FELIDAE FROM IRVINGTONIAN DEPOSITS AT FAIRMEAD LANDFILL AND IRVINGTON IN CALIFORNIA

In general, felids are rare in Pleistocene localities. When present, felid specimens are often fragmentary and the ability to identify them to species level is difficult due to a lack of diagnostic characters. The sites of Fairmead Landfill and Irvington in central California are significant in that they record a diversity of mid Irvingtonian felids, with some specimens exhibiting intermediate morphologic traits between early and late Pleistocene members of their respective lineages. Fairmead Landfill and Irvington have Homotherium, Smilodon and Panthera in common, with Lynx and Miracinonyx also present at Fairmead Landfill. Fairmead Landfill felid specimens include Homotherium (UCMP 140390 cranium, UCMP 140391 upper canine), Smilodon (MCPC A9 left proximal femur, MCPC A2210 cranium), Miracinonyx (UCMP 140618 maxilla fragment with P4), Panthera (MCPC A2200 partial cranium), and Lynx rufus (MCPC A2198 left proximal ulna, MCPC A2199 left proximal ulna). Irvington specimens include Homotherium (UCMP 39228 partial cranium), Smilodon (UCMP 38338 posterior cranium, UCMP 67859 left dentary with partial m1), and Panthera (UCMP 71237, juvenile jaw with p3-m1). Lynx from Fairmead Landfill is indistinguishable from modern specimens of bobcat. The Miracinonyx agrees morphologically with mid Pleistocene specimens of the taxon. Panthera from both Irvington and Fairmead Landfill share many similarities with Panthera onca, although further evaluation is necessary to resolve some observed differences in comparison to the extant species. The Homotherium crania from Irvington (UCMP 39228) and Fairmead Landfill (140390) compare well to Homotherium serum from Friesenhahn Cave, Texas, but the presence of an internal root (protoradix) on the P4, a primitive character, precludes their assignment to the late Pleistocene taxon. The Fairmead Landfill Smilodon cranium (MCPC A2210) is morphologically intermediate between early Pleistocene Smilodon gracilis and late Pleistocene Smilodon fatalis. The Fairmead Landfill cranium compares best with Smilodon crania from the Irvingtonian Camelot fauna of South Carolina. Overall, Fairmead Landfill and Irvington represent diverse felid records, with evolutionarily transitional features present in some members.