''Picrodon'' is the name given to a genus of

archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avian d ...

, possibly a

sauropodomorph Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had lon ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

, from the

Rhaetian The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest age ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

which was possibly synonymous with the dubious archosaur ''

Avalonianus ''Avalonianus'' is a highly dubious and possibly invalid genus of archosaur from the Late Triassic of England. It was first described in 1898 by Harry Seeley with the name ''Avalonia'',H. G. Seeley. 1898. On large terrestrial saurians from the Rh ...

''. The type, and only species, ''P. herveyi'', was named in 1898.H. G. Seeley. 1898. On large terrestrial saurians from the Rhaetic Beds of Wedmore Hill, described as '' Avalonia sanfordi'' and ''Picrodon herveyi''. Geological Magazine, decade 4 5:1-6

Discovery and naming

In 1894, W. A. Sanford described the fossil remains of what he considered to be two large

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

s discovered near

Westbury-on-Severn Westbury-on-Severn is a rural village in England that is the centre of the large, rural parish, also called Westbury-on-Severn. Location The village is situated on the A48 road (between Minsterworth and Newnham on Severn) and bounded by the R ...

Glastonbury Glastonbury (, ) is a town and civil parish in Somerset, England, situated at a dry point on the low-lying Somerset Levels, south of Bristol. The town, which is in the Mendip district, had a population of 8,932 in the 2011 census. Glastonbury ...

(

Westbury Formation The Westbury Formation is a geological formation in England, one of the Penarth Group. It dates back to the Rhaetian.Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Triassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and ...

) by Eev. Sydenham H. A. Hervey and Sanford himself.''Proceedings of the Somerset Archaeological Society'' - vol. xl, 1894, p. 234

Harry Govier Seeley Harry Govier Seeley (18 February 1839 – 8 January 1909) was a British paleontologist. Early life Seeley was born in London on 18 February 1839, the second son of Richard Hovill Seeley, a goldsmith, and his second wife Mary Govier. When his fat ...

described the fossils and named two genera: ''

Avalonia Avalonia was a microcontinent in the Paleozoic era. Crustal fragments of this former microcontinent underlie south-west Great Britain, southern Ireland, and the eastern coast of North America. It is the source of many of the older rocks of Wester ...

'' (preoccupied; now ''

'') and ''Picrodon''; both are based solely on teeth. Only a single

tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

, holotype BMNH R2875, belonging to ''P. herveyi'' is known, making the remains not sufficient enough to make judgments on its diet or its classification; although it is agreed that ''Picrodon'' was an archosaur to some degree.

Classification

Sanford (1894) classified ''Picrodon'' as a

, while Seeley (1898) classified ''Picrodon'' as a

saurian Sauria is the clade containing the most recent common ancestor of archosaurs (such as crocodilians, dinosaurs, etc.) and lepidosaurs ( lizards and kin), and all its descendants. Since most molecular phylogenies recover turtles as more closel ...

. More modern research however almost certainly places ''Picrodon'' within Archosauria;

Peter Malcolm Galton Peter Malcolm Galton (born 14 March 1942 in London) is a British vertebrate paleontologist who has to date written or co-written about 190 papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosa ...

(1985) suggested that ''Picrodon'' may have been a basal sauropodomorph. Currently, its exact phylogenetic placement within Archosauria remains unknown.

References

Archosaurs Triassic archosaurs Fossil taxa described in 1898 {{paleo-archosaur-stub es:Picrodon fr:Picrodon it:Picrodon solus