Before the Dinosaurs, This Massive Salamander-Like Predator Ruled Earth’s Swamps

Fossils unearthed in present-day Namibia tell an intriguing story of tetrapod evolution

An artist’s rendering of Gaiasia jennyae
An artist’s rendering of the creature called Gaiasia jennyae Gabriel Lio

Some 40 million years before the dinosaurs dominated Earth, a different sort of apex predator roamed the Gondwana supercontinent during the late Palaeozoic ice age: a massive, eight foot-long salamander-like creature with an enormous head and powerful fangs.

Roughly 272 million years ago, the creature—named Gaiasia jennyae—inhabited the cool swamps in what is now the Namib desert. It was in this sandy landscape that a fossil of the creature was first discovered in 2015, and four incomplete specimens, including skull and backbone fragments, have been unearthed since.

Analyses of Gaiasia and its fossils, published this week in the journal Nature, reveal the creature as a powerful hunter with an important life history, offering clues about the common ancestors of a variety of other vertebrates.

“When we found this enormous specimen just lying on the outcrop as a giant concretion, it was really shocking,” Claudia Marsicano, a paleontologist at the University of Buenos Aires and a lead author of the study, says in a news release. “I knew just from seeing it that it was something completely different. We were all very excited.”

Gaiasia's two sharp fangs help make it an apex predator in icy swamps.
Gaiasia's sharp fangs helped make it an apex predator in icy swamps.  Marsicano et al.

One of Gaiasia’s most striking features is its head, which has been measured at roughly two feet long. “It's got a big, flat, toilet seat-shaped head, which allows it to open its mouth and suck in prey,” Jason Pardo, a postdoctoral fellow at the Field Museum in Chicago and the study’s co-lead author, says in the news release. “It has these huge fangs, the whole front of the mouth is just giant teeth.”

As a hunter, Gaiasia likely drifted in lakes and swamps waiting to strike, similar to a crocodile, and swam like an eel. The creature could also walk on land, though not very nimbly. As a four-legged vertebrate, it belongs to a class of animals called tetrapods, which “evolved from lobe-finned fishes and gave rise to amphibians, reptiles, birds and mammals,” according to the release.

The fossils’ discovery is especially significant because of its location. When Gaiasia was alive, tetrapods across the globe were evolving differently depending on their geography. Those living closer to the equator were rapidly changing. Most tetrapod fossils that have previously been found represent these equatorial locations.

Researchers unearthed fragments of Gaiasia's ​​​​​​​two foot-long skull.
Researchers unearthed fragments of Gaiasia's two-foot-long skull.  Marsicano et al.

But 300 million years ago, present-day Namibia was located where Antarctica is now. The swamps Gaiasia hunted were likely quite cold, filled with ice and glaciers. That such a massive, archaic creature could survive and thrive in such harsh conditions was a surprise to the researchers. In fact, Gaiasia more closely resembled creatures that were 40 million years older, than it did its tetrapod contemporaries.

“The fact that we found Gaiasia in the far south tells us that there was a flourishing ecosystem that could support these very large predators,” Pardo says in the release. “The more we look, we might find more answers about these major animal groups that we care about, like the ancestors of mammals and modern reptiles.”

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