New Delhi: The fossil of a Westolithiana Lizziae, nicknamed Lizzie, was known to be the oldest reptile in the archeological community. However, new scans of the fossil have revealed gills, a primitive skull and thousands of tiny teeth suggesting that Lizzie was not a reptile after all.
Lizzie was discovered in 1984 in Scotland and described in 1990. She is nearly 345 million years old and her lizard-like body’s skeleton was preserved between two crushed slabs. Lizzie’s four limbs, five digits on each, and claw-like hands and feet were very different from other animals of the time, many of whom had fin-like limbs. However, even though the specimen might have been nearly complete, the fossil itself was deformed and researchers were making their interpretations about its anatomy based on what they could see on the surface.
At the time, scientists assumed that Lizzie was one of the earliest reptiles and classified her as a Westlothiana, an early amniote, part of the vertebrate group that included reptiles, birds, and mammals, that had just adapted to living on land. Amniotes are a part of the larger family of tetrapods, a group of early four-limbed vertebrates.
However, a recent study, published in Nature led by researchers at the University of Oxford and the American Museum of Natural History has established that scientists were wrong about Lizzie.
The findings, based on X-ray scans, allowed researchers to look deeper into the anatomical features hidden inside the fossil. The fossil had a primitive skull, ossified gills, and even a fish-like mouth that was lined with hundreds of tiny teeth. These findings rule out the possibility of Lizzie being a reptile and suggest that she lived predominantly in water and maybe moved around a little between water and land.
The highlight of the discovery is that it has changed what scientists have so far understood about the evolution of the limbs and other such body parts associated with life on land. Although they assumed that five digits, feet, and claws were characteristics of animals that had adapted to land, scans of Lizzie are evidence that many of these traits might have evolved already even in animals that lived mainly in the water. The findings further suggest that the transition from water to land was a more complex evolutionary step.