Museums are not only valuable for what they display, but also for what they hide. Sometimes they store real treasures that, once they come to light, can change what was believed about some chapters of natural history. This is the case of a small lizard that 70 years went unnoticed in a closet from the storage room of the Natural History Museum in London until a team of researchers noticed him. The fossil turned out to be exceptional. Their existence shows that modern lizards originated 35 million years earlier than previously thought, in the Late Triassic (about 230-199 million years) and not in the Middle Jurassic (174-166 million years).
The lizard has been named ‘Cryptovaranoides microlanius‘. The first part of its name means ‘hidden lizard’, both from having remained in a drawer and also from the fact that it lived in crevices in the limestone on small islands that then existed around Bristol. The second part of its name is ‘little butcher’, due to its jaws full of sharp teeth for cutting. It probably fed on arthropods and small vertebrates. It is related to living lizards such as monitors or gila monsters, but when it was discovered in the 1950s no one knew how to recognize its value, as the technology to expose its contemporary features did not exist then.
The fossil was stored in a museum collection, including specimens from a quarry near Tortworth in Gloucestershire, southwest England. The technology to expose its contemporary features did not exist then.
David Whiteside, from Bristol’s School of Earth Sciences, first saw the specimen in a cupboard full of fossils in the museum’s storerooms, where he is an associate scientist. The lizard was listed as a fairly common fossil reptile, a close relative of the New Zealand Tuatara, which is the sole survivor of the Rhynchocephalia group, which diverged from scaly lizards more than 240 million years ago.
The scientists X-rayed the fossil, reconstructed it in three dimensions, and realized that it was actually more related to modern lizards than to the Tuatara group.
Like boas and pythons
As the team explains in the journal ‘Science Advances’, Cryptovaranoides is clearly a squamous due to different physical characteristics, such as the neck vertebrae, the way in which the teeth are placed in the jaws, the architecture of the skull, etc. There is only one important primitive feature that is not found in modern squamates, an opening on one side of the end of the upper arm bone, the humerus, through which an artery and a nerve pass.
In addition, the fossil has some other apparently primitive features, such as a few rows of teeth on the roof of the mouth bones, but experts have observed the same in the modern European glass lizard. And many snakes like boas and pythons have multiple rows of large teeth in the same area.
“In terms of significance, our fossil shifts the origin and diversification of squamoses from the Middle Jurassic to the Late Triassic,” says Mike Benton, co-author of the study. “This was a time of great restructuring of terrestrial ecosystems, with the origin of new groups of plants, especially conifers, as well as new types of insects, and some of the first modern groups such as turtles, crocodiles, dinosaurs, and mammals,” Explain.
“Adding the older modern squames completes the picture. It seems that these new plants and animals came on the scene as part of a major reconstruction of life on Earth after the end-Permian mass extinction 252 million years ago, and especially the Carnian Pluvial Event, 232 million years ago. when climates fluctuated between humid and warm and caused great disturbance to life.”
For the researchers, “this is a very special fossil and it is likely to become one of the most important found in recent decades.”