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Cluster of mastodon specimens found at Gray Fossil Site

 

ETSU paleontologists were thrilled when they wrapped up last year’s digging season at the Gray Fossil Site with the discovery of a mastodon.  More excitement abounds this year, as even more of the gigantic creatures have been located.

When the early part of the 2015 digging season was relatively uneventful, scientists turned their attention to the original area where Tennessee Department of Transportation workers found ivory during a roadwork project in 2001, which led to the establishment of the Gray Fossil Site.

“Not only did we find exactly where they’d hit ivory, but they’d hit an intact piece of really long tusk,” said Dr. Steven Wallace, a professor in the ETSU Department of Geosciences.  “That led back to a skull, which led back to part of the spinal column, and it just kept going.  What’s neat is the teeth look a lot like mastodon, but the jaws look a lot like a shovel-tusked elephant, so it’s this weird, intermediate, transitional thing.  We’re not really sure what it is, so when we say ‘mastodon’ or ‘elephant,’ we use those terms loosely.”

Workers dug a large hole around the original specimen and created the largest jacket – a protective covering used for moving sections of material from the field to the lab – in the history of the Gray site.  When they expanded the dig to roll the jacket over, they ran into the teeth of another individual.

“As we started working again this spring, we ran into additional pieces of ivory and additional sets of teeth, and right now, I think we’re up to at least three, and maybe four, individuals,” Wallace said.  “We’re finding fairly large sections of ivory in different portions where we’re digging, so there definitely is a cluster of ‘elephants’ or ‘mastodons’ in this one spot.  It’s interesting to think that we’ve dug there for 15 years and all we’ve found are scraps, and now all at once, we’re finding this pile.”

Wallace explained that previous finds at the site – from tapirs to turtles and frogs – have supported the assumption that the site formed through day-to-day activities at a Miocene Era (4.5-7 million years ago) watering hole.  This discovery of the large mammals, though, could tell a more dramatic story than that of many of the other animals.

“It was just a watering hole,” he said, “but the fact that all these elephants are clustered in one spot does make you wonder – did something different happen there?  Did they get in and get stuck? Maybe they were so big they couldn’t get out, and they were indeed trapped.  It could’ve been that a wall collapsed along the side of the actual pond, and they slid in with it, because there are a lot of boulders in with them.

“It’s hard to tell right now, and until we get them all out, we’re not going to know for sure.  It’s going to be an interesting story, but it’s going to take us years to dig all of this out.”

To illustrate the size of the initial mastodon (also spelled mastodont) found last year, Wallace recalled a triceratops skeleton, on loan from another museum, which was displayed several years ago in the lobby of the ETSU and General Shale Natural History Museum and Visitor Center at the Gray Fossil Site. 

“This thing would’ve dwarfed the triceratops,” he said.

The lower jaw of the mastodon is nearly five feet long after being pieced together, and while the lower tusks are only about one foot long, the upper tusks are expected to reach between 10 and 12 feet in length once they are completed.  Unlike the tusks of another elephant-like creature, the mammoth, which were longer and curvy, those of the specimen at Gray appear to have a slight, gentle curve.  In addition, Wallace predicts that this specimen will have some intriguing spinal features.

“I think when the skull’s put together, that’s going to be a really impressive display, let alone the dream we all have – when the skeleton’s done – of mounting this thing,” he said.  “It would be wonderful to have this big elephant standing out there and be able to say, ‘Yes, that’s from right over there.  We found it right here.’”

This find may help scientists piece together more of the historic picture of elephants.

“This one’s really neat, because most elephant specimens from the late Miocene are usually fragmentary,” Wallace said.  “They just get pieces of teeth, jaws, tusk – maybe bits and pieces of a skeleton – but it’s super-rare to get a whole skeleton.

“What’s important is that because it seems to be this transitional form, I think it’s going to help us figure out what was going on in the evolution of the elephants at that time.  There were a lot of interesting groups then, and we don’t really understand how they were related to each other.  So to find something that’s kind of intermediate is really nice – if we can’t explain the whole tree, at least we can explain a branch.”

In the process of digging around this large species, the scientists at Gray have discovered several other interesting things.  Parts of a rhinoceros have been found “draped” over the mastodon, and in sifting through the material surrounding the animal, at least two skulls of a particular toad have been found to match bits and pieces of a new specimen that Dr. Jim Mead, ETSU professor emeritus of Geosciences, and a former student are working to identify.

The Gray Fossil Site’s third horse tooth has been unearthed, as have pieces of additional specimens of animals already found at the site, including turtle, sloth and peccary, a pig-like animal.

“We found a hand bone that seems to be from some sort of a giant weasel … the size of a small bear,” Wallace said.  “It’s going to be something really big, so I’m excited about that.

“Gray is really terrible about doing that to us – it has these teases all the time.  You get a bit or piece and you have an idea of what it is, but what’s nice, even though it teases us in that way, is that the more you dig, sooner or later, you do find a skeleton.”

And ETSU’s scientists are just getting started.  Wallace emphasizes that the Gray Fossil Site is only 15 years old, as compared to other sites like the La Brea Tar Pits in California, where paleontologists have been digging for over a century and have developed a massive collection of specimens.

“I would hope that after a hundred years, we’ll have a similar collection, but instead of it being dire wolves, it’ll be tapirs,” he said.  “Every time we hit a skeleton, I keep hoping it’ll be that big saber-toothed cat or that big bear.  One of my favorite things to say is that it’s not what we find but what we might find that keeps us digging, and there are some really neat possibilities of things that we could find.

“We have this list of what we have found, a list of what we should find, and a list of what we hope to find, and the ‘hope’ one is the most entertaining.”

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