It took only 10 minutes for paleontologists to dig up a scientifically important tortoise fossil this fall when a group of science writers visited the Florida Museum of Natural History's Thomas Farm site. Elsewhere, you might have to dig for hours to find anything of value. The 18 million-year-old site north of Gainesville is one of the most species-rich vertebrate fossil locations in the world, and the best Early Miocene site in North America, says site manager David Steadman, an ornithologist at the museum. "Florida is a paleontologist's toybox," he says.
Hundreds of thousands of fossils of modern and extinct birds, lizards, alligators, frogs, toads, bats, rodents, bear-dogs (yes!), camels, rhinos and other mammals, including three species of small, three-toed horses (Archaeohippus blackbergi, Parahippus leonensis and Anchitherium clarencei), have been unearthed at this site going back to when a farmer started piling up old bones that got in his way as he dug for a well there in the 1930s. Such discard heaps are called spoils piles, and amateur and professional paleontologists often toss their less intriguing dirt or busted, boring finds onto such heaps for kids and other visitors to paw through in case anything important was missed. Museum curators and other paleontologists dig now at Thomas Farm, but most of the work is done by volunteers, who can get up to speed in about two hours of training on how to non-destructively remove some of the most fragile now-blackened fossils, especially skulls, from gray layers of sand.
As happens a lot in life, the animals in their pre-fossil stage didn't mean to die at this site. Many fell into what was then a 90-foot-deep sinkhole where the farm is now located. The smaller crawlers and flyers that fossilized there were likely pooped, coughed or upchucked into the hole by predators roosting near its lip. For the past few decades, Museum teams have used little screwdrivers to dig down in 10-centimeter intervals to look for fossils in meter-square patches of a grid they've laid over the sinkhole. The hole filled up fast in geologic time, so all the fossil life in it is about the same age.
The first short video below features Steadman and Richard Hulbert, an authority on the Farm's fossil horses and manager of collections at the Museum, giving the group of visitors an introduction to Thomas Farm. He explains why you wouldn't want to try to go there to steal fossils.
The next video below shows Hulbert and Steadman finding a mammal metatarsal (a foot bone, probably from a mini-horse) in just a few minutes of digging, and then finding a diagnostic piece of a fossil tortoise's carapace, a "neural," of scientific interest.
Finally, I shot video below of Jonathan Bloch, associate curator of vertebrate paleontology at the Museum, helping a visitor sort out which of her pulls from the spoils pile would be the "coolest" to a paleontologist. We all got to walk away with a bag of fossils.
Here are some other images I took at the site.
Credit for all images and photos: Robin Lloyd