''Gordonia'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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, typicall ...

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 more ...

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 the ...

. 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 gr ...

. These are among the many amniote fossils referred to as the

Elgin Reptiles Elgin Reptiles is the name given to the Permian and Triassic fossils found in the sandstone deposits in and around the town of Elgin, in Moray, Scotland. They are of historical and scientific importance, and many of the specimens are housed in th ...

. ''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 ''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 Ramsay Heatley Traquair FRSE FRS (30 July 1840 – 22 November 1912) was a Scottish naturalist and palaeontologist who became a leading expert on fossil fish. Traquair trained as a medical doctor, but his thesis was on aspects of fish anatom ...

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 ''Geikia'' is an extinct genus of dicynodont therapsids from the late Permian. The abundance and diversity of dicynodonts during this period, combined with incomplete or inadequately prepared specimens, have led to challenges in determining relat ...

'', 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 ''Elginia'' is an extinct genus of pareiasaurid known from the Late Permian of Scotland and China. It was named for the area around Elgin in Scotland, which has yielded many fossils referred to as the Elgin Reptiles. Discovery The type s ...

''. 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 storie ...

), and ''G. juddiana''. In 1922, Russian paleontologist Vladimir Prokhorovich Amalitskii 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 ''Dicynodon'' ("two dog-teeth") is a genus of dicynodont therapsid that flourished during the Upper Permian period. Like all dicynodonts, it was herbivorous animal. This reptile was toothless, except for prominent tusks, hence the name. It probab ...

''. 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 contempora ...

''. In 1988, British paleontologist

Gillian King Gillian may refer to: Places * Gillian Settlement, Arkansas, an unincorporated community People Gillian (variant Jillian) is an English feminine given name, frequently shortened to Gill. It originates as a feminine form of the name Julian, Julio ...

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 d ...

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