Hidden beneath Tennessee soil for millions of years, a fossil of a massive salamander has emerged — and it’s changing how we understand Appalachian biodiversity.
Key Points at a Glance
- ETSU scientists uncovered Dynamognathus robertsoni, a giant burrowing salamander from ancient Appalachia
- The fossil reveals that powerful plethodontid salamanders were once widespread in North America
- This discovery could reshape theories on how Appalachian salamanders evolved
- The salamander’s name honors a dedicated local fossil hunter and volunteer
In a lush forest of ancient Appalachia, a creature nearly the size of a small cat once tunneled through the soil with jaws strong enough to rival modern predators. Now, scientists from East Tennessee State University (ETSU) have brought that creature back into the spotlight — at least scientifically.
The fossilized remains of Dynamognathus robertsoni, an extinct salamander roughly 16 inches long, were unearthed near ETSU’s Gray Fossil Site. The salamander ranks among the largest ever discovered from the lungless Plethodontidae family — a group known today for its small, cryptic stream dwellers.
“Finding something this big and this powerful in ancient Tennessee was an eye-opener,” said Davis Gunnin, lead author and Assistant Collections Manager at ETSU. “It shows us that large burrowing salamanders like this weren’t just rare oddities — they may have shaped entire ecosystems.”
Named for its “powerful jaw” — from the Greek Dynamognathus — the creature also carries a tribute in its species name, robertsoni, honoring volunteer Wayne Robertson, who discovered the fossil and has sifted through more than 50 tons of fossil-rich sediment since 2000.
Today, Tennessee is a hotbed for salamander diversity, home to over 50 species — one-eighth of the world’s known species. Scientists have long speculated how this richness evolved. The discovery of D. robertsoni helps answer that question: large, ancestral predators may have driven the explosive diversification of smaller, more specialized salamanders like dusky salamanders, shaping entire Appalachian amphibian lineages.
The fossil pushes back against long-held views that burrowing salamanders like Alabama’s Red Hills salamander were evolutionary outliers. Instead, it suggests they once ranged widely, playing crucial ecological roles across what is now the southeastern U.S.
“The Pleistocene cooling likely pushed these giants south,” said Dr. Joshua Samuels, Head Curator at ETSU. “But their ancient northern presence shows just how dynamic salamander evolution has been.”
As climate and terrain shifted, these ancient giants may have faded, leaving behind a thriving legacy of diversity. The study, published in Historical Biology, not only rewrites the evolutionary map of Appalachia — it cements ETSU’s role as a leader in paleo-discovery.
“From volunteers to researchers, this find is a testament to curiosity, persistence, and the stories still buried in Appalachian soil,” said Dr. Blaine Schubert, Director of the Gray Fossil Site & Museum.
Source: East Tennessee State University
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