Researchers discover prehistoric extinct reptile that lived among dinosaurs

Smithsonian researchers have discovered a new extinct lizard-like reptile that belongs to the same ancient lineage as the tuatara extant in New Zealand. The new species, Opisthiamimus gregori, was published in the Journal of Systematic Palaeontology on September 15, local time. It lived with dinosaurs such as Stegosaurus and Allosaurus in the Jurassic North America about 150 million years ago. The discovery sheds light on Tutara, the last living member of a once diverse reptile group that was almost entirely replaced by lizards. Smithsonian researchers have discovered a new extinct lizard-like reptile that belongs to the same ancient lineage as the tuatara extant in New Zealand. The new species, Opisthiamimus gregori, was published in the Journal of Systematic Palaeontology on September 15, local time. It lived with dinosaurs such as Stegosaurus and Allosaurus in the Jurassic North America about 150 million years ago. In life, this prehistoric reptile was about 16 centimeters from nose to tail, and it could curl up in the palm of an adult. It probably survived by feeding on insects and other invertebrates. A team of scientists - including the National Museum of Natural History's Dinosaur Curator Matthew Carrano and Research Associate David DeMar Jr. and UCL and Natural History Museum London Science Associate Marc Jones - contributed to the study. Among them, Carrano said: "What's so important about the tuatara is that it represents this huge evolutionary story, and we're lucky to have caught it in what could be its finale. Although it looks like a A relatively simple lizard, but it embodies an entire evolutionary epic, dating back more than 200 million years." The find comes from a handful of specimens, one of which is a complete and well-preserved fossil skeleton from Wyoming A site centered on the Allosaurus lair in the Morrison Formation in the north of the state was excavated. Further investigation of the discovery may help shed light on why the animal's ancient reptilian order was strangled. While the tuatara looks a bit like a particularly stocky iguana, the tuatara and its newfound relative aren't actually lizards at all. They were actually rhynchocephalians -- a species that diverged from lizards at least 230 million years ago, Carrano said. During the heyday of the Jurassic period, rhynchocephalians could be found almost everywhere in the world, large and small. Their ecological roles range from aquatic fish hunters to hulking plant eaters. But for reasons not yet fully understood, rhynchocephalians all but disappeared as lizards and snakes became more common and diverse reptiles around the globe. This evolutionary gap between lizards and rhynchocephalians helps explain the strange features of tuatara. These features include a lifespan of over 100 years, fusion of teeth with jawbone, unique chewing action, jaw-sliding back and forth like a saw blade and tolerance to cold climates. Following a formal description of Opisthiamimus gregori, Carrano said the fossil has been included in the museum's collection and it will remain available for future research. Maybe one day, it will help scientists figure out why tuatara are the only rhynchocephalians and why lizards are now found all over the globe. "Part of the disappearance of these animals may be due to competition from lizards, but it may also be due to changes in global climate and habitat changes. When you have the dominance of one group giving way to another over the course of evolution, this It's fascinating, and we still need more evidence to explain what's going on, but a fossil like this is how we're going to put it together," Carrano said. The new species is named after museum volunteer Joseph Gregor. The volunteer is understood to have spent hundreds of hours laboriously scraping and chipping bones from a stone that caught the attention of museum fossil preparer Pete Kroehler as early as 2010. "Pete is the kind of guy who has an x-ray vision for this kind of thing, he noticed two tiny blobs of bone on the side of this fossil and marked to take it back, but didn't know what was in there. Facts Proof, he hit the jackpot," Carrano said. The fossil is almost completely intact - except for the tail and part of the hind legs. Such complete skeletons are very rare for small prehistoric creatures like this, Carrano said, because their fragile bones were often damaged before fossils or when they emerged from eroded rock formations today. Thus, paleontologists mostly know about rhynchocephalians from small fragments of their jaws and teeth. After Kroehler, Gregor and others released as many tiny fossils as possible from the rock, the team led by DeMar set out to scan the fossils with high-resolution computed tomography. This is a method of creating a three-dimensional image of a specimen using multiple X-ray images at different angles. The research team used three separate CT scans -- including one at the National Museum of Natural History -- to capture everything they could possibly know about the fossil. Once the fossil's skeleton was digitized to less than a millimeter, DeMar began to reassemble the skull's digitized skeleton. Some of the bones were crushed, out of place, or missing on one side, so the researchers used software to eventually create a nearly complete 3D reconstruction. This reconstructed 3D skull is now giving scientists an unprecedented look at what the head of this Jurassic-era reptile looked like. Given its tiny size, tooth shape and hard skull, Opisthiamimus likely eats insects, DeMar said. Plus, he added, hard-shelled prey, such as beetles or water bugs, may also be on the menu. Broadly speaking, the new species looks a bit like a scaled-down version of its only surviving relative. "Such a complete specimen has enormous potential to be compared with fossils collected in the future, as well as to identify or reclassify specimens already in museum drawers. With the 3D models we have, at some point , we can also do some research using software to look at the jaw mechanics of this animal."