New Neogene fossil phocid postcranial material from the Atlantic (USA)

Abstract

ABSTRACT To date, the phocid fossil record from the Western Atlantic includes representatives of the subfamilies Monachinae and Phocinae. New partial postcranial bones (humerus, innominate) of true seals from the Meherrin River, Murfreesboro, Hertford County, North Carolina, U.S.A. are morphologically examined in detail. The newly discovered postcranial bones are compared to representatives of other pinnipeds (Phocidae, Otariidae, and Odobenidae) and to representatives from other phocid subfamilies (Cystophorinae, Devinophocinae, Monachinae, and Phocinae). Detailed morphological analyses demonstrate characteristics that are known to be phocid-specific, such as: the humeral deltoid crest extending to half its length, becoming thinner towards the distal portion; short and flattened femur, with a diaphysis that is broader at its distal end; and absence of femoral lesser trochanter. Taxonomic assessment identified the humerus as Phocanella pumila (Subfamily Phocinae), and the three innominate bones (Subfamily Monachinae): Homiphoca capensis, Sarcodectes magnus, and a newly discovered genus and species Seronectes meherrinensis. In the same collection, a fossil femur from the Chesapeake Group, St. Marys Formation, Maryland-Virginia is identified as Homiphoca capensis (Subfamily Phocinae). This study further confirms the likely presence of adaptively diverse phocids from either the subfamily Monachinae or Phocinae in the same locality during the Miocene time.