''Rastosuchus'' is an extinct genus of

stereospondyl The Stereospondyli are a group of extinct temnospondyl amphibians that existed primarily during the Mesozoic period. They are known from all seven continents and were common components of many Triassic ecosystems, likely filling a similar ecolog ...

temnospondyl Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carb ...

within the family

Rhinesuchidae Rhinesuchidae is a family of tetrapods that lived primarily in the Permian period. They belonged to the broad group Temnospondyli, a successful and diverse collection of semiaquatic tetrapods which modern amphibians are probably descended from. ...

. It contains one species, ''Rastosuchus hammeri'', found in the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ...

Rio do Rasto Formation The Rio do Rasto Formation is a Late Permian sedimentary geological formation in the South Region of Brazil. The official name is Rio do Rasto, although in some publications it appears as ''Rio do Rastro''. Geography It is found mainly in the B ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

History of study

The name ''Rastosuchus hammeri'' was used as early as 1980 and then on several other instances, but because none of these usages formalized the name via a formal description, the name was considered to be a ''

nomen nudum In taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate des ...

'' until formally described by Dias et al. (2020). Some of the material was also previously mentioned without nomenclatural assignment. A partial description of a nearly complete skull now assigned to this taxon was presented by Barberena & Dias (1998), and the phylogenetic position (as the "Serra do Cadeado short-snouted rhinesuchid") was assessed by Eltink et al. (2016). The holotype is a pair of lower jaws because this was the first material informally associated with the name. The genus name refers to the Rio do Rasto Formation, with the common suffix -''suchus'' for 'crocodile.' The species name honors William R. Hammer, who is best known for his work on

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final st ...

n fossil tetrapods.

Anatomy

In addition to the holotype and previously described complete skull, additional material includes fragmentary lower jaws and one partial postcranial skeleton including the pectoral girdle, hindlimb, vertebrae, and ribs. Specimens were collected from several localities and over a number of years. Based on the holotype, ''R. hammeri'' is diagnosed by many features, such as the presence of large teeth on all three coronoid bones, rather than denticles as in other rhinesuchids; a short symphysis; and various contacts between different mandibular bones.

Phylogenetic position

Below is the topology recovered by Eltink et al. (2016):

References

{{Taxonbar, from=Q97482143 Stereospondyls Paraná Basin Permian temnospondyls of South America Fossil taxa described in 2020 Permian temnospondyls