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Prehistoric Reptiles That Lived Amongst Dinosaurs Found by Smithsonian Researchers

An inventive interpretation of a not too long ago extinct lizard-like reptile from New Zealand’s historic and residing tuatara. The most recent discovery Allow us to pray to Gregory eats an extinct aquatic insect (Morrisonnepa jurassica), within the background is a predatory dinosaur Allosaurus jimmadseni defending his nest. The scene is a river flood in Late Jurassic Wyoming, about 150 million years in the past. A crew of scientists describes the brand new species, which lived in Jurassic North America about 150 million years in the past alongside dinosaurs akin to Stegosaurus and Allosaurus, in a paper printed as we speak in within the Journal of Systematic Palaeontology. In life, this prehistoric reptile measures about 16 centimeters (six inches) from nostril to tail and suits within the palm of an grownup’s hand. The invention relies on a number of specimens together with a really full and well-preserved skeleton excavated close to an Allosaurus nest in northern Wyoming’s Morrison Formation. Credit score: Julius Csotonyi for the Smithsonian Establishment

Discovery discovers the story of the tuatara, the final member of a various group of reptiles which have been virtually fully changed by lizards.

A brand new species of lizard-like reptile from New Zealand’s historic lineage and residing tuatara has been found by Smithsonian researchers. New species Allow us to pray to Gregorywas beforehand inhabited[{” attribute=””>Jurassic North America about 150 million years ago alongside dinosaurs like Stegosaurus and Allosaurus, is described in a paper published on September 15, 2022, in the Journal of Systematic Palaeontology. In life, this prehistoric reptile would have been about 16 centimeters (about 6 inches) from nose to tail—and would fit curled up in the palm of an adult human hand. It likely survived on a diet of insects and other invertebrates.

A team of scientists, including the National Museum of Natural History’s curator of Dinosauria Matthew Carrano and research associate David DeMar Jr. as well as University College London and Natural History Museum, London scientific associate Marc Jones, contributed to the research.

“What’s important about the tuatara is that it represents this enormous evolutionary story that we are lucky enough to catch in what is likely its closing act,” Carrano said. “Even though it looks like a relatively simple lizard, it embodies an entire evolutionary epic going back more than 200 million years.”

Fossil Skeleton of the New Lizard-Like Reptile Opisthiamimus Gregori

Fossil skeleton of the new lizard-like reptile Opisthiamimus gregori. The fossil was discovered in the Morrison Formation of the Bighorn Basin, north-central Wyoming, and dates to the Late Jurassic Period, approximately 150 million years ago. Researchers named the new species after Smithsonian’s National Museum of Natural History volunteer Joseph Gregor who 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. The fossil has been added to the museum’s collections where it will remain available for future study. A team of scientists describes the new species, which once lived alongside dinosaurs like Stegosaurus and Allosaurus, in a paper published today in the Journal of Systematic Palaeontology. In life, this prehistoric reptile would have been about 16 centimeters (about 6 inches) from nose to tail—and would fit curled up in the palm of an adult human hand—and likely survived on a diet of insects and other invertebrates. Credit: David DeMar for the Smithsonian Institution

The discovery comes from a handful of specimens, one of which was an incredibly complete and well-preserved fossil skeleton excavated from a site centered around an Allosaurus nest in northern Wyoming’s Morrison Formation. Further investigation of the find could help reveal why this animal’s ancient order of reptiles was winnowed down from being diverse and numerous in the Jurassic to only New Zealand’s tuatara surviving today.

Although the tuatara looks a bit like a particularly stout iguana, the tuatara and its newly discovered relative are in fact not lizards at all. They are actually rhynchocephalians, an order that diverged from lizards at least 230 million years ago, Carrano said.


