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Abstract
ABSTRACT—A giant caseid, Alierasaurus ronchii, gen. et sp. nov., is herein described, based on a partial postcranial skeleton collected from the Permian Cala del Vino Formation (Alghero, Nurra, northwest Sardinia). Despite the highly conservative morphology of ribs and vertebral material, typical of caseids, the very well-preserved foot elements show highly autapomorphic features, warranting assignment of the specimen to a new genus. In particular, the fourth metatarsal is not short and massive, as in other large caseids, and shows a distinct axial region. Finally, the claw-shaped ungual phalanges are autapomorphic in being proportionately very short, with a strong double ventral flexor tubercle positioned very close to the proximal phalangeal rim, and a distal end that is not spatulate, but rather subtriangular in transverse section. Principal component and reduced major axis slope analyses, performed on 10 caseid specimens, suggest that the observed changes in overall shape of metatarsal IV were mainly linked to the enormous body size reached by the Sardinian specimen.
ACKNOWLEDGMENTS
We thank K. D. Angielczyk and W. F. Simpson of the Field Museum of Natural History of Chicago (U.S.A.) and R. L. Cifelli, K. L. Davies, J. Larsen, and A. Thomas of the Sam Noble Oklahoma Museum of Natural History (U.S.A.) for allowing access to specimens under their care and for kind additional assistance. We thank J. Fröbisch and R. Cifelli for their comments and suggestions on earlier versions of the manuscript. P. Cucuzza is thanked for sculpturing and modeling of restored autopodal elements. We further thank reviewers and the Associate Editor for comments that greatly improved the manuscript.
Handling editor: Sean Modesto.
