Field of Science

Chanaresuchus ischigualastensis, a New Proterochampsid from the Late Triassic of Argentina and a Temporal Range Extension for the Genus Chanaresuchus

This is a short communication in the new issue of the Journal of Vertebrate Paleontology. As such there is no abstract available.

Trotteyn, M. J., Martinez, R. N., and O. A. Alcober. 2012. A new proterochampsid Chanaresuchus ischigualastensis (Diapsida, Archosauriformes) in the early Late Triassic Ischigualasto Formation, Argentina. Journal of Vertebrate Paleontology 32:485-489. DOI:10.1080/02724634.2012.645975

The specimen includes much of an articulated skeleton including a well preserved skull. This is the first occurrence of Chanaresuchus outside of the Chanares Formation and marks an extension of the taxon into the Late Triassic. As the authors state, this is interesting because it demonstrates only a species level turnover for the clade between the late Middle and early Late Triassic faunas in the Ischiguasto Basin. Several therapsids also show the same pattern. This also marks the presence of two different proterochampsids in the Ischigualasto Formation.

From the discussion: "PVSJ 567 is assignable to Chanaresuchus on the basis of diagnostic characters shared with Chanaresuchus bonapartei (e.g., skull ornamented by longitudinal crests and depressions on the dorsal surfaces of the premaxillae, maxillae, and nasals; lateral fossa in the centra of presacral vertebrae; low deltopectoral crest on the humerus; absence of phalanges on pedal digit V). PVSJ 567 exhibits several differences from Chanaresuchus bonapartei and can be assigned to a new species, C. ischigualastensis (e.g., basal tubera wide with rostrolateral contour transversely oriented; paroccipital processes distally expanded; articular surface of caudal prezygapophyses elliptical and notably anteriorly developed; astragalus lacking perforations in the posterior sulcus; osteoderms with longitudinal dorsal sulcus).

          

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