A new Early Pleistocene North American prairie vole from the Java local fauna of South Dakota, USA

Abstract

ABSTRACT Previously known as Allophaiomys cf pliocaenicus, a new species of Pedomys is described from the early Pleistocene Java local fauna of South Dakota. Biostratigraphic correlations place the fauna between 2.0 and 1.29 Ma. Pedomys javaensis n. sp. is characterised by a first lower molar (m1) with three closed triangles (T) and a simple anteroconid (ACD) with a rare development of buccal re-entrant angle 5 defining an incipient T7. Connections between T5 and the ACD and T4–5 are broad, and the enamel is, on average, slightly positively differentiated. The M3 is simple, with distinct T5 and a relatively deep, posteriorly directed third lingual re-entrant angle. Twenty-two per cent of the Java m1s share morphological characters with Pedomys, prairie voles, suggesting that Pedomys originated from an early Pleistocene North American Allophaiomys-like ancestor. In the calculated ratios of m1 measurements, the new species lies morphologically between the Old World Allophaiomys deucalion and A. pliocaenicus.