The last erythrosuchid—a revision of Chalishevia cothurnata from the late Middle Triassic of European Russia

BUTLER, RICHARD; SENNIKOV, ANDREY; EZCURRA, MARTIN; GOWER, DAVID

ACTA PALAEONTOLOGICA POLONICA

INST PALEOBIOLOGII PAN

Año: 2019 vol. 64 p. 757 - 774

0567-7920

Erythrosuchidae is a clade of early archosauriform reptiles that were large-bodied, hypercarnivorous, possibly apex predatorsin late Early and Middle Triassic ecosystems following the Permo-Triassic mass extinction. Chalishevia cothurnatafrom the late Middle Triassic (Ladinian) of Russia, is the stratigraphically youngest known erythrosuchid species, butthe holotype and referred material of this taxon has received little study. Here, we provide the first detailed anatomicaldescription of C. cothurnata, including comparisons to other erythrosuchids. Although known from relatively fragmentarymaterial, the anatomy of C. cothurnata is distinctive, including an autapomorphic strongly slanted ventral border ofthe antorbital fossa. The presence of a large accessory opening (the ?accessory antorbital fenestra?) in the skull betweenthe premaxilla, nasal and maxilla, together with the inferred presence of a narrow postnarial process of the premaxillathat articulated with a slot on the nasal, provides strong evidence for a sister taxon relationship between C. cothurnataand the erythrosuchid Shansisuchus shansisuchus from the early Middle Triassic (Anisian) of China. The inferred basalskull length of C. cothurnata was approximately 80 cm, making it one of the largest erythrosuchids known.