Gray Fossil Site facts for kids
The Gray Fossil Site is an amazing place in Gray, Tennessee, where scientists have found many ancient fossils. These fossils are between 4.5 and 4.9 million years old! That's a really long time ago, during a period called the Early Pliocene Epoch.
This special site was found by accident in May 2000, when workers were building a road. Local leaders quickly realized how important the discovery was. They decided to protect the site for scientists to study and for everyone to learn from. Now, the Gray Fossil Site is part of East Tennessee State University. In 2007, the Gray Fossil Site & Museum opened there, so visitors can see these incredible discoveries.
Millions of years ago, the Gray Fossil Site was a pond inside a sinkhole. This sinkhole was surrounded by a warm, wet forest. The fossils found here tell us about the ancient plants and animals that lived and died in this special place.
The Gray Fossil Site is the first of its kind found in the Appalachian Mountains. It gives us a unique look into the distant past. Scientists have made many surprising discoveries here. They have found new types of red panda, rhinoceros, pond turtle, and even a new kind of hickory tree. It's also home to the largest collection of tapir fossils ever found!
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How the Fossil Site Formed
The Gray Fossil Site is like a giant time capsule. It's made of layers of clay and silt that settled at the bottom of an ancient lake. This lake formed inside a sinkhole. The area of the fossil site is about 220 meters long and 180 meters wide. It goes deep into the ground, from about 7 meters to 39 meters! The fossils inside are plentiful and often incredibly well-preserved.
The site sits on top of older rocks called the Knox Group. These rocks are mostly limestone. Water flowing through cracks in these rocks creates caves and sinkholes. This type of landscape is called karst topography. The sinkhole at the Gray Fossil Site formed from several smaller collapses that eventually made one big basin. Large rocks found in the lake sediments show that the sinkhole once had tall walls or overhangs. Sometimes, pieces of rock would break off and fall into the lake.
Based on the mammal fossils found, scientists believe the main fossil layers are between 4.5 and 4.9 million years old. This was during the Early Pliocene Epoch. There's also some evidence from deeper drills that even older deposits might be hidden further down. These older layers would be from earlier stages of the sinkhole's formation.
Discovering the Past: History of the Site
In May 2000, construction workers found the fossil-rich site while building a road near Gray, Tennessee. As people realized how special these fossils were, the local community worked hard to save the site. In September 2000, the Governor of Tennessee, Don Sundquist, announced that the road project would be moved. This meant the fossil site could be saved for research and education.
The Gray Fossil Site then became a project of East Tennessee State University. The university hired paleontologists (scientists who study fossils) and geologists (scientists who study rocks and Earth's history). They started a new Department of Geosciences. The university also created the Don Sundquist Center of Excellence in Paleontology. They began building a museum right at the site. This museum would have research labs and exhibits for visitors. The museum first opened in August 2007. It's now simply known as the Gray Fossil Site & Museum.
Ancient Environment: What it Was Like
Millions of years ago, the Gray Fossil Site was a lake or pond surrounded by a thick forest. This ancient lake was full of different water animals. These included fish, pond turtles, salamanders, beavers, and even alligators.
Plant fossils, especially pollen, show us what the forest was like. It had many oak, hickory, and pine trees. There were also different kinds of herbaceous plants (plants with soft stems). Scientists have different ideas about how dense this forest was. Some think it was a moderately thick forest. Others believe it might have been more open, like a woodland. This could be because of large plant-eating animals, frequent fires, or dry periods.
A study in 2020 used fossil mammal teeth to figure out the ancient climate. They estimated the average yearly temperature was about 16.8°C. This is similar to modern-day Atlanta, GA. The yearly rainfall was about 1,343mm, like modern-day Tampa, Florida. The coldest month's lowest temperature was around 2.6°C. These findings match earlier ideas that the site had a warmer and wetter climate than East Tennessee today. This is supported by finding warm-climate animals and plants like alligators, tupelo trees, and Corylopsis.
Many of the ancient animals and plants from the Gray Fossil Site are related to species found in Europe and Asia today. These include red pandas, European badgers, Chinese moonseed, and Corylopsis. This suggests that during the Early Pliocene, eastern North America was connected to Eurasia in a way that allowed animals and plants to move between continents.
Amazing Fossils Found Here
The Gray Fossil Site has a huge collection of well-preserved fossils. It's the only fossil site in the Appalachian region from around the time between the Miocene and Pliocene Epochs. This makes it a special window into this ancient time.
