We often take for granted the elegant simplicity that a species
name might take. However, a name often provides the
tag from which we can hang the evolutionary relationships and classification of
an organism… so, it is worth explaining how and why we name beasties. To start
somewhere we are all familiar with, a popular name. Palaeontologists have the rather fun habit of giving dinosaurs a nickname when excavating a skeleton…especially when the said remains are either rare, complete or both. The T. rex skeletons of Sue and Stan were named after their
respective finders. The name for the mummified hadrosaur dinosaur that Tyler
Lyson and I excavated a few years back, was based on the simple fact of its
geographical provenance ('Dakota'). However, all types of birds, mammals (including
ourselves), fish, amphibians, reptiles, crustaceans to bacteria have at least
two 'official' names that follow internationally accepted codes for naming plants and
animals. These are the International Code for Zoological Nomenclature (ICZN)
and the International Code for Botanical Nomenclature (ICBN). Within these two books
are the rules of naming a new species. A new name is given only when the plant or
animal that has been discovered is shown to be distinct from any
known species. The animal, its morphology, fossil and/or structure is then
formally described and published within a peer-reviewed journal (that is
usually the fun part!). A new species is then ‘born’ unto the blinding light of
the scientific world, and often makes a brief appearance in the wider world,
via the media….usually hailed at the end of the news programme by the words ‘And finally’…'And
finally scientists at the University of Dunking Buckets have discovered the
fossil remains of a new species of predatory dinosaur with feathers, etc. etc.’
Having feathers and being a predatory dinosaur usually ensures such stardom.
The classification of specific plants and animals into
distinct groups or tribes is also worth a quick review. Carl Linnaeus (his name was really von Linne, but he even translated his own name into latin!) devised
the binomial ('two-name') system applied to naming plants and animals in his splendid work Systema
Naturae, published in 1735. Linnaeus subdivided a name into first the genus and
then species names, for example you are Homo sapian (written always in
italics). The Linnaean system allowed species to be classified within a
hierarchical structure, starting with kingdoms. Kingdoms were divided into
Classes, then Orders, which were further divided into Genera, eventually
divided into Species. The classification was based upon observable characters,
meaning that many early classifications resulted in very strange family trees.
The more specimens and morphological characters you have, usually the more
robust the family tree...but this does not stop single bones representing a whole species. However, a new fossil or living beastie that possesses a very distinct
character, say a theropod dinosaur with feathers and a peg-leg, can have an impact that is far from proportional to its evolutionary
‘importance’ in the fossil record of all life (such is the draw of toothy
beasties with pirate tendencies).
Our own evolutionary path parted with the ancestors of
dinosaurs some time in Carboniferous Period, when the diapsids (reptiles and
later to include birds) and synapsids (to become mammals) parted evolutionary
company. However, the basic tetrapod (‘four-feet’) skeletal plan is still
recognizable, shared between vertebrates…even palaeontologists! I love
taking my undergraduate class to The Manchester Museum across the road from my
University Department in which I teach. Getting students to recognise the five
fingers in the hand (pectoral fin) of a sperm whale (Physeter mcrocephalus), the vestigial
hips (ilia) and seven neck (cervical) vertebrae and to compare with elephants (Loxodonta sp.),
antelopes (Antilope sp.) and chimpanzees (Pan troglodytes), the conservative
skeletal blueprint is such a splendid example of such shared relationships. The evolutionary
distance between one animal to another is beautifully displayed by their morphological
'distance', a function of the selective pressures that have often dictated the
survival of a species. There is no vim divinam at work, purely the elegant
simplicity of ‘decent with modification'...as so eloquently put by Charles Darwin.
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