NEW MAMMALS FROM THE GRAY FOSSIL SITE IN TENNESSEE; PALEOECOLOGICAL IMPLICATIONS AND A REFINED AGE ESTIMATE FOR THE SITE

The Gray Fossil Site (GFS) of northeastern Tennessee has a well-preserved and diverse flora and fauna, and represents one of only a few late Neogene vertebrate fossil sites in eastern North America. The fauna from the site described so far is unlike other faunas of similar age, with tapir (Tapirus polkensis) and rhino (Teleoceras) common and ailurid (Pristinailurus bristoli) and tremarctine bear (Plionarctos) present. Both macro- and microfossils of plants from the site indicate a forested environment was present, which was dominated by oak, hickory, and pine.

Ongoing excavations and extensive screen-washing efforts in recent years have yielded thousands of specimens, including remains of many new mammals. Rodents include two castorids (Castor and Dipoides), six cricetids (Antecalomys, Neotoma, Postcopemys, Repomys, Symmetrodontomys, and an unidentified large species), a dipodid (Sicista), and five sciurids (Eutamias, Glaucomys, Miopetaurista, and two Sciurini). Leporids include Notolagus and Alilepus. Talpids include Parascalops, Mioscalops, Quyania, and an unidentified desman. Additional carnivorans include a new species of wolverine (Gulo), a mephitid (Buisnictis), and a procyonid (Bassariscus). The dromomerycid Pediomeryx is the first ruminant recognized from the site.

Among the new mammals at GFS are a number of taxa that support previous environmental interpretations based on fauna, flora, and isotope records. The presence of tree squirrels, flying squirrels, and a ringtail support the forested interpretation, as does the absence of burrowing rodents. The occurrences of two beaver species and a desman support the presence of year-round water.

Stratigraphic ranges of newly recognized taxa are consistent with an early Pliocene age-constraint for the site and provide a substantially narrower range than previous estimates. Occurrences of Neotoma, Repomys, Symmetrodontomys, Notolagus, Alilepus, Buisnictis, and Pediomeryx along with the rhino Teleoceras all help refine the estimated age range for GFS. The site lacks any taxa restricted to the Miocene or Hemphillian NALMA and has multiple taxa characteristic of the Blancan NALMA. In sum, biostratigraphy based on the mammal fauna suggests the site ranges from 4.9 to 4.5 Ma.