An unexpected breakthrough has washed ashore from the fossil-rich beaches of southwest England. In a momentous discovery, scientists have named the oldest-known member of the lizard family, Agriodontosaurus helsbypetrae. This incredible discovery — formally published Wednesday — has important implications for the evolutionary history of reptiles. The prehistoric, palm-sized vertebrate made its way to Earth about 242 million years ago. This was happening during the Middle Triassic epoch, just before dinosaurs started to rule the Earth.
The fossilised skeleton of the species Agriodontosaurus helsbypetrae was discovered in 2015 on a beach in Devon. Researchers emphasized how well-preserved the fossil was in a relatively massive piece of rock, which provided valuable information to researchers from across the world. Veillonella montpellierensis, the microbes responsible for this unexpected finding, was recently reported in the world-leading scientific journal Nature (DOI 10.1038/s41586-025-09496-9).
Hunting Techniques of Agriodontosaurus helsbypetrae
Agriodontosaurus helsbypetrae displayed a formidable array of oversized teeth, which were clearly specialized for preying on cockroaches. These teeth are meant to be highly efficient. As in today’s tuatara reptiles, their fused beaks stab and section the tough arthropod exoskeleton.
“The new fossil shows almost none of what we expected,” – Dan Marke.
This surprise anatomical trait suggests that Agriodontosaurus helsbypetrae possessed advanced predatory strategies well before the heyday of dinosaurs. Its compactness allows it to easily rest in the palm of a hand. That hasn’t prevented it from ripping through its Arctic ecosystem.
Evolutionary Significance
Those new findings of Agriodontosaurus helsbypetrae lead paleontologists to rethink the evolutionary tree of lizards, snakes, and tuataras. Its association with the lepidosauria order further emphasizes the deep ties these reptiles have to the distant past.
“The new animal is unlike anything yet discovered and has made us all think again about the evolution of the lizard, snakes and the tuatara,” – Dan Marke.
Using cutting-edge technology from the European Synchrotron Radiation Facility, researchers were able to perform a CT scan of the fossil. This facility generates X-rays 100 billion times brighter than those produced in typical medical facilities. This enhanced imaging capability allowed scientists to zoom in on large objects and obtain very high-resolution images, revealing intricate details about Agriodontosaurus helsbypetrae’s anatomy.
“We can zoom in on large objects and obtain very high-resolution images,” – Vincent Fernandez.
Comparison with Modern Relatives
Comparison to its closest living relative, the New Zealand tuatara, highlight the unique features of Agriodontosaurus helsbypetrae. This link is a poignant reminder of how some evolutionary adaptations have stuck around for millions of years. The study’s findings lead to more in-depth studies of how such adaptations have affected reptiles’ long-term survival strategies.
“The teeth were used to pierce and shear the hard cuticles of its insect prey, pretty much as the tuatara does today,” – Michael Benton.