This alligator skull was discovered at the Gray Fossil Site.

Gray Fossil Site

A long, long time ago -- scientists estimate between 4.5 and 7 MILLION years ago -- there was a sinkhole in what we now know as Washington County. Many animals died in this sinkhole, and the bones of those animals did not decompose because they were protected from the elements. The sinkhole eventually filled up, and by the time people came to Tennessee no one knew there had ever been a sinkhole there.

Then, in the year 2000, a road construction crew began digging in the area, came across fossils, and notified state officials. Since that time, paleontologists have been digging up the Gray Fossil Site and making incredible new discoveries. Now there is a natural history museum being built there.

An artist's depiction of life around the sinkhole
There's a lot to talk about when you discuss the Gray Fossil site. Perhaps the best thing to do is to answer the questions most likely to be asked:

1) How old are these fossils?

The fossils found here are believed to be between 4.5 and 7 MILLION years old. That's long after the disappearance of the dinosaurs but long before scientists believe man existed.

In case you are wondering how scientists came up with those years: One of the species whose fossil has been found on the site, the short-legged rhino, is believed to have existed between 4.5 million years ago and 17.5 million years ago. Another species, the short-faced bear, existed between 2 million years ago and 7 million years ago. That puts the age of the entire collection of fossils between 4.5 and 7 million years ago. 
Digging on the site
PHOTO: East Tennessee State University
2) How do these fossils compare to other fossils people have found?

The fossils found here aren't the oldest ever found in the United States, or even the oldest ever found in Tennessee. But the existence of so many different plants and animals in the same place is extraordinary. This is by far the largest collection of Miocene era fossils ever found outside of the Gulf Coast or the far west.

Do you see the alligator skull and arm? This picture was taken before they extracted them from the soil.
PHOTO: East Tennessee State University
3) Why are these fossils so well preserved?

The fossils have been found in an area where the soil is unusually black and rich in organic matter; the dirt in which the paleontologists are digging looks nothing like the red clay that you usually find in the ground at these depths. What scientists believe is that the animals who died in the sinkhole fell to the bottom of it and their bones were well preserved because there was so much decaying plant material also in the sinkhole. (Decaying plant material would have kept out oxygen, which would have decomposed the bones).
This rhinoceros femur bone was found on the site, but it had to be pieced together.
4) How many different types of fossils have been found?

The fossilized remains of more than 60 different types of animals and plants have been found on the site. On the animal side, this includes types that still live in Tennessee (turtles, fish, salamanders, bats) and some that no longer live in Tennessee (rhinos, camels, saber-toothed cats, alligators, elephants). In fact, it took nine weeks, but crews unearthed the entire skeleton of a rhinoceros -- piece by piece.

PHOTO: Friends of the Smithsonian National Zoo
Also, two new species have been discovered on the site: a type of red panda now known in scientific circles as a Pristinailurus bristoli and a badger now called Arctomeles dimolodontus. (Don't worry: you won't have to identify them on the TCAP test.) The red panda might have looked something like this one (shown here).

Workers sift through the dirt.
5) Who's doing all the digging?

The site has been turned over to East Tennessee State University, which has created an entire paleontology program and laboratory as a result of it. The people digging on the site include professors, students, and trained volunteers. It is hard, monotonous work, but the workers get a kick out of sifting through a huge bag of soil and finding a tiny fish vertebra inside. We know that they do because we saw them find a fish vertebra when we were there, and they got excited.

Some of the fossilized turtle shells found at the site
6) How big is the fossil site?

The paleontologists now digging believe they will eventually find fossils in an area four to five acres wide and up to 100 feet deep. By paleontology standards, that's a massive area; they may be digging for decades. So there's no telling what they'll find as they keep going down.
ETSU students at work cleaning fossils

For more information on the Gray Fossil Site, click here.