Late Miocene Tapirus (Mammlia, Perissodactyla) from Florida, With Description of a New Species, Tapirus webbi

Abstract

Tapirus webbi n. sp. is a relatively large tapir from north-central Florida with a chronologic range of very late Clarendonian (Cl3) to very early Hemphillian (Hh1), or ca. 9.5 to 7.5 Ma. It is about the size of extant Tapirus indicus but with longer limbs. Tapirus webbi differs from Tapirus johnsoni (Cl3 of Nebraska) by its larger size, relatively shorter diastema, thicker nasal, and better developed transverse lophs on premolars. Tapirus webbi is more similar to Tapirus simpsoni from the late early Hemphillian (Hh2, ca. 7 Ma) of Nebraska, but differs in having narrower upper premolars and weaker transverse lophs on P1 and P2. Tapirus webbi differs from North American Plio-Pleistocene species such as Tapirus veroensis and Tapirus haysii in its polygonal (not triangular) interparietal, spicular posterior lacrimal process, relatively narrow P2-M3, and lack of an extensive meatal diverticulum fossa on the dorsal surface of the nasal. In Florida, Hh2 Tapirus is known only from relatively incomplete specimens, but at least two species are represented, both of significantly smaller size than Tapirus webbi or Tapirus simpsoni. One appears to be the dwarf Tapirus polkensis (Olsen), previously known from the very late Hemphillian (Hh4) in Florida and the Hemphillian of Tennessee (referred specimens from Nebraska need to be reexamined). Previous interpretations that the age of T. polkensis is middle Miocene are incorrect; its chronologic range in Florida is Hh2 to Hh4 based on direct association with biochronologic indicator taxa such as Neohipparion eurystyle, Dinohippus mexicanus and Agriotherium schneideri. The second species of Hh2 Tapirus from Florida is of moderate size and similar in some respects to Tapirus haysii and Tapirus veroensis (e.g., triangular interparietal), but it retains some primitive dental character states, such as a labial cingulum and small parastyles on the upper cheek teeth.