About Thomas Farm
Thomas Farm is about 8 miles north-northeast of Bell, Gilchrist County, Florida, at 29.9° N, 82.8° W. It is about 45 miles northwest of Gainesville.
Early Miocene Epoch; Early Hemingfordian Land Mammal Age (ca. 18 million years old). The age is estimated from biochronology, which is the comparison of similar species of fossil mammals from site to site. For Thomas Farm, an Early Hemingfordian age is supported by the combined presence of the bear Phoberocyon, the mustelid Leptarctus, the rhinoceros Floridaceras, and the canid Metatomarctus. These four mammals have been found in Early Miocene fossil sites in the western U.S. that have been dated through radiometric and paleomagnetic methods.
The fossils at Thomas Farm are found in alternating beds of clay and calcareous (limestone) sand, with occasional lenses or beds of limestone gravel to boulders in a sandy matrix. Most fossils are from the various sandy layers.
The fossils are found within an ancient sinkhole and associated cave system. Fossils accumulated at Thomas Farm through “natural trap” activity (animals falling into the steep-walled sinkhole and then being unable to leave) or as the discarded prey remains of hawks and owls, or through natural mortality (especially bats that were roosting in the cave).