Scientists unearth extinct reptile that roamed Earth when the dinosaurs did

By Mark Waghorn via SWNS

An extinct reptile that lived among the dinosaurs 150 million years ago has been unearthed in the badlands of Wyoming.

The tiny creature sheds light on New Zealand's tuatara, the last living member of a group that has almost entirely been supplanted by lizards.

About six inches long from nose to tail, the "miniature version" would fit curled up in the palm of your hand. It snacked on insects - including beetles and primitive water bugs.

Named Opisthiamimus gregori, its fossilized remains were entombed in rocks from a river floodplain dating back to the Late Jurassic.

They were near a nest belonging to an Allosaurus - a horned and crested beast that ripped animals to shreds. Armoured Stegosaurus also inhabited the area.

Lead author Dr. Matthew Carrano, of the Smithsonian Institution, Washington DC, said: "What's important about the tuatara is it represents this enormous evolutionary story that we are lucky enough to catch in what is likely its closing act.

"Even though it looks like a relatively simple lizard, it embodies an entire evolutionary epic going back more than 200 million years."

The tuatara is five times as big as Opisthiamimus - resembles a fat iguana. Like its newly discovered relative, they are not lizards but rhynchocephalians.

Once found across the world, they had diverged at least 230 million years ago. They ranged from large to small and from aquatic fish hunters to bulky plant munchers.

It is a mystery why they all but disappeared as lizards and snakes replaced them as the common reptiles across the globe.

The tuatara's evolution has fascinated evolutionary experts for decades. Odd features include teeth fused to the jaw bone.

It also has a unique chewing motion that slides the lower jaw back and forth like a saw blade, a 100 year plus lifespan - and a tolerance for colder climates.

Opisthiamimus has been added to the Smithsonian museum's collections where it will remain available for future study.

It may help researchers figure out why the tuatara is all that remains of the rhynchocephalians, while lizards have spread round the planet.

Dr. Carrano said: "These animals may have disappeared partly because of competition from lizards but perhaps also due to global shifts in climate and changing habitats.

"It is 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 one are how we will put it together."

The researchers named the new species after museum volunteer Joseph Gregor.

He spent hundreds of hours meticulously scraping and chiseling the bones from a block of stone that first caught museum fossil preparator Pete Kroehler's eye back in 2010.

Dr. Carrano said: "Pete is one of those people who has a kind of X-ray vision for this sort of thing.

"He noticed two tiny specks of bone on the side of this block and marked it to be brought back with no real idea what was in it. As it turns out, he hit the jackpot."

The fossil is almost entirely complete, with the exception of the tail and parts of the hind legs. Its skeleton is rare for small prehistoric creatures.

Their frail bones were often destroyed either before they fossilized or as they emerge from an eroding rock formation in the present day.

As a result, rhynchocephalians are mostly known to paleontologists from small fragments of their jaws and teeth.

State-of-the-art scanning techniques enabled the US team to create a 3D representation of the specimen.

Once the fossil's bones had been digitally rendered with an accuracy smaller than a millimeter, they were reassembled - despite being crushed, out of place or missing.

Software eventually provided them with an unprecedented look inside the Jurassic-age reptile's head.

Co-author David DeMar, a research associate, added: "Such a complete specimen has huge potential for making comparisons with fossils collected in the future and for identifying or reclassifying specimens already sitting in a museum drawer somewhere.

"With the 3D models we have, at some point, we could also do studies that use software to look at this critter’s jaw mechanics."

Opisthiamimus is described in the Journal of Systematic Palaeontology.