the Greek root dich-,
meaning "two" and -tomy, meaning, "to cut." By asking a series of questions to which
there are only two possible answers with respect to the object to be identified, the key
leads users toward the proper identification. Many parts of the natural world that have
been classified, categorized, and grouped can be identified using a dichotomous key.
Dichotomous keys can be developed to identify anything in any sort of classification.

5. Related/Suggested/Activities

Constructing a Cladogram:

1. Use the data below to arrange the groups of organisms based on their shared
derived traits. This time you will be using distantly related organisms or a taxon
termed an outgroup.
2. For each group, the traits or characters are already listed. For each character,
determine which state is ancestral or primitive and which is derived. This is usually
done by comparing with the outgroup. Traits found in the outgroup are likely to
be ancestral or primitive. Similarly, traits not found in the outgroup are considered
as derived. In cladistics, it is the derived trait shared among taxa that should be
placed in the cladogram.
3. Group taxa according to their shared derived character(s).
4. Once you have evaluated all the characters, you may start constructing your
cladogram. Where do you place the outgroup? (An outgroup is always placed at
the base of the cladogram)

Expected Cladogram:

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5. Post Assessment
Direction: Choose the letter that corresponds to the word or phrase that best
completes the sentence.

1. In a comparison of birds and mammals, the condition of having four limbs is

a. a shared ancestral character.
b. a shared derived character.
c. a character useful for distinguishing birds from mammals.
d. an example of analogy rather than homology.

2. Based on the tree below, which statement is not correct?

a. The salamander lineage is a basal taxon.

b. Salamanders are a sister group to the group containing lizards, goats, and
humans.
c. Salamanders are closely related to goats as to humans.
d. Lizards are more closely related to salamanders than to humans.

15
3. The various taxonomic levels (namely, genera, classes, etc.) of the hierarchical
classification system differ from each other on the basis of
a. how widely the organisms assigned to each are distributed throughout the
environment.
b. their inclusiveness.
c. the relative genome sizes of the organisms assigned to each.
d. morphological characters that are applicable to all organisms.

4. If organisms A, B, and C belong to the same class but to different orders and if
organisms D, E, and F belong to the same order but to different families, which of
the following pairs of organisms would be expected to show the greatest degree
of structural homology?
a. A and B
b. A and C
c. B and D
d. D and F
5. Linnaeus was a "fixist" who believed that species remained fixed in the form in
which they had been created. Linnaeus would have been uncomfortable with
a. classifying organisms using the morphospecies concept.
b. the scientific discipline known as taxonomy.
c. phylogenies.
d. nested, ever-more inclusive categories of organisms.
e. a hierarchical classification scheme.

6. The term homoplasy is most applicable to which of the following features?

a. the legless condition found in various lineages of extant lizards
b. the five-digit condition of human hands and bat wings
c. the β hemoglobin genes of mice and of humans
d. the fur that covers Australian moles and North American moles
e. the bones of bat forelimbs and the bones of bird forelimbs

7. Which of the following pairs are the best examples of homologous structures?
a. bones in the bat wing and bones in the human forelimb
b. owl wing and hornet wing
c. bat wing and bird wing
d. eyelessness in the Australian mole and eyelessness in the North American
mole

8. When using a cladistic approach to systematics, which of the following is

considered most important for classification?
a. shared primitive characters

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 b. analogous primitive characters
c. shared derived characters
d. the number of homoplasies
e. overall phenotypic similarity

9. Use the figure below to answer the following question.

Which extinct species should be the best candidate to serve as the outgroup
for the clade whose common ancestor occurs at position 2 in Figure 26.1?
a. A
b. B
c. C
d. D
e. E

10. If Figure 26.1 is an accurate depiction of relatedness, then which of the

following should be correct?

1. The entire tree is based on maximum parsimony.

2. If all species depicted here make up a taxon, this taxon is monophyletic.
3. The last common ancestor of species B and C occurred more recently than
the last common ancestor of species D and E.
4. Species A is the direct ancestor of both species B and species C.
5. The species present at position 3 is ancestral to C, D, and E.
a. 1 and 3
b. 3 and 4
c. 2, 3, and 4
d. 1, 2, and 3

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6. References:

https://davesgarden.com/guides/articles/printstory.php?rid=2051&bn=%2Farticles%2Fview%2F20
51
https://bio.libretexts.org/TextMaps/Introductory_and_General_Biology/Book%3A_Introductory_Biol
ogy_(CK-12)/5%3A_Evolution/5._10%3A_Linnaean_Classification
https://www2.palomar.edu/anthro/animal/animal_2.htm
https://dloft.stanford.edu/sites/default/files/designing_a_classification_tool_lesson_1.pdf
https://en.wikipedia.org/wiki/Binomial_nomenclature

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