Fragments of a giant jawbone – 205 million years old – found in 2016 belong to one of the largest ichthyosaurs ever found, said British researchers on Monday.
The skeletal fragments of this long-extinct predatory fish were found on a beach in Lilstock, Somerset, England, in May 2016, according to a study published in the scientific journal PLOS ONE, which specifies that they measure about 96 centimeters long.
Scientists have compared these bones to similar ones that once belonged to what was previously considered the largest ichthyosaur, the 21-meter Shastasaurus Shonisaurus sikanniensis. Their conclusion is that the fragments found in Great Britain come from an ichthyosaur of about 26 meters, the size of a blue whale.
“Since the specimen is represented only by a large piece of jaw, it is difficult to provide an estimate of the size of the animal,” said Dean Lomax, an expert on ichthyosaurs at the University of Manchester. “But using a simple scale factor and comparing it to the same bone of S. sikanniensis, the Lilstock specimen is about 25% larger,” he added.
The fossil remains of ichthyosaurs suggest that they lived throughout the Mesozoic era, 251 million years ago and up to 65 million years ago. They were not considered dinosaurs, but marine reptiles, cousins of lizards and snakes, who depended on air for breathing but did not have gills.
The discovery of this jaw in 2016 also led scientists to re-examine 208 million-year-old bones discovered in 1850 at Aust Cliff in Gloucestershire (western United Kingdom). They have been identified as fragments of members of several different dinosaurs and reptiles. However, researchers now believe they would come from another ichthyosaur, which may have been larger than the Lilstock specimen.
“Size estimates suggest that the Lilstock and Aust ichthyosaurs are the largest known ichthyosaurs,” says the study.
However, paleontologists will not know for sure, until more remains of fossils are discovered, what a giant ichthyosaur of Great Britain really looked like.