Ancient Reptile with Unique Teeth Found in Gloucestershire

A fossil hotspot in southern England has revealed another of its secrets. The former quarry located in Cromhall, South Gloucestershire, is renowned as a rich source of Triassic wildlife. Gliding reptiles, dinosaur relatives and even one of the earliest known lizards have all been found at the site over the past few decades. Now, scientists have described a new species of procolophonid reptile notable for its unusual dental apparatus and jaw mechanics. Their results are published in Papers in Palaeontology.

The remains of Threordatoth chasmatos, some of which are now cared for as part of the Natural History Museum collection, were recovered from ancient fissure fills, often described as ‘time capsules’ which had preserved fragments of skulls and jaws, offering insight into the anatomy of Threordatoth. The discovery offers a glimpse into the Carnian Norian age of the Late Triassic, roughly 220–210 million years ago allowing the researchers to reconstruct ecosystems from a period when early dinosaurs were emerging as dominant land animals.

"This small reptile’s teeth and jaw show features we’ve never seen before in its group," said lead author Dr Luke Meade, fellow at the University of Birmingham. "It likely fed in a way that distinguished it from its closest relatives, which opens up new questions about how these animals were interacting with their environment during the Late Triassic period."

The teeth of Threordatoth chasmatos set it apart from other procolophonids, a group of extinct, small-bodied reptiles. Its upper jaw features tricuspid teeth each with three distinct points—while the lower jaw bears compressed monocuspid teeth with an unusual edentulous (toothless) tip. These adaptations may have facilitated a distinct method of food processing.

"Inferring the interplay between the upper and lower teeth is fascinating, there are several aspects of the tooth shape that resemble those of mammals," explained Dr Marc Jones, Fossil reptiles Curator at Natural History Museum London. 

"The lower jaws were not fused at the chin, instead the connection was held with soft-tissue and likely flexible. This flexibility might have allowed the lower jaws to meet in a way that would help chewing food. This feature isn’t seen in closely related species and might indicate a specialized diet or feeding strategy."

The Late Triassic was a time of dramatic environmental change, as the supercontinent Pangaea began to break apart. The peculiar dental adaptations of Threordatoth chasmatos suggest it may have been exploiting a unique ecological niche in a changing climate, feeding on plants, insects, or other small prey that required specialized oral food processing.

Dr Jones adds, "Threordatoth chasmatos lived at a time when Solar irradiance was significantly lower than today but atmospheric CO2 was significantly greater. Overall, it was hotter, average global sea level was higher, and there were extreme rainfall events. Therefore, Threordatoth chasmatos and the community in which it lived could potentially provide perspectives for todays’ threatened ecosystems and the planetary emergency we face."

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