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Taxonomy Rules Naming And Grouping Animals Scientifically
Explaining the rules for scientific naming and classiciation of animals
Date : 11/03/2016
Author Information
Uploaded by : Sebastian
Uploaded on : 11/03/2016
Subject : Biology
The taxonomic system for the hierarchical (ranked) classification of living organisms (and initially also of rocks, but that failed) is very simple. Organisms are assigned into different groups based on their characteristics, and these groups are hierarchical. The figure below shows the seven main types of groups. Kingdom is higher than phylum, while class is lower , and so on.
For some, but not all groups there are subdivisions of these
group types, such as subclass (subdivision within a class), infraorder
(subdivision within a suborder i.e. infra- is below sub-), and
grouping of groups e.g. superorder (group of orders).
Since the system is hierarchical, organisms belonging to the same class
also belong to the same phylum and kingdom. For instance, all animals
belonging to the class Reptilia (reptiles, then) also belong to the
phylum Chordata (animals with a notochord, or backbone) and the kingdom
Animalia (animals).
Now, the order Primates (primates), although belonging to the class
Mammalia instead of Reptilia, also belongs to the phylum Chordata and
kingdom Animalia. This might complicate things, but it is simply due to
that the two classes Reptilia and Mammalia both belong to the same
phylum and (therefore) kingdom. Notice that the name of the class is
written with a capital first letter when you refer to the actual group.
If you instead write carnivorans (belonging to the mammalian order
Carnivora not equal to carnivore , which refers to a feeding strategy
not a taxonomic group), you are really referring to the members of the
group, and you do not use capital letters. This rule is useful for
distinguishing between, for example, Primates and primates.
While on the subject of formal rules, the genus and species are
special. First, both are always written in italics. Always. Second, the
genus name is written with capital first letter, but the species never
has a capital. Third, you may refer to the genus alone, e.g. Tyrannosaurus,
but never ever write only the species name. Never. This is because
there may be several different species with the same name, (for
instance, they may be named after the same discoverer) but they never
belong to the same genus (if they do, they are simply not allowed to
have the same species name). In this way, we get an endless variety of
specific names for an endless variety of species. Finally, you may
shorten the genus name to only the first letter (capital) followed by a
dot and the species name (if you do not include the species name, you
may not shorten the genus name it would be silly to write something
like T. had remarkably short arms ). For example, we take the genus Tyrannosaurus (species name is excluded, since I refer to the genus), which has one species: Tyrannosaurus rex although some researchers argue that Tarbosaurus bataar really belongs to Tyrannosaurus in that case, we would also have Tyrannosaurus bataar
(the species name is the same, but is assigned to a different genus).
Notice that I should not shorten the genus name here, since it may be
unclear what I mean by T. bataar.
Names can be discarded or invalidated, usually by
showing that two very similar species actually are the same, in which
case the name given first is the one that remains valid. Rejected names
are written within quotation marks, and never italicised. A classical
example is that "Brontosaurus exelsus" and Apatosaurus ajax were shown to be the same species (and therefore also belonged to one and the same genus) Apatosaurus, being the first to have been described and named, was kept (both genus and species name).
Another notable convention is that families tend to end with -idae,
superfamilies with -oidea and subfamilies with -inae (their members
would then be -ids, -oids, and -ines, respectively). For example, we
have the Hadrosauroidea (superfamily), Hadrosauridae (family) and
Hadrosaurinae (subfamily).
Nowadays, the taxonomic system has been overshadowed by phylogenetic
systematics, or cladistics. Cladistics is favoured because it
systematically investigates evolutionary relationships, rather than just
putting the organisms into different groups cladistics tries to work
out how they evolved, and how closely related different organisms are.
Taxonomy, on the other hand, merely groups similar-looking organisms
together in order to make some sense of the overwhelming chaos of life
we have out there.
The groupings can differ quite a lot between taxonomy and
cladistics, since cladistics has a predilection for groups that include
all the descendants within an evolutionary line (i.e. monophyletic
clades). Therefore, cladistics disregards the group Reptilia, as it does
not include birds (class Aves) and mammals, both which have their
origins in the reptilian evolutionary line. Instead, cladistics just
group them all together as Amniota.
This resource was uploaded by: Sebastian