The analysis crew scanned the fossil with computed tomography (CT), a way that makes use of a number of X-ray pictures from completely different angles to create a 3D picture of the specimen. The crew used three separate CT scan websites, together with one on the Smithsonian Nationwide Museum, to seize all the pieces they may concerning the fossil. After digitizing the bones of the fossil, the crew got down to piece collectively the digitized bones of the cranium, a few of which have been damaged, misplaced or lacking on one aspect, utilizing laptop to create a virtually full 3D construction. A crew of scientists describes a brand new species of Opisthiamimus gregori, which lived alongside dinosaurs like Stegosaurus and Allosaurus, in a paper printed as we speak within the Journal of Systematic Palaeontology. In life, this primitive reptile measures about 16 centimeters (about 6 inches) from nostril to tail—and may match within the palm of an grownup’s hand—and survive from being eaten by bugs and different bugs. Credit score: D. DeMar

At their top in the course of the Jurassic interval, rhynchocephalians of all shapes and sizes have been discovered virtually all over the place on the planet. They crammed ecological roles from aquatic fishermen to plant eaters. However for causes which are nonetheless not totally understood, rhynchocephalians disappeared fully as lizards and snakes advanced into extra widespread and various reptiles all over the world.

The break up between lizards and rhynchocephalians explains the variations in vertebrates. These embody a 100-year lifespan, jaw-jointed tooth, a novel chewing movement that causes the decrease jaw to slip backwards and forwards like a noticed blade, and a tolerance for chilly climate.

Opisthiamimus gregori Skull

3D reconstruction of the cranium of Allow us to pray to Gregory, a brand new extinct lizard-like reptile from the Late Jurassic of Wyoming, US Particular person bones are color-coded. Credit score: D. DeMar

Comply with up O. gregoriCarrano’s formal description said that fossils added to the museum’s collections can be obtainable for future examine. Possibly in the future it can assist scientists to grasp what’s left of rhynchocephalians, however lizards are discovered all around the world.

“These animals could have turn out to be extinct partly due to competitors from lizards but in addition due to international local weather change and altering habitats,” Carrano stated. “It is fascinating that you’ve got the facility of 1 group giving option to one other group in evolutionary time, and we nonetheless want extra proof to elucidate what occurred, however such instincts as the best way to unite.”

The brand new species was named after Joseph Gregor, a museum volunteer who spent tons of of hours digging and dissecting the bones from a block of stone that attracted the eye of museum curator Pete Kroehler. the yr 2010.

“Pete’s a type of guys who has form of X-ray imaginative and prescient for this sort of factor,” Carrano stated. “He noticed two small bones subsequent to this block and determined to carry them again with out figuring out precisely what they contained. Because it turned out, he hit the jackpot.”

Opisthiamimus Gregori Skeleton

{Photograph} (prime) and schematic drawing (backside) of the cranium and skeleton of Allow us to pray to Gregorya brand new extinct species of lizard-like reptile from the Late Jurassic of Wyoming, US Credit score: D. DeMar (photograph, prime), James Morrison (photograph, backside).

The fossil is nearly full, apart from the tail and elements of the hind legs. Excellent skeletons like this are uncommon for prehistoric creatures like this, Carrano stated, as a result of their fragile bones typically broke earlier than they fossilized or emerged from the rock. corridor lately. Because of this, rhynchocephalians are principally recognized to paleontologists from small fragments of their jaws and tooth.

After Kroehler, Gregor, and others simply disentangled small fossils from the rock, the crew, led by DeMar, got down to scan the fossil with high-resolution computed tomography (CT ). This can be a method that makes use of a number of X-ray pictures from completely different angles to create a 3D picture of the specimen. The analysis crew used three separate CT scan websites, together with one on the Nationwide Museum of Artwork, to seize all the pieces they may concerning the fossil.

After digitizing the bones of the breast to the[{” attribute=””>accuracy smaller than a millimeter, DeMar set about reassembling the digitized bones of the skull. Some of them were crushed, out of place, or missing on one side, so software was used to eventually create a nearly complete 3D reconstruction. This reconstructed 3D skull now provides scientists with an unprecedented look at this Jurassic-age reptile’s head.

Given Opisthiamimus’s diminutive size, tooth shape, and rigid skull, it likely ate insects, said DeMar, adding that prey with harder shells such as beetles or water bugs might have also been on the menu. Broadly speaking, the new species looks quite a bit like a miniaturized version of its only surviving relative (tuataras are about five times longer).

“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,” DeMar said. “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.”

Reference: “A nearly complete skeleton of a new eusphenodontian from the Upper Jurassic Morrison Formation, Wyoming, USA, provides insight into the evolution and diversity of Rhynchocephalia (Reptilia: Lepidosauria)” 15 September 2022, Journal of Systematic Palaeontology.
DOI: 10.1080/14772019.2022.2093139

Funding and support for this research were provided by the Smithsonian and the Australian Research Council.

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