A fossil that reshapes the timeline of modern lizard evolution has been officially confirmed as the oldest known member of the lizard family. The specimen, discovered in Triassic-era rocks near Bristol, is at least 205 million years old, making it the oldest modern-type lizard on record.
This confirmation comes after the initial findings, published by the University of Bristol team, were questioned by a separate group of researchers. However, fresh analysis published today in Royal Society Open Science reaffirms the fossil’s connection to modern anguimorphs, a group that includes anguids and monitors. The research shifts the origins of the Squamata order—encompassing lizards and snakes—back by 35 million years.
In the original study, Dr. David Whiteside, Dr. Sofia Chambi-Trowell, and Professor Mike Benton identified the creature as Cryptovaranoides microlanius, meaning “hidden lizard, small butcher.” This name reflects both its lizard classification and its sharp teeth, likely used to slice through prey. Through detailed examination of its skull and skeleton, the team placed the creature firmly within the Squamata clade, close to the Anguimorpha suborder.
“We expected our paper to spark debate,” Dr. Whiteside said. “However, we were confident that we had examined every possible feature and made thorough comparisons.”
The team was taken aback when, in 2023, another research group suggested that Cryptovaranoides might not be a lizard at all, but rather an archosauromorph—closely related to crocodiles and dinosaurs. In response, the Bristol team revisited their findings, utilizing detailed CT scans and additional examination of the fossil.
“We had access to incredible X-ray images, which allowed us to recheck every aspect of the fossil,” Dr. Chambi-Trowell explained. “Most of the concerns raised in the competing paper were unfounded.”
Professor Benton emphasized, “The skull, teeth, jaws, and limb bones all point to Cryptovaranoides being a lizard, not an archosauromorph.”
The team’s new paper addresses each criticism raised, providing updated photographs and 3D scans of the specimen to allow others to verify the details. Additionally, the team conducted a phylogenetic analysis, comparing hundreds of anatomical traits from Cryptovaranoides and other lizards and archosauromorphs. The results consistently supported their original conclusion that the fossil represents the world’s oldest modern-type lizard.
“This extensive testing further confirmed our findings,” Dr. Whiteside concluded. “Cryptovaranoides is, without doubt, the earliest known example of a modern lizard.”
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