An extinct species that lived among the dinosaurs, discovered after 150 million years

Researchers from Smithsonian have discovered a new extinct species of reptile that inhabited North America during the Jurassic period.

The reptile is described by scientists as Opisthiamimus gregori and is named after Natural History Museum volunteer Joseph Gregor, who caught the scientists’ attention after spending hours scraping the bones from a block of stone.

The reptile lived alongside dinosaurs such as Stegosaurus and Allosaurus. Its closest living relative was found to be the tuatara, which inhabits New Zealand.

The tuatara looks like an iguana, but it’s not actually a lizard. They are actually rhynchocephalus, a species whose origins date back more than 200 million years.

“What’s important about the tuatara is that it represents this huge evolutionary story that we’re lucky enough to capture in what is probably its final act,” said Matthew Carrano, curator of Dinosauria at National Natural History Museum.

Tracing the history of the reptile

Posted in Journal of Systematic Paleontology, research says the reptile measured 16 inches from nose to tail and likely survived on a diet of mostly insects.

The extinct species was discovered through a number of specimens, including a well-preserved fossil skeleton excavated from an Allosaurus nest in Wyoming.

The creatures were found to be rhynchocephalic like the tuatara, an order that diverged from the lizards at least 230 million years ago. If studied further, this specimen could explain why the reptile was diverse and numerous during the Jurassic period, but is now an extinct species.

The fossil of the extinct reptile is almost complete except for the tail and part of the hind legs. Such a complete skeleton is rare for an extinct species like this because they have fragile bones that were either destroyed before they fossilized or eroded to the present day.

Therefore, scientists mainly study the reptile’s jaw and teeth. David DeMar, a research associate at the National Museum of Natural History, used high-resolution technology to take multiple X-ray images to create a three-dimensional representation of the extinct species.

The reconstructed three-dimensional skull provided researchers with a detailed image of the extinct reptile’s skull, which helped them discover what the creature might have eaten. Given its diminutive size, the shape of its teeth and skull, DeMar concluded that the reptile likely fed on insects, particularly harder-shelled prey such as beetles or water bugs.

The extinct species’ skull essentially looks like a miniature version of its only surviving relative, the tuatara, which is about five times as long.

“Such a complete specimen has tremendous potential for making comparisons with fossils collected in the future and for identifying or reclassifying specimens that are already sitting somewhere in a museum drawer,” DeMar said. “With the 3D models that we have, at some point we could also do studies that use software to look at the mechanics of the jaw of this creature.”

Further research is needed

During the Jurassic period, rhynchocephalans were found all over the world, varying in size and acting as fish hunters and plant eaters.

This evolutionary gap between lizards and rhynchocephals helps explain the tuatara’s strange characteristics, such as teeth fused to the jawbone, a unique chewing motion that slides the lower jaw back and forth like a saw blade, a lifespan of over 100 years, and a tolerance for po -cold climates.

However, scientists still do not understand why rhynchocephals began to disappear as snakes and lizards became more common around the world.

The fossil is kept by a museum collection, so scientists may discover why it is a nearly extinct species and the tuatara is all that remains of the rhynchocephalus, while lizards are now found all over the world.

“These animals may have gone extinct in part because of competition from the lizards, but also perhaps because of global climate change and changing habitats,” Carano said.

“It’s fascinating when you have the dominance of one group giving way to another group over evolutionary time, and we still need more evidence to explain exactly what happened, but fossils like this are how we’re going to piece it together .”