The Giant Amphibian that May Have Feasted on Dinosaurs

​Paleontologists have discovered a thoroughly weird new species of giant amphibian, which thrived in freshwater ecosystems of the Late Triassic period, 230 million years ago. Measuring two meters from head to tail, Metoposaurus algarvensis was a formidable carnivore that dined on fish, reptiles, and perhaps even early dinosaurs.

A comprehensive study about the new species, led by University of Edinburgh paleontologist Steve Brusatte, was published today in the Journal ​of Vertebrate Paleontology.

"The new critter is a temnospondyl, which is a major group of archaic amphibians that lived for well over a hundred million years, and came in all shapes and sizes and diets," Brusatte told me. "Some were quite small and looked like little salamanders, but the biggest were about nine meters in length, which is just astronomical for an amphibian."

Size isn't the only thing these animals had going for them. Fossils collected by Brusatte and his international team—which included paleontologists Richard Butler, Octavio Mateus, and Seb Steyer—also reveal that this animal had a bizarre parabolic curve of a mouth, packed with hundreds of sharp teeth.

"It was almost certainly primarily a fish-eater, although we know from other sites that temnospondyls did interact with big reptiles that would come too close to the water," said Brusatte. "So if you were one of these small primitive dinosaurs just starting to rise up during the Triassic Period, then it would have been wise to avoid venturing too close to the water."

To that point, the water wasn't the only place to watch out for in the Triassic. As I wrote last week regarding another badass late Triassic predator, this era was defined by an unusual abundance of meat-eaters. If ever there was a biosphere that perfectly typified Tennyson's description of nature as being "red in tooth and claw," the late Triassic was it.

Moreover, in addition to this never-ending litany of weird carnivores, the Triassic was also home to the first dinosaurs and mammals. This is the ecological backdrop of the world that shaped Metoposaurus—and that it, in turn, helped shape.

"[O]ur oldest ancestors, and the very oldest dinosaurs, had to deal with these big amphibians during their formative years," Brusatte told me. "The big amphibians were part of the fabric of this ancient world, living almost everywhere around the globe. You would have seen a lot of them if you were a time traveler."

Alas, the temnospondyls did not live the high life forever. The Pangean supercontinent began to rip apart some 200 million years ago, which sparked frequent and violent volcanic eruptions. According to Brusatte, these eruptions were "totally out of scale of anything humans have witnessed."

"They poisoned the atmosphere and led to chaotic swings in climate," he said. "Many animals couldn't cope, including many of the huge amphibians. Most of them died out. But dinosaurs went through relatively unscathed, and in the post apocalyptic world the dinosaurs took over, spread around the globe, developed massive size, and became dominant."

"So these amphibians are actually an integral part of the story of how dinosaurs rose to power, believe it or not!" Brusatte added.

Fortunately, it looks like a wealth of new fossils from this captivating ecosystem may be recovered in the near future. The ancient lakebed where these specimens were discovered has hardly been explored at all, and Brusatte thinks it may have preserved hundreds of skeletons from the Metoposaurus's world.

"It looks like this was an ancient lake or pond that probably dried up, and because these amphibians need to be near the water to survive but have such pathetic limbs that they can't move easily on land, they probably were pretty much screwed," he said.

'We went back a few times and so far have excavated just a tiny portion of the bonebed, about four square meters," Brusatte continued. "We have already collected parts of several skeletons and hope to go back soon to keep digging."

Given what the lakebed has delivered so far, it's safe to assume some promising finds are in the works. After all, this is the geological epoch that gave us two-legged crocodiles and monster Metoposaurus salamanders. What will it serve up next?