The discovery of a tiny fossilized skeleton in a quarry near Bristol has rewritten the evolutionary timeline of modern lizards. Unearthed from Triassic-aged rocks and estimated to be at least 205 million years old, this specimen is now recognized as the oldest modern-type lizard ever recorded. The fossil has been identified as a member of the lizard-snake group known as Squamata, shifting the group’s origins back by an astounding 35 million years.
The fossil, named Cryptovaranoides microlanius, was first described by a team from the University of Bristol, including Dr. David Whiteside, Dr. Sofia Chambi-Trowell, and Professor Mike Benton. The name translates to “hidden lizard, small butcher,” reflecting both its subtle discovery and the sharp teeth it likely used to tear prey. Their research, initially published in 2022, highlighted numerous anatomical features that placed the fossil firmly within Squamata, specifically linking it to modern anguimorphs like monitor lizards and slow worms.
However, this groundbreaking find soon faced controversy. A rival study in 2023 challenged the classification, arguing that Cryptovaranoides was not a lizard at all but an archosauromorph—a group more closely related to crocodiles and dinosaurs. The Bristol team, surprised by this claim, revisited their original analysis and undertook a detailed re-examination of the fossil, including its CT scan data, to address the criticisms.
Dr. Chambi-Trowell explained how the team re-evaluated every aspect of the fossil, using both physical examination and advanced imaging techniques. The CT scans, which revealed intricate details hidden within the rock, were instrumental in confirming the fossil’s true nature. “We found that most of the concerns raised in the rival paper were incorrect,” she noted.
The reanalysis confirmed that all key anatomical features—skull structure, jaw shape, tooth arrangement, and limb bones—aligned with characteristics of modern lizards, not archosauromorphs. To further validate their findings, the researchers conducted an exhaustive phylogenetic analysis. This involved coding hundreds of anatomical traits for Cryptovaranoides and comparing them to a wide range of modern and fossil lizards as well as archosauromorphs. The results consistently placed the fossil within Squamata.
The team’s rebuttal, published in Royal Society Open Science, provided an even more comprehensive account of the fossil’s anatomy. “We included additional photographs, 3D scans, and detailed comparisons, so others could verify our conclusions,” said Professor Benton. Their analysis upheld the original classification, firmly establishing Cryptovaranoides as the world’s oldest modern-type lizard.
This discovery has profound implications for our understanding of reptile evolution. By pushing the origins of Squamata back to the late Triassic, it fills a significant gap in the fossil record and provides new insights into the early diversification of reptiles. It also highlights the importance of meticulous re-evaluation in paleontology, where new techniques can reinforce or challenge longstanding conclusions.
Dr. Whiteside emphasized the significance of the find, stating, “Our work not only confirms the identity of Cryptovaranoides but also reshapes our understanding of how modern reptiles evolved. This tiny fossil has a big story to tell about the origins of lizards and their incredible journey through time.”
The Cryptovaranoides microlanius fossil now stands as a critical piece of evidence in the study of reptilian ancestry, offering a clearer picture of life over 200 million years ago and underscoring the complex evolutionary pathways that led to the diverse species we see today.
Source: University of Bristol