Fish Fossils
So far, all the fish fossils found at the Gray Fossil Site belong to the family Centrarchidae.
Amphibian Fossils
- Salamanders: Several types have been found, including Ambystoma, Desmognathus, Notophthalmus, and Plethodon. These are the oldest known members of their families in the Appalachian mountains. This region is famous for its many modern salamander species.
- Frogs: Many types of frogs have been found, including Rana.
Reptile Fossils
- Alligators: Several well-preserved alligator fossils have been found. They seem to be a different type than alligators we know today.
- Lizards: Identified lizards include skinks, anguids, and helodermatids.
- Snakes: The most common snakes are colubrids. Several species have been found, including a unique fossil species called Zilantophis schuberti. Viperids (venomous snakes) are also present.
- Turtles: This is the most diverse group of reptiles at the site. It includes several types of box turtles, painted turtles, slider turtles, snapping turtles, and tortoises. Two species found here are only known from the Gray Site: the musk turtle Sternotherus palaeodorus and the slider turtle Trachemys haugrudi.
Bird Fossils
A study in 2011 found several families of birds at the Gray Fossil Site. The most common bird fossils were ducks.
Mammal Fossils
Odd-toed Hoofed Mammals (Perissodactyls)
- Tapirus polkensis (dwarf tapir): The Gray Fossil Site has the largest population of tapir fossils ever found. It includes tapirs of all ages, from very young babies to old adults.
- Teleoceras aepysoma (rhinoceros): Several rhino fossils are known, including two almost complete skeletons. In 2019, the rhinos from Gray Fossil Site were identified as a new species. They were named the "high-bodied" Teleoceras because their front legs were longer than other species.
- Cormohipparion emslei (three-toed horse)
Even-toed Hoofed Mammals (Artiodactyls)
- Peccaries: Two species have been found: Mylohyus elmorei and Prosthennops serus.
- Pediomeryx.
- Camel, possibly Megatylopus
Carnivores
- Pristinailurus bristoli (red panda): This was named as a new species in 2004. Two almost complete skeletons make this one of the best-known fossil pandas.
- Arctomeles dimolodontus (Eurasian badger): This species was named along with the Gray Fossil Site panda in 2004.
- Gulo sudorus (wolverine): This is the oldest known fossil wolverine. It was named the "sweaty wolverine" because the ancient climate of Gray was much warmer than where modern wolverines live.
- Plionarctos (short-faced bear).
- Saber-toothed cat, possibly Machairodus.
- Buisnictis breviramus (skunk)
Elephants (Proboscidea)
- Mastodon: This is likely a new species. Several fossils have been found, including one almost complete and very large skeleton. Earlier findings of elephant-like fossils at Gray were first thought to be a gomphothere.
Rodents
- Several species, including beavers, packrats, and mice.
Rabbits and Hares (Lagomorphs)
- Two species of extinct rabbits.
Bats
- Two species of vespertilionid bats.
Shrews and Moles (Eulipotyphla)
- Several species of shrews and moles.
Sloths (Xenarthra)
- An unknown species of megalonychid sloth.
Invertebrate Fossils
Water-dwelling invertebrates found at the Gray Fossil Site include ostracods (tiny crustaceans), snails, and small clams. Insects have also been found from fossilized outer skeletons and trace fossils (like tracks or burrows). These include at least four different families of beetles.
Plant Fossils
Plant fossils at the Gray Fossil Site include pollen, leaves, wood, fruits, seeds, and other parts. They represent many different types of plants. These include flowering plants, conifers (like pine trees), ferns, lycophytes, and bryophytes (like mosses). The forest was mostly made up of various trees and shrubs. The most common were hickory, oak, and pine.
Several new, extinct plant species have been identified at the Gray Fossil Site:
- Carya tennesseensis (hickory)
- Sinomenium macrocarpum (moonseed)
- Staphylea levisemia (bladdernut)
- Three species of Vitis (grapes)
- Corylopsis grisea (witch hazel)
- Cavilignum pratchettii, which is the first extinct genus (a larger group of species) of plant found at the Gray Fossil Site.
Algae Fossils
Tiny algal fossils have been found. They include many freshwater species. One previously unknown extinct species, Stigmozygodites grayensis, was named from the Gray Fossil Site in 2013.
Fungi Fossils
Several types of fungi have been identified from tiny fossil remains of fungal tissue and fruiting bodies.
