''Rastodon'' is an extinct genus of dicynodont. Uniquely among dicynodonts, its tusks curve forward. The type and only species is ''R. procurvidens''.
Etymology
''Rastodon'' is derived from the
Rio do Rasto Formation
The Rio do Rasto Formation is a Late Permian sedimentary geological formation in the South Region, Brazil, South Region of Brazil. The official name is Rio do Rasto, although in some publications it appears as ''Rio do Rastro''.
The strata were d ...
, where its remains were found, and the Greek word for "tooth". The species name, ''R. procurvidens'', means "curved forward tooth" and describes its uniquely shaped teeth.
Provenance
Only a single specimen of ''Rastodon'' has been discovered so far. It comes from
Guadalupian
The Guadalupian is the second and middle Series (stratigraphy), series/Epoch (geology), epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico an ...
deposits found at an outcrop of the Rio do Rasto Formation at the Boqueirão Farm, in the municipality of São Gabriel, Rio Grande do Sul, Brazil. .
Description
''Rastodon'' is a fairly typical dicynodont. It bore a beaked head with a single pair of tusks and a
keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. It is the key structural material making up Scale (anatomy), scales, hair, Nail (anatomy), nails, feathers, horn (anatomy), horns, claws, Hoof, hoove ...
-covered nasal boss. However, it does possess several distinctive traits, of which its
anteriorly
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Thi ...
-curved tusks are the most distinctive. Furthermore, its skull is relatively long and shallow compared to its close relatives. Its tusks contacted the lower jaw during propalinal
mastication
Chewing or mastication is the process by which food is comminution, crushed and ground by the teeth. It is the first step in the process of digestion, allowing a greater surface area for digestive enzymes to break down the foods.
During the mast ...
.
Classification
''Rastodon'' has been recovered as the basalmost bidentalian dicynodont.
However, the phylogenetic position of ''Rastodon'' is contentious, for it has also been recovered as the basalmost emydopoid dicynodont.
See also
*
List of synapsids
References
{{Taxonbar, from=Q25685697
Anomodont genera
Dicynodontia
Prehistoric synapsids of South America
Permian animals of South America
Permian Brazil
Fossils of Brazil
Paraná Basin
Fossil taxa described in 2016