''Gordonia'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typica ...

therapsid Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented mor ...

from the

Late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to th ...

. Fossils have been found from the Elgin sandstone of Cutties Hillock Quarry in

Elgin, Moray Elgin (; sco, Ailgin; gd, Eilginn, ) is a town (former cathedral city) and formerly a Royal Burgh in Moray, Scotland. It is the administrative and commercial centre for Moray. The town originated to the south of the River Lossie on the higher ...

. These are among the many amniote fossils referred to as the Elgin Reptiles. ''Gordonia'' was named in 1893 with four species: ''G. traquairi'', ''G. duffiana'', ''G. huxleyana'', and ''G. juddiana''. Currently, the only recognized species is the

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...

''G. traquairi''. All other species are considered synonyms of the type.

Description

''Gordonia'' is known from several skulls and partial skeletons. It is small-bodied in comparison to other dicynodonts. It is distinguished by the rod-like shape of a ridge on its lower jaw called the lateral dentary shelf. ''Gordonia'' has a short snout with tusks that are angled slightly forward. The intertemporal region at the top of the skull is long and narrow and forms a raised

sagittal crest A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exceptiona ...

. A long intertemporal region is usually associated with larger dicynodonts, making the skull proportions of ''Gordonia'' unusual.

History

Fossils of ''Gordonia'' were first found by Scottish naturalist Ramsay Heatley Traquair in 1885, who immediately identified them as belonging to a dicynodont. They included several partial skeletons and complete skulls. All of these remains were preserved as impressions in sandstone, and no fossilized bones were found. On the basis of these impressions, E. T. Newton named ''Gordonia'' in 1893. ''Gordonia'' was named alongside a similar dicynodont, '' Geikia'', and the small

parareptile Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids (reptiles), typically considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near the ...

'' Elginia''. Newton named four species of ''Gordonia'', including ''G. traquairi'' (named after Traquair), ''G. duffiana'', ''G. huxleyana'' (named after

Thomas Henry Huxley Thomas Henry Huxley (4 May 1825 – 29 June 1895) was an English biologist and anthropologist specialising in comparative anatomy. He has become known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution. The stor ...

), and ''G. juddiana''. In 1922, Russian paleontologist

Vladimir Prokhorovich Amalitskii Vladimir Prokhorovich Amalitskii (russian: Владимир Прохорович Амалицкий; 1860–1917) (alternative spelling: Amalitzky) was a Russian paleontologist and professor at Warsaw University who was involved in the discovery a ...

named two more species of ''Gordonia'', ''G. annae'' and ''G. rossica''. In 1926, ''G. annae'' and ''G. rossica'' were distinguished from the other species of ''Gordonia'' and transferred to the genus '' Dicynodon''. Both species are now considered synonyms of ''

Vivaxosaurus trautscholdi ''Vivaxosaurus'' is a genus of dicynodont from Late Permian (Changhsingian) of Russia. It has been found at Sokolki on the Northern Dvina River near Kotlas in Arkhangelsk Oblast, Russia. It lived during the latest Permian, and was a contempor ...

''. In 1988, British paleontologist Gillian King synonymized all species of ''Gordonia'' with ''Dicynodon'', creating the single species ''Dicynodon traquairi''. This classification was widely accepted in the following years. In 2011, a

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis of ''Dicynodon'' species found ''D. traquairi'' to be only distantly related to other species. The name ''Gordonia'' was reinstated, although only one species, ''G. traquairi'', was recognized.

Classification

Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

showing the phylogenetic placement of ''Gordonia'' from Kammerer ''et al.'' (2011):

References

{{Taxonbar, from=Q5586050 Fossils of Scotland Dicynodonts Lopingian synapsids of Europe Fossil taxa described in 1893 Elgin, Moray History of Moray Anomodont genera