Something has been discovered in Tennessee—something that only exists in one museum. It’s something enormous, slightly puzzling, and possibly the first of its kind discovered. Five years after its excavation, it remains incomplete.

The mastodon skeleton slowly taking shape in Tennessee is no secret. Pictures and descriptions of its progress have been posted on social media from the beginning, and while those who are aware of it are intrigued, it hasn’t made many headlines. Yet.

Out of the gray

The Gray Fossil Site near Gray, Tennessee, was found by accident during road construction in 2000. Thanks to the efforts of local people and the state government who recognized the importance of the site, construction halted. A museum was erected several years later. Bits of bones and one shattered tusk were all that had been found when the site was preserved, but the area is proving to be voluminous in its fossil content.

“We used to catalog 1,000 specimens a year—[Individual specimens] could be a tapir, frog, snake, whatever,” Gray Fossil Site Lab and Field Manager Shawn Haugrud explained by phone. But additional volunteers have helped boost the pace: “A couple of years ago before the pandemic, we catalogued 10,000 specimens—so 10 times as many fossils.”

This area is an approximately 5 million-year-old sinkhole. It has preserved a wealth of fossil vertebrates and plants, over 100 species of each to date, from what was once a distinctive ecosystem. And the largest, perhaps most mysterious discovery of them all? The Gray Fossil mastodon.

That’s what it’s called at the moment. Found lying on its side among and underneath boulders, this ancient mammoth relative has the requisite tusks, four limbs, and overall body shape of a mastodon. But it’s different enough to give scientists pause.  When compared to other known North American mastodons—a genus that is, with increasing research and discoveries, beginning to expand—it doesn’t match.

This fossil was the subject of a presentation by Dr. Chris Widga, head curator at the Gray Fossil Site, at the Eighth International Conference on Mammoths and Their Relatives (ICMR) this past October. Unlike massive paleontological conferences, the ICMR is both remarkably small and comparatively new. According to Dick Mol and Dr. Adrian Lister, both renowned mammoth scientists who have been heavily involved in these conferences, the first ICMR was in 1995 and originated as a mammoth-centered conference hosted in Russia. Since then, it has grown into one that includes research about both extinct and extant proboscideans, a family of vertebrates whose prominent feature usually includes a proboscis (a trunk) and encompasses today’s elephants.

The conference is held in a different part of the world every three to four years. At the previous 2017 conference, “India put up a proposal for hosting the 8th conference at Bangalore,” wrote Dr. Raman Sukumar, organizer of this year’s ICMR and honorary professor at the Centre for Ecological Sciences, in an email. “The scientific steering committee of the conference voted overwhelmingly in support of the Indian proposal to host the 8th conference at Bangalore in 2020.” But due to the pandemic, the Indian Institute of Science hosted this online. One hundred thirty-seven people from 27 countries participated.

Not like the others

Showing the Gray Fossil mastodon’s skull in comparison to both earlier and later mastodon species, Widga explained just why they aren’t ready to say exactly what it is they’ve found. Even visually, the differences are immediate.

“The record of early North American mastodons is extremely fragmentary, and the character[istics] that we’ve used to tell them apart, historically, don’t often hold up to modern scrutiny,” he wrote. “This is why it is difficult to fit the Gray mastodon into any existing evolutionary framework. BUT what we do have points to a novel suite of morphological features, suggestive of a new species.”

https://arstechnica.com/?p=1820283