Newly discovered fossils of lizard-like animal are the oldest ever found

An extinct species has revealed new twists within the story of lizards and their kin.

Discovered close to the city of Sidmouth in Devon, Agriodontosaurus helsbypetrae was an insect-eating reptile that lived greater than 241 million years in the past through the Middle Triassic. It’s a part of a reptile group often known as the lepidosaurs, which accommodates snakes, lizards and an animal often known as the tuatara.

Today, there are over 12,000 species of lepidosaurs, making them essentially the most species-rich teams of land vertebrates. But it’s laborious to know the place they got here from as the delicate bones of their early ancestors are susceptible to being broken or destroyed.

Agriodontosaurus is at present the oldest recognized member of the group, being as as much as seven million years older than every other recognized lepidosaur. But the fossil has shocked scientists as a result of it it’s lacking a number of the key options early lepidosaurs had been anticipated to have, comparable to tooth on the roof of its mouth.

Dan Marke, who led the analysis into the reptile as a part of his Masters diploma on the University of Bristol, says that Agriodontosaurus “is unlike anything yet discovered and has made us all think again about the evolution of the lizard, snakes and the tuatara.”

“This specimen not only provides important information about the ancestral skull of all lepidosaurs but also builds on growing knowledge of the tuatara. While often called a ‘living fossil’, this animal belongs to a once-diverse order of ancient reptiles with a rich evolutionary history.”

The findings of the research had been revealed within the journal Nature.

How did Agriodontosaurus reside?

As properly as being the oldest recognized lepidosaur, Agriodontosaurus can also be the earliest recognized rhyncocephalian. This is a particular group of lizard-like animals of which the tuatara is the one surviving member.

The tuatara makes use of its tooth to assist it pierce the exoskeletons of bugs and shear them aside, and it’s possible that Agriodontosaurus did one thing comparable. The fossilised tooth of the traditional animal are a lot bigger than these of its kin and gave the species its identify, as Agriodontosaurus means ‘fierce toothed lizard’ in historic Greek.

The workforce imagine that it most likely consumed massive bugs comparable to cockroaches, crickets and grasshoppers. This is a way of life that hasn’t been present in every other Triassic lepidosaur earlier than. Agriodontosaurus’s massive eye sockets counsel it might have been good at discovering prey, whereas it most likely had good listening to to help in looking.

Once it caught the invertebrates, Agriodontosaurus would have held them tight in its mouth because of its robust jaw muscle tissues and tongue, after which used it tooth to chop the bugs up.

During the Middle Triassic ecosystems had been altering, and the researchers assume that Agriodontosaurus a part of an evolutionary burst of reptiles that was taking up from mammal-like animals often known as the synapsids. By the top of the Triassic, the ancestors of recent lizards and snakes can be taking their first steps in the direction of international dominance alongside the dinosaurs.

Lepidosaur evolution has surprises in retailer

The evolutionary journey taken by the lepidosaurs, nonetheless, wasn’t fairly as anticipated. Dr David Whiteside, one in every of our scientific associates who co-authored the analysis, stated that detailed scans of the fossil revealed Agriodontosaurus’ uncommon traits.

“In modern palaeontological studies we often X-ray scan the fossils,” David says. “But the exceptional resolution and quality of scans from synchrotron X-ray sources show us all the fine details and save any risk of damage.”

“An earlier Masters student, Thitiwoot Sethapanichsakul, had worked on the regular scans and found fantastic detail, but Agriodontosaurus is so tiny – the skull is only 1.5 cm long, and we could barely see the teeth. So, we were so grateful to be able to make synchrotron CT scans to get even finer resolution.”

It had been thought that the primary lepidosaurs would have had a number of the key traits of recent snakes and lizards which these animals had inherited. These embody {a partially} hinged cranium, tooth on the roof of the mouth and a niche between cranium bones often known as an open temporal bar.

This permits them to maneuver completely different elements of the cranium independently to stretch out their jaws and permits them to swallow a lot bigger prey. However, Agriodontosaurus defied expectations, having simply one in every of these three options.

“The new fossil shows almost none of the characters we expected,” stated Dan. “It has no teeth on its palate and no sign of any hinging, just an open temporal bar.”

It means that these traits could have appeared a number of instances within the historical past of those animals as they advanced, moderately than being inherited from a typical ancestor. This might have helped give lepidosaurs an edge as they turned such a recognisable a part of life on Earth.