''Gordonia'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivores that typically bore a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, t ...

therapsid from the

Late Permian Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudonym used by Dave Groh ...

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

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

Elgin, Moray Elgin ( ; ; ) is a historic 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 ground above th ...

. 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 the ...

. ''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. * ...

''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 excepti ...

. A long intertemporal region is usually associated with larger dicynodonts, making the skull proportions of ''Gordonia'' unusual. The endocast of ''Gordonia'' displays an enlarged pineal body, a feature likely linked to the enlargement of the sagittal crest.

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 ("near-reptiles") is an extinct group of Basal (phylogenetics), basal Sauropsida, sauropsids ("Reptile, reptiles"), traditionally considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds ...

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, Moray, Elgin in Scotland, which has yielded many fossils referred to as the Elgin Reptiles. Discovery ...

''. 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 who specialized 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 (; July 13, 1860 – December 28, 1917) (alternative spelling: Amalitzky) was a paleontologist and professor at Warsaw University. He was involved in the discovery and excavation of the Late Permian fossil vertebra ...

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''. 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 () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

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

Gordonia traquairi restoration and skull

Below is a

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

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

References

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