''Heleosuchus'' 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 ...

of diapsid reptile 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, ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

. It was originally described as a species of ''Saurosternon'' by

Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Owe ...

. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''Saurosternon griesbachi''. The specific name honours Carl Ludolf Griesbach. It was later recognized as a separate genus by

Robert Broom Robert Broom FRS FRSE (30 November 1866 6 April 1951) was a British- South African doctor and palaeontologist. He qualified as a medical practitioner in 1895 and received his DSc in 1905 from the University of Glasgow. From 1903 to 1910, he ...

. At one time, the

type specimen In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...

of ''Heleosuchus'' was thought to be lost. However, it remains at the

Natural History Museum, Vienna The Natural History Museum Vienna (german: Naturhistorisches Museum Wien) is a large natural history museum located in Vienna, Austria. It is one of the most important natural history museums worldwide. The NHM Vienna is one of the largest museum ...

, where it is numbered NHMW 2374, while the

Natural History Museum A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more. ...

(formerly British Museum (Natural History)) possesses a cast numbered R. 5000. Several other casts of NHMW 2374 are present in several other European institutions, among them a cast of higher fidelity to the original. While the type was thought to be lost,

Susan E. Evans Susan E. Evans is British palaeontologist and herpetologist. She is the author or co-author of over 100 peer-reviewed papers and book chapters. She received a BSc in Zoology at Bedford College in 1974, and in 1977 a PhD in vertebrate palaeon ...

redescribed this taxon on the basis of an older mold which had been taken of the type specimen prior to its disappearance. When the specimen appeared in later years, a higher quality mold was taken and described by

Robert L. Carroll Robert "Bob" Lynn Carroll (May 5, 1938 – April 8, 2020) was an American–Canadian vertebrate paleontologist who specialised in Paleozoic and Mesozoic amphibians and reptiles. Biography Carroll was an only child and grew up on a farm ne ...

that allowed a better description of this taxon. ''Heleosuchus'' is only known from the posterior half of the skull and a cervicodorsal column with some associated forearm elements and hindlimb elements. The hindlimbs are better preserved than the forearms. ''Heleosuchus'' is suggested as being either an early diapsid reptile, not closely related to other lineages, or as being an aberrant and primitive lepidosauromorph. ''Heleosuchus'' shares the hooked fifth metatarsal found in some other diapsids, such as primitive turtles (''

Odontochelys ''Odontochelys semitestacea'' (meaning "toothed turtle with a half-shell") is a Late Triassic relative of turtles. Before ''Pappochelys'' was discovered and ''Eunotosaurus'' was redescribed, ''Odontochelys'' was considered the oldest undisputed m ...

''), lepidosauromorphs, and archosauromorphs, but it also resembles "younginiform"-grade diapsids in its gross morphology. ''Heleosuchus'' may also share a thyroid fenestra with these higher diapsid reptiles as well, but the identity of this feature is disputed.

References

{{Taxonbar, from=Q5704237 Permian reptiles of Africa Prehistoric neodiapsids Prehistoric reptile genera

See also

References