Oldest Known Lizard Ancestor Discovered in England

A tuatara lizard, which shows similarities with the recently recovered ancestor species. Credit: Stewart Nimmo / Wikimedia Commons / CC BY-SA 4.0

Scientists person identified the oldest known lizard ancestor, a fossil recovered connected a formation successful southwest England that dates backmost 242 cardinal years.

The small reptile, nary larger than a quality hand, lived successful the Middle Triassic period, conscionable earlier dinosaurs appeared, and relied connected oversized teeth to provender connected insects specified arsenic cockroaches.

The skeleton was discovered successful 2015 astatine a fossil-rich tract successful Devon and is present recognized arsenic the earliest subordinate of the reptile radical lepidosauria, which includes lizards, snakes, and the tuatara of New Zealand. Researchers spent years studying the remains earlier publishing their findings Wednesday successful the journal Nature.

Dan Marke of the University of Bristol, the study’s pb author, said the carnal challenges long-standing assumptions astir reptile evolution. According to him, the fossil lacked galore features typically expected successful aboriginal lepidosaurs, prompting scientists to reconsider however lizards, snakes, and tuataras developed.

Ancient features that defy expectations

Unlike modern lizards and snakes, which person a partially hinged skull and further teeth connected the extortion of the mouth, this aboriginal ancestor had neither.

Read astir the oldest known lepidosaur: Agriodontosaurus helsbypetrae.

"A tiny, snaggletoothed carnal that lived and died 241 cardinal years agone successful what is present the coastline of southwestern England belonged to a radical that gave emergence to a stupendously divers smattering of… pic.twitter.com/yQ0eWBiKv0

— Manuela Casasoli (@manuelacasasoli) September 13, 2025

Researchers noted its astir striking diagnostic was its unusually ample teeth compared with adjacent relatives. Another distinctive trait was a bony that stretched from the feature to the jaw, a diagnostic different seen lone successful the tuatara, sometimes called a living fossil.

Study co-author Michael Benton, besides from the University of Bristol, explained that the reptile apt utilized its salient teeth to pierce and shear the pugnacious shells of insects, overmuch arsenic the tuatara does today.

The fossil was hard to survey due to the fact that of its size. The skull measured lone 1.5 centimeters, oregon astir 0.6 inches, and was embedded successful a ample artifact of rock. To analyse it, British researchers relied connected precocious imaging astatine the European Synchrotron Radiation Facility successful France.

Technology and naming of the fossil

Vincent Fernandez, a paleontologist astatine the facility, said the synchrotron worked similar a almighty microscope, producing X-rays billions of times brighter than infirmary machines. This allowed the squad to seizure highly elaborate images of the tiny specimen.

The researchers named the reptile Agriodontosaurus helsbypetrae, aft the Helsby Sandstone Formation wherever it was found.

Its find provides scientists with a clearer presumption of aboriginal reptile evolution and offers uncommon penetration into the origins of a radical that would aboriginal diversify into thousands of taxon crossed the world.