The hand structure of Carnotaurus sastrei (Theropoda, Abelisauridae): implications for hand diversity and evolution in abelisaurids.

Abstract

Carnotaurus sastrei is an abelisaurid dinosaur
from the Late Cretaceous of Argentina that has very reduced,
but robust, forelimbs and derived hands with four digits,
including a large, conical-shaped metacarpal IV lacking an
articulation for a phalanx. The analysis presented in this
work highlights a series of additional autapomorphies of
C. sastrei. For example, the proximal phalanges are longer
than the metacarpals in digits II and III, and digit III
includes only one phalanx besides the ungual. The hand of
Carnotaurus shares several features with those of Aucasaurus
and Majungasaurus, but the hands of the latter genera also
display autapomorphies, indicating that the diversity in abelisaurid
hand structure is similar to the diversity of cranial
protuberances of these dinosaurs.