Lizard Fossil in Montana Reveals a New Dino-Era Species

The nearly complete skeleton offers scientists a rare glimpse into how lizards evolved 75 million years ago.

A famed Montana fossil site has yielded a new species of lizard that lived late in the dinosaur era, some 75 million years ago.

The new species, called Magnuviator ovimonsensis and unearthed at the fossil-rich "Egg Mountain" site in Montana, will help scientists better understand how lizards evolved during the days when dinosaurs roamed the Earth, say researchers who made the discovery. The team, from the University of Washington (UW), Montana State University and the Burke Museum of Natural History & Culture, published its findings on the new lizard in the journal Proceedings of the Royal Society B.

All told, two nearly complete fossil skeletons of the species were recovered. The samples were subjected to multiple rounds of CT scans – one to distinguish the skeletons from the rock that encased them, and others to fashion digital recreations of the skulls of the creatures.

Analysis of the ancient animal's anatomy told the scientists it was a new species, one that most closely resembled Cretaceous iguanians from far-off Mongolia and not other fossil lizards from the Americas. Magnuviator, then, was more like an evolutionary offshoot, or "stem," of iguanian lizards, they said - "at best" a distant relative of modern lizards such as chameleons and anoles.

"These ancient lineages are not the iguanian lizards which dominate parts of the Americas today, such as anoles and horned lizards," explained lead author David DeMar, of UW, in a statement. "So discoveries like Magnuviator give us a rare glimpse into the types of 'stem' lizards that were present before the extinction of the dinosaurs."

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The researchers named their find In honor of the famous location where it was discovered. Magnuviator ovimonsensis translates to "mighty traveler from Egg Mountain."

The world's first discovery of dinosaur embryos was made at Egg Mountain, and the first baby dinosaur fossils came from the site a well. Thought to have been dry and arid 75 million years ago, the site has also yielded wasp pupae cases and pollen grains from plants.

The researchers think, based on Magnuviator's teeth and the diet of some modern lizards, that the ancient lizard might have dined on such wasps at Egg Mountain, although they allow that it could have been eating other things, given its relatively large size of 14 inches long.

"Due to the significant metabolic requirements to digest plant material, only lizards above a certain body size can eat plants, and Magnuviator definitely falls within that size range," said DeMar.

The scientists think stem lineages like Magnuviator and its far-flung Mongolian brethren might have died out at the same time as non-avian dinosaurs, although the reasons why have yet to be uncovered.

Top Photo: An illustrated life reconstruction of Magnuviator ovimonsensis at the Egg Mountain site, as it may have appeared in the Cretaceous Period 75 million years ago. Magnuviator eats a wasp, and on the ground is a tooth from the bird-like dinosaur Troodon. The arid-adapted plant is based on fossil pollen found near Egg Mountain. Credit: Misaki Ouchida WATCH VIDEO: We Found Wild Chameleons in Florida