Phylum Chordata | Class Reptilia Rank Genus | |
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Riojasuchus is an extinct genus of quadrupedal crurotarsan archosaur. Riojasuchus is a member of Ornithosuchidae, a family of facultatively bipedal carnivores that were geographically widespread during the Late Triassic. Two other genera, Ornithosuchus and Venaticosuchus, are currently known. The holotype specimen is PVL 3827. It was found in the Los Colorados Formation.
Contents
Discovery and naming
The holotype specimen is PVL 3827, consisting of a mostly complete crania and a partial postcrania. A majority of the postcranial material was preserved. The skeleton was found with others in the upper section of the Los Colorados Formation. Other that the holotype, it is known from three skeletons
Description
The skull of the type specimen is 25 centimetres (9.8 in) long, and has a large, curved snout and short mandibles.
Distinguishing characteristics
Many characteristics were identified by Bonaparte in 1969. They are listed below:
Classification
Riojasuchus is a member of Ornithosuchidae, a family of facultatively bipedal carnivores that were geographically widespread during the Late Triassic. Two other genera, Ornithosuchus and Venaticosuchus, are currently known. The group was originally considered to be related to dinosaurs, before many phylogenetical analysises.
Below is a phylogenetic cladogram by Butler et al. in 2011 showing the cladistics of Archosauriformes, focusing mostly on Pseudosuchia: Clade names follow Nesbitt 2011.
Paleoecology
Fossils of Riojasuchas are found in the Los Colorados Formation, a Late Triassic unit in Argentina, and date to approximately 217 to 215 million years ago. At that age, it is the youngest ornithosuchid known. It lived alongside the protosuchid Hemiprotosuchus; the sphenosuchid Pseudohesperosuchus; the stagonolepidid Neoaetosauroides; the melanorosaurid Strenusaurus; and the riojasaurid Riojasaurus.