As they plowed a pasture in the spring of 2001 to plant peanuts, Bruce and Allan Tyner of Newberry looked forward to a good harvest. They sure weren’t thinking about rhinoceroses. But after their plow turned up broken bits of what appeared to be bones from a large animal, they called Richard Hulbert, manager of the Florida Museum of Natural History’s vertebrate paleontology collection. He recognized some of the pieces as fragments of fossilized rhino bones and teeth.
The Tyners generously set aside the boneproducing region of their field and invited museum staff and volunteers to dig away, with the fossils they found going to the museum’s collection. Working primarily in North Florida’s dry spring and fall seasons, for four years museum crews excavated an area of about 900 square feet, carefully digging through clay, sand and loose limestone rubble, until they hit solid limestone at depths varying from 2 to 15 feet below ground.
The resulting “harvest” was more than 5,000 fossils, many of them remarkably complete and beautifully preserved, representing about three dozen animal species that lived in North Florida about eight million years ago. Most of the fossils belong to either a large, hornless rhinoceros paleontologists have named Aphelops or a deer-sized, threetoed horse called Nannippus.
Tyner Farm is located within a 50-by-20-mile-wide stretch of North Florida between High Springs and Dunnellon, in western Alachua and Marion and eastern Levy counties, that has produced many fossil sites ranging in age between 10 and six million years ago. This falls within the later part of what geologists term the Miocene Epoch. This rich fossil record has allowed Florida Museum paleontologists to make detailed analyses of the animals of the interval, and, in a sense, to witness the birth, evolution and extinction of many species. The Tyner Farm specimens, although they have yet to be studied in detail, will add greatly to these studies, as this site falls midway in time between previously known Florida localities and has produced a previously unknown combination of species.
Like most of Florida’s Miocene fossil sites, the Tyner Farm locality began as a sinkhole, a familiar feature of the Florida landscape. As clay washed into the sinkhole, it covered the remains of animals that had fallen into the sinkhole or those of smaller animals such as mice, snakes and lizards that lived and died in the sinkhole. At times portions of the walls cracked and limestone boulders fell to the bottom of the pit, mixing with the bones (crushing some of them) and clay. The combination of the calcium carbonate from the limestone, the moisture-retaining clay, and phosphate grains present in the clay created a stable, chemically perfect environment to preserve the bones and teeth, even those only a few feet below the ground.
The great abundance of rhinoceros fossils at the Tyner Farm site is perhaps surprising to some, but not to paleontologists. Rhinos are common at almost all late Miocene fossil sites in Florida and the rest of North America, Asia, Europe and Africa. In North America, there were two basic types of late Miocene rhinos, a short-legged form called Teleoceras (the skeleton mounted in the Florida Museum Fossil Hall belongs to this type), and the long-legged Aphelops.
Bruce MacFadden, Florida Museum curator of vertebrate paleontology, has analyzed the stable isotopes of carbon and oxygen preserved in the tooth enamel of these two rhinos, and has confirmed earlier ideas based on the anatomical structure of the teeth that Teleoceras predominantly grazed on grasses while Aphelops mostly browsed on the leaves from shrubs, bushes and low tree branches. The Tyner Farm site is one of the few in Florida in which Aphelops outnumbers Teleoceras. More often the situation is reversed. This suggests that the landscape around the sinkhole was primarily covered with brush and trees, with relatively little open grassland.
Other members of the Tyner Farm fossil fauna support this environmental reconstruction. Among those present were tree squirrels, foxes, a tiny deer and other large, browsing herbivores including some of the horses, a ground sloth, a shovel-tusked elephant and a giraffe-like camel with elongated legs and neck. Grass-eating specialists common at other late Miocene sites are either absent or very rare at Tyner Farm.
While not the intended crop envisioned by the Tyners, this bountiful harvest of remarkable fossils collected as a result of plowing for peanuts reminds us that important fossil sites remain to be discovered in Florida, and that many will be discovered in unexpected ways.
Florida Museum of Natural History Vertebrate Paleontology Collection Manager Richard Hulbert specializes in the study of Florida’s fossil mammals. He has authored more than 35 scientific papers and monographs and was the editor and chief author of “The Fossil Vertebrates of Florida” (University Press of Florida, 2001), the definitive work on the subject.