A fossil specimen, tucked away in a storeroom, that radically redefines our understanding of modern lizards’ evolutionary timeline has been definitively validated. The minuscule skeleton was originally found in a quarry near Bristol in Triassic-era rocks and is estimated to be at least 205 million years old, making it the oldest identified modern-type lizard.
The University of Bristol research team’s findings were recently challenged. However, a fresh analysis, released today in the Royal Society Open Science, confirms that the fossil is indeed a relative of contemporary anguimorphs, such as anguids and monitors. This discovery pushes back the origin of the entire lizard-snake group, known as Squamata, by an impressive 35 million years.
In the initial research, Dr David Whiteside, Dr Sofia Chambi-Trowell, and Professor Mike Benton named the diminutive creature ‘Cryptovaranoides microlanius,’ which translates to ‘hidden lizard, small butcher.’ This was in reference to its classification as a lizard and its pointed teeth, likely used for tearing apart prey. The Bristol team identified several anatomical characteristics in the skull and skeleton, placing it firmly within the Squamata group, and even close to Anguimorpha.
“We anticipated controversy surrounding our paper,” Dr Whiteside admitted. “However, we were confident that we had scrutinized every conceivable feature and made thorough comparisons.”
Professor Benton added, “We were therefore taken aback when another academic team suggested in 2023 that Cryptovaranoides was not a lizard or even a relative, but actually an archosauromorph, more akin to crocodiles and dinosaurs.”
In response to the challenge, the Bristol team revisited their original research and the counterarguments raised, examining all the data, including the original fossil and detailed X-ray scans. “The CT scans and further access to the fossil allowed us to address all their claims,” said Dr Chambi-Trowell. “We found most of the objections raised were unfounded.”
Professor Benton affirmed, “Every detail of the skull, jaws, teeth, and limbs verifies that Cryptovaranoides is a lizard, not an archosauromorph. In our new paper, we address every criticism in detail and provide more images and 3D scans of the specimen for public scrutiny.”
Finally, Dr Whiteside said, “The conclusions had to be corroborated by a phylogenetic analysis, where we coded hundreds of anatomical features in Cryptovaranoides and other modern and fossil lizards, as well as various archosauromorphs. We performed the analysis repeatedly, and it repeatedly confirmed our original finding: the tiny Bristol reptile is indeed the world’s oldest known modern-type lizard.”
