The rediscovery of a prehistoric crocodile species

Image credit: Sven Sachs via UoE Media

Two and a half centuries after their discovery, the fossil remains of a mysterious creature has been identified as a new species. The remains turned out to belong to Mystriosaurus Iaurillardi – a Jurassic relative of modern-day crocodiles. 

The fossils were discovered in Altdorf, a town in southern Germany, in the 1770s, and were established as the holotype of Mystriosaurus Iaurillardi. This means that the M.laurillardi species was discovered, described and established based on that particular fossil skull. Meanwhile, another fossil skull, found in Yorkshire, UK in the 1800s, was identified as belonging to the species Steneosaurus bollensis. Both species existed at the same time but had clear differences in anatomy. Moreover, the Mystriosaurus laurillardi was believed to have been a subspecies of S. bollensis. The recent reassessment in which Edinburgh scientists took part, compared the two skulls, revealing that both skulls belong to the Mystriosaurus, and even more significantly, discovered that, contrary to the existing belief, Mystriousaurus was a whole separate genus which S. bollensis was a part of. 

Both species existed at the same time but had clear differences in anatomy.

During the Jurassic era, the map of Europe looked different from the one we know today, where the continent was fragmented into groups of islands. The geographical range of the two findings illustrate that M.laurillardi was a marine species, like a modern day saltwater crocodile, and could swim easily between the islands. It had a long snout and pointed teeth and preyed on fish. One of the main features that allowed scientists to distinguish its fossils from the others was the location and position of the nostrils. In M. laurillardi the nostrils are at the end of the snout facing forwards, whereas in other fossils and modern day crocodiles the nostrils are on the top of the nose. 

The holotypes of the two species have never been compared before and haven’t been redescribed for the past 100 years, so to carry out the study many different methods were employed. The skulls were measured and compared in detail. The scientists looked at and recorded the position of different bones as well as the nostrils and carried out the comparison based on this information. Additionally, they analysed its evolutionary relationships with other species and concluded that Mystriosaurus Iaurillardi is more closely related to the Chinese telesauroid than any other fossil species. 

The holotypes of the two species have never been compared before and haven’t been redescribed for the past 100 years.

According to Dr Mark Young, from the School of GeoSciences at the University of Edinburgh, this discovery is crucial for the understanding of the diversification of crocodiles in the Jurassic era. Between 200 and 180 million years ago there was a rapid increase in their biodiversity, and it is still poorly understood and understudied today.

Written by Natalie Nosenko and edited by Tara Wagner-Gamble

Leave a Reply

Your email address will not be published. Required fields are marked *