An article published in “Journal of Systematic Palaeontology” describes the identification of a new spiecie of ichthyosaur (image ©Nobu Tamura), a group of marine reptiles that lived in the Mesozoic Era. Called Wahlisaurus massarae, the only known specimen lived in the Lower Jurassic period, about 200 million years ago, in today’s Nottinghamshire, England.

Ichthyosaurs – order Ichthyosauria – have been already known and studied for over two centuries but their origin is still the focus of discussions because the oldest fossils associated with this group of reptiles indicate species already fully adapted to marine life. The oldest fossils date back nearly 250 million years ago but already show a diversification of species indicating an earlier origin.

In the past there were those who even suggested that they were not reptiles but animals that had evolved separately from amphibians to explain the absence of transitional forms. Today paleontologists think that the problem is only in the lack of fossils of ichthyosaur ancestors and primitive forms of these reptiles.

The ichthyosaur species existing in the Lower Jurassic already show a remarkable variety within this group with very different sizes. However, there aren’t many available fossils from that period so every new discovery is significant. For this reason, the circumstances of Wahlisaurus massarae identification are all the more curious.

The paleontologist at University of Manchester Dean Lomax examined the specimen of Wahlisaurus massarae after seeing it during a visit to the Leicester’s New Walk Museum. This fossil was acquired in 1951 but was neglected for decades. The only study was carried out by Dr. Robert Appleby, who unfortunately died before publishing his discoveries.

The specimen of Wahlisaurus massarae is incomplete but there are enough bones to see its features. In particular, its coracoid, a bone of its pectoral girdle, is different from those of other known ichthