New Species of Ancient Reptile With 'Unusual' Jaws Discovered

A remarkable reptile-like creature with an unusual jaw that lived more than 200 million years ago has been described as a new species. Evidence of the species, Threordatoth chasmatos, was unearthed from a former quarry in Cromhall, South West England—a site renowned for its abundant fossil remains dated to the Triassic period (roughly 252-201 million years ago). Over the past few decades, the site has yielded fossils of gliding reptiles, dinosaur relatives and even one of the earliest known lizards. The latest discovery, detailed in the journal Papers in Palaeontology, reveals one of the last surviving procolophonids, an extinct group of lizard-like animals that thrived during the Triassic. While they would have looked like lizards, procolophonids are not closely related to them. Procolophonids are classed as parareptiles. These extinct creatures are similar to what we call reptiles today, but they represent a distinct lineage that diverged from the common ancestor of contemporary reptiles and birds.

For the latest study, paleontologists examined a set of fossils from Cromhall that are being kept in collections by various institutions. The fossils had never been investigated in detail before. Even though the remains only consisted of incomplete jaw bones, the researchers soon realized they represented a previously unknown species due to several distinctive characteristics. "These specimens had a lot of unusual characteristics," study author Marc Jones, curator of fossil reptiles with the Natural History Museum in London, said in a press release. "The front of the jaw, for example, isn't fused together, and there's no obvious site where they would connect together. Instead, we think that the two halves of the jaw were probably connected by ligaments." "If this was the case, the jaw would have been somewhat flexible. It may have aided tooth-on-tooth contact during chewing and provided some shock-absorption potential, preventing forces being transferred between the two sides of the jaw." However, the teeth of Threordatoth, in particular, enabled researchers to help distinguish it from other related species. These teeth have three points, a feature not seen in any of its relatives. Previous research has indicated that as procolophonids evolved over the course of the Triassic, they experienced a reduction in the number of teeth—a possible sign that they were adapting to more specialized lifestyles. Procolophonid teeth are relatively complex, potentially allowing the animals to process a range of foods, including plants and insects. "As time passes, we see that most procolophonids develop teeth with two points and reduce their tooth count," study lead author Luke Meade, affiliated with the University of Birmingham, said. "It's thought this might have allowed these animals to eat tougher diets, perhaps as they became more herbivorous." "Threordatoth took the tooth reduction trend further than any other procolophonid in the Late Triassic. It has just four teeth on either side of its jaw." The newly described species would probably have looked similar to modern horned lizards, with bony spikes on its head and potentially some bony armor on its body. "I like to imagine them scampering around the sinkholes and fissures of southwest England in the Late Triassic, looking for plants and bugs to eat while avoiding the early relatives of dinosaurs," Meade said. Because procolophonid bones are typically quite small, in many cases, they would have been damaged or destroyed before the process of fossilization even began. This generally means researchers have to rely on teeth and jawbones—which are more frequently preserved—to learn about these animals. As a result, there is still a large gap in our knowledge of these prehistoric creatures. "By continuing to investigate sites like Cromhall, we can hopefully answer some of our outstanding questions," Jones said. Do you have an animal or nature story to share with Newsweek? Do you have a question about paleontology? Let us know via science@newsweek.com.

Reference

Meade, L. E., Butler, R. J., Jones, M. E. H., & Fraser, N. C. (2024). A new procolophonid with complex dentition from the Late Triassic of southwest England. Papers in Palaeontology, 10(6). https://doi.org/10.1002/spp2.1605