''Neosaurus'' is an extinct genus of

pelycosaur Pelycosaur ( ) is an older term for basal or primitive Late Paleozoic synapsids, excluding the therapsids and their descendants. Previously, the term ''mammal-like reptile'' had been used, and pelycosaur was considered an order, but this is ...

-grade

synapsid Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...

s from the

Late Carboniferous 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, ...

- Early Permian of the Jura region of

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

. It is known only from a partial

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...

or upper jaw bone and an associated impression of the bone. The teardrop shape of the teeth in the jaw indicate that ''Neosaurus'' belongs to the family

Sphenacodontidae Sphenacodontidae (Greek: "wedge point tooth family") is an extinct family of small to large, advanced, carnivorous, Late Pennsylvanian to middle Permian pelycosaurs. The most recent one, ''Dimetrodon angelensis'', is from the late Kungurian or ...

, which includes the better-known '' Dimetrodon'' from the Southwestern United States. The maxilla was first attributed to an early

diapsid Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The group first appeared about three hundred million years a ...

reptile in 1857, and later a

crocodylomorph Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. During Mesozoic and early Cenozoic times, cro ...

in 1869, before finally being identified as a sphenacodont synapsid in 1899, a classification that still holds today. A species of the

hadrosaur Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which incl ...

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 ...

Hypsibema ''Hypsibema'' is a little-known genus of dinosaur from the Late Cretaceous (Campanian stage, around 75 million years ago). Its giant fossils were found in the U.S. states of North Carolina and possibly Missouri. It is believed to be a hadro ...

'', '' H. missouriensis'', is also called '' Neosaurus'', although because the name was already in use, that species was renamed ''

Parrosaurus ''Hypsibema missouriensis'' (; originally ''Neosaurus missouriensis'', first renamed to ''Parrosaurus missouriensis'', also spelled ''Hypsibema missouriense'') is a species of plant-eating dinosaur in the genus '' Hypsibema'', and the state din ...

'' before being reassigned to ''Hypsibema''.

References

Sphenacodontidae Prehistoric synapsid genera Carboniferous synapsids Cisuralian synapsids of Europe Carboniferous France Permian France Fossils of France Fossil taxa described in 1923 Taxa named by Franz Nopcsa von Felső-Szilvás {{Paleo-synapsid-stub