Early Pliocene Deer from the Gray Fossil Site, Appalachian Highlands, Tennessee, USA

Abstract

The Early Pliocene age Gray Fossil Site (GFS) of northeastern Tennessee is well-known for its diverse and abundant fauna and flora. Perissodactyls, including tapirs and rhinos, are by far the most common large mammals at the site. The only artiodactyls noted from GFS so far are rare remains of several peccary species and a few camelid specimens. This paper describes the first remains of deer from the site, which include a partial juvenile maxilla, an isolated molar, and postcranial elements including humerus, tibiae, astragalus, calcaneum, and phalanges. Comparisons were made to a wide range of modern and fossil cervids, utilizing both qualitative comparisons and quantitative analyses based on measurements from the upper dentition and postcranial elements. The GFS cervid specimens are remarkably similar in both morphology and size to contemporaneous records of the monotypic genus Eocoileus (E. gentryorum) from the Early Pliocene of Florida, which supports taxonomic assignment to that species here. Eocoileus from the Early Pliocene of Tennessee and Florida are generally smaller than extant and fossil cervids in North and Central America studied here, with the exception of Key deer (Odocoileus virginianus clavium), Yucatan brown brocket deer (O. pandora), and Central American red brocket deer (Mazama temama). Dated to 4.9-4.5 Ma, the GFS deer are among the earliest records of the family in North America and combined with similar age occurrences from Florida and Washington these indicate deer dispersed rapidly across the continent in the latest Miocene or Early Pliocene. Overall similarity of the Eocoileus specimens to modern deer (Odocoileus spp.) suggest the former occupied comparable niches, being versatile browsers well-suited to occupy a broad range of habitats. The GFS deer records suggest deer have filled a similar role in the forests of the Appalachian region for nearly 5 million years, persisting through dramatic changes in climate and biota over time.