A recent study published in Royal Society Open Science confirmed that the 205-million-year-old fossil named Cryptovaranoides Microlanius is the oldest known modern lizard, reshaping the timeline of reptile evolution. The findings push back the origins of the lizard-snake group called Squamata by 35 million years to at least 205 million years ago, according to Phys.org.
The fossil was unearthed from Triassic-aged rocks in a quarry near Bristol in the United Kingdom, as reported by Science Daily. The miniature skeleton sparked extensive discussion among scientists due to its unique characteristics and well-preserved state.
Since the initial study conducted by Dr. David Whiteside and published in 2022 in Science Advances, scientists have debated the identity of the specimen. Some parties questioned the findings, suggesting that Cryptovaranoides was not a lizard or its relative but closer to the group archosauromorph, which includes crocodiles and dinosaurs.
The University of Bristol team, led by Dr. Whiteside, responded to the criticism with further analysis. "We ran the analysis time after time, and it gave our original result, that the little Bristol reptile is indeed the world's oldest modern-type lizard," Dr. Whiteside confirmed.
Professor Mike Benton, also part of the research team, addressed the controversy. "We were therefore surprised, perhaps even shocked, that in 2023 another team of academics suggested that Cryptovaranoides was not a lizard or even a lizard relative, but in fact an archosauromorph, more closely related to crocodilians and dinosaurs," he said.
The team emphasized the importance of thorough examination and accurate interpretation of the fossil. "In our new paper, we provide great detail of every criticism made and we provide more photographs of the specimen and 3D images from the scans, so everyone can check the details," Professor Benton said.
The fossil has been preserved in remarkable detail, enhancing the importance of analyzing fossils using modern techniques such as three-dimensional tomography to examine fine details. The teeth of the fossilized lizard are still intact, and its sharp teeth suggest it was a predator, likely used for cutting prey animals to eat, as mentioned by El Periódico.
The name Cryptovaranoides Microlanius means "hidden lizard, small butcher," with the second half referring to the fossil's size and diet, according to Science Alert. The skeleton dates back to a time when reptiles dominated the land and molluscs ruled the sea.
In their research, Dr. Whiteside, Dr. Sofia Chambi-Trowell, and Professor Benton identified many anatomical features of the skull and skeleton of the fossil, placing it within the group Squamata and closely related to Anguimorpha. This placement challenges the rival paper's view that Cryptovaranoides lacks certain features typical of squamates and supports its classification as a modern-type lizard.
The team's fresh analyses demonstrate that the fossil is related to modern anguimorphs such as anguids and varanids, further solidifying its classification within Squamata. This reaffirms the importance of Cryptovaranoides Microlanius in understanding the early stages of squamate evolution.
Concerns were raised from elsewhere in the academic community about the classification of Cryptovaranoides Microlanius. The news of it being the oldest lizard was expected to stir up some controversy, as IFLScience mentioned. However, the Bristol team's comprehensive analysis and detailed rebuttal of criticisms have reinforced their original conclusions.
The article was written with the assistance of a news analysis system.