New seal mandibles belonging to the subfamilies Monachinae and Phocinae discovered in the Neogene of North Carolina (USA)

Abstract

ABSTRACT The fossil record of true seals in the Western Atlantic includes representatives of two subfamilies: Monachinae and Phocinae. The discovery of five unique mandibles from either the late Miocene marine (7.0–6.0 Ma) Eastover Formation or Early Pliocene (5.2–3.4 Ma) Yorktown Formation in North Carolina, USA, present a mixture of characters that are indicative of phocids in either the subfamily Monachinae or Phocinae. These mandibles were collected from the riverbed of the Meherrin River, a tributary of the Chowan River in North Carolina (USA). Detailed morphological analyses compared these newly discovered mandibles to representatives of other pinnipeds (Phocidae, Otariidae, and Odobenidae) and to representatives from phocid subfamilies (Cystophorinae, Devinophocinae, Monachinae, and Phocinae). Based on comprehensive morphological assessment and comparison to fossil and modern taxa, two new Monachinae species are identified: Homiphoca murfreesi and Hadrokirus novotini. Three new Phocinae species were also identified: Phocanella pumila, Leptophoca lenis and a phocine mandible that cannot be assigned to a specific genus or species at this time.