The classification of Fossils – What’s in a Name (please no more T. Rex)

By | February 13th, 2008|Main Page, Palaeontological articles|0 Comments

The Classification and Naming of Fossils – Tyrannosaurus rex

Animals, fungi and plants are arranged by scientists into various groupings to assist with the classification of the vast amount of life on this planet.  Extinct organisms are treated in the same way as extant organisms (those which are around today).  All life on Earth belongs to one of three Kingdoms  Animalia, Plantae and another Kingdom for the Fungi, this is the largest grouping of organisms.  Scientists then further sub-divide organisms into other categories, organising creatures, plants and fungi in such a way that common features lead to organisms being associated together until an individual species is defined.  This is the accepted method of classifying life (although cladistics has added a new dimension or two), the principles of this form of classification were laid down by the Swedish botanist Carolus Linnaeus in the 18th Century.

The categories of classification from Kingdom down to the species level is referred to as a taxonomic hierarchy.  Organisms should be classified to reflect evolutionary relationships, with each taxon representing organisms that share a common ancestor, very similar to the “Tree of Life” analogy.

A Table Showing the Taxonomy of Tyrannosaurus rex

Taxonomic Hierarchy of Tyrannosaurus rex
Category Taxon Contents of Taxon
Kingdom Animalia All animals
Phylum Chordata All vertebrates (plus some minor groups)
Class Reptilia All reptiles
Order Saurischia All lizard-hipped dinosaurs
Sub-Order Theropoda The “beast footed” dinosaurs mainly carnivores
Family Tyrannosauroidea All Tyrannosaurs and close relatives of Tyrannosaurs
Genus Tyrannosaurus The closest relatives of all to Tyrannosaurus rex
Species Tyrannosaurus rex The individual species known as T. rex

Source: Everything Dinosaur

To be absolutely correct the name of all taxa (the plural for taxon) should begin with a capital letter, except for the individual species name which should always begin with a lower-case letter.  The scientific name for a particular organism consists of two Latin or Latinised words that are always the genus followed by the species classification.  This is termed the binomial.  It ensures that scientists from all over the world can communicate effectively between them when it comes to describing the characteristics of an individual organism.  The genus, such as Tyrannosaurus can be used on its own but the species name i.e. rex without the genus associated with it has no meaning, as some species names apply to more than one genus.  Formerly they should be typed in italics such as Tyrannosaurus rex and indeed this is the method chosen by members of Everything Dinosaur if they were to publish formal papers.  If it is not possible to put the genus and the species in italics (such as in a handwritten report), it is the convention to underline, for example Tyrannosaurus rex.

In this way, all scientists, including palaeontologists have a classification framework to use.  However, there are one or two more conventions to consider when classifying and naming animals such as dinosaurs, (or indeed all organisms for that matter).  If a dispute arises as to the naming of an organism then it is convention for the earliest name, the first description, to take precedence.  In this way, the name Brontosaurus was replaced by Apatosaurus.  There have been some notable exceptions to this and T. rex is one of them.

In the late 19th Century a good few years before T. rex was named and described by Osborn (1905), the notable American palaeontologist, Edward Drinker Cope described two badly eroded vertebrae as Manospondylus gigas.  This strange honey-combed back bone was different to any other dinosaur fossils found and it was given this name.  One of these bones has since been lost, however, the name stood and if scientific nomenclature was followed, as this bone is believed to represent a Tyrannosaurus rex then T. rex, the “Tyrant Lizard King” should be renamed Manospondylus gigas “Giant Thin Vertebrae” – not quite such an exciting name, I think you will agree.

The debate as to the true name of Tyrannosaurus rex was brought to wider public attention when in 2000 a team from the renowned Black Hills Institute of Geological Research (Pete Larson et al), claimed they had found the original site where Cope had unearthed the weathered fossil bones described as Manospondylus.  Fossils found on this site, presumably from the same specimen that Cope studied almost a Century before turned out to be T. rex so Tyrannosaurus rex should have been renamed based on this evidence.  The International Code of Zoological Nomenclature (ICZN) states that if further remains are found and these are identical to the those of the earlier discovery then the earlier name and description should be used.

This led to much consternation amongst scientists (and amongst Hollywood directors, as Manospondylus sounded nowhere near as cool as Tyrannosaurus rex).  However, in 2000 the ICZN ruled (fourth edition); that T. rex should stay, as the name had been cited in numerous works by many authors and the case of mistaken identity was more than fifty years old.

So it looks like T. rex is going to be able to stay as T. rex.  Now all we have to do is to convince the many authors, designers, artists and manufacturers we work with to use the appropriate scientific guide for stating this animal’s name, stating the species in lower case.  I know we can occasionally have a lapse but really there is no excuse when designing hang tags or packaging of models and other toys.  However, despite our best efforts we will still see Tyrannosaurus Rex printed and written down, when the it is only the genus part of the binomial that should be given a capital letter.