A new scientific study led by researchers at The University of Manchester has re-examined a series of fossil skulls from the UK, providing new insights into two species of extinct marine reptiles.

Dr Dean Lomax, a palaeontologist at The University of Manchester, worked with colleagues from the University of Leicester and the State University of New York to investigate fossilised 3D skulls of 190 million-year-old ichthyosaurs from the Early Jurassic.

Whilst researching the fossil collections of the New Walk Museum, Leicester, England, the team studied an almost complete skull of an ichthyosaur with all of the bones of the skull roof preserved, in exceptional detail.

The find provided new information about the anatomy of the skull in a species known as Protoichthyosaurus.

Previously, many Protoichthyosaurus fossils had thought to be the same as a closely related, but contemporary species called Ichthyosaurus. However, in 2017, Lomax and his team found that the two species differed greatly in the number of fingers on each limb, which has been the key characteristic used to tell them apart.

“Protoichthyosaurus has three 'primary' fingers, whereas Ichthyosaurus always has four 'primary' fingers,” explains Dr Lomax. However, this was not always sufficient to tell the species apart, as many fossils are only partial fragments of the original animal, so confusion remained.

In the new study, the researchers have identified a further difference between Protoichthyosaurus and its close cousin, based on the skull at New Walk Museum and Art Gallery, Leicester. They found that the two ichthyosaurs vary in the shape of the skull, and particularly how the individual skull bones fit together.