Body mass estimation for †Cyonasua (Procyonidae, Carnivora) and related taxa based on postcranial skeleton

Abstract

Procyonidae were the first northern placental carnivorans that reached the Neotropics. They are represented by two extinct genera: †Cyonasua and †Chapalmalania (late Miocene – early Pleistocene). Postcranial elements are only known for †Cyonasua and related taxa (†Parahyaenodon argentinus and †Tetraprothomo argentinus). To obtain highly reliable allometric equations for body mass estimations of fossil procyonids, we performed least squares regressions (multiple and bivariate lineal models) using 51 postcranial linear measurements. The extant sample included 124 taxa corresponding to nine families of Carnivora, with body mass data from the literature. We obtained about 63 equations from diverse combinations of postcranial measurements; 14 of them were selected using several reliability indexes as criteria. Our results show that body masses calculated for †Cyonasua range between 12.63 and 28.45 kg, †P. argentinus was estimated at 14.41 kg, while †T. argentinus at 25.31 kg. Thus, the body mass of †Cyonasua would have been at least twice as high as the mean of the extant procyonid Procyon cancrivorus. †Cyonasua was probably able to fend off predators and quite capable of climbing slowly on thick-enough branches. Other palaeoecological and palaeobiological inferences are discussed.