Easternmost occurrences of Neocnus (Mammalia, Pilosa, Megalonychidae) from the late Pleistocene–early Holocene of the Dominican Republic (Hispaniola)

Abstract

ABSTRACTFossil sloths from Hispaniola are predominantly represented by records from Haiti. Recent exploration of underwater caves in the Dominican Republic has produced many new sloth specimens, including specimens from two sites that represent the easternmost record for the genus Neocnus. Upper Pleistocene specimens from the localities of Padre Nuestro and Oleg’s Bat House are considered to be N. cf. dousman, based on size and comparison with other Neocnus specimens; they differ strongly from those of Acratocnus and Parocnus. Padre Nuestro produced a right radius and a right femur. The Oleg’s Bat House specimen is a partial skeleton comprising four vertebrae, first ribs with fused sternebrae, a complete pelvis, a scaphoid, and a phalanx. The Oleg’s Bat House specimen also demonstrates a developmental pathology, with the preservation of a cervical rib in association with a vertebra that morphologically is more akin to a thoracic than a cervical vertebra. The pelvis exhibits a number of morphological characteristics that distinguish it from the other island sloths: flattening of the sacral crests and the shape and orientation of the iliac blades. The distal radius and scaphoid morphology indicate a greater range of wrist motion in Neocnus versus that of Parocnus and likely made this sloth more arboreally capable than the more terrestrial Parocnus.