''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 ecologi ...

temnospondyl within the family Rhinesuchidae. It contains one species, ''Rastosuchus hammeri'', found in the Permian Rio do Rasto Formation of Brazil.

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 descr ...

'' 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 stages ...

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