Rastodon
From Wikipedia, the free encyclopedia
| Rastodon | |
|---|---|
 | |
| Artist's interpretation of Rastodon | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | Therapsida |
| Clade: | †Anomodontia |
| Clade: | †Dicynodontia |
| Family: | †Kingoriidae |
| Genus: | †Rastodon Boos et al. 2016 |
| Species: | †R. procurvidens |
| Binomial name | |
| †Rastodon procurvidens Boos et al. 2016 | |
Rastodon is a genus of dicynodont, an extinct group of herbivorous therapsids (the group to which modern mammals belong) from the Guadalupian (middle Permian) of Brazil. The type and only species is R. procurvidens, named in 2016 for its forward-curving tusks, unique among dicynodonts. Rastodon is one of the only dicynodonts known from the Permian period of South America. Rastodon was initially described as the earliest member of Bidentalia, a derived group of dicynodonts, and though this relationship was regarded with some scepticism, it was not until 2025 that the specimen was re-examined and reinterpreted as a member of the dicynodont family Kingoriidae.
Etymology
The single specimen of Rastodon was discovered in an outcrop of the Rio do Rasto Formation at the Boqueirão Farm, in the municipality of São Gabriel, Rio Grande do Sul, Brazil. This locality is assigned to the Morro Pelado Member of the formation, which has been roughly dated to the Guadalupian, or the middle Permian period.[1]
The genus name Rastodon is derived from the Rio do Rasto Formation, where its fossils have been found, and the Greek word for "tooth". The species name, R. procurvidens, means "curved forward tooth" and describes the forward-pointing shape of its tusks, unusual amongst dicynodonts.[1]
Description
Like other dicynodonts, Rastodon had beaked jaws sporting only a single pair of tusk-like caniniform teeth (i.e. canine-like) and a keratin-covered nasal boss. Its "tusks" are among its most distinctive features, which uniquely curve forwards (anteriorly), and are positioned in a pocket or embayment the lateral bony wall of the caniniform process of the maxilla, rather than erupting below them as in most dicynodonts, obscuring them from view externally. Furthermore, its skull is relatively long and shallow compared to its close relatives. Its tusks contacted the lower jaw during propalinal mastication.[1][2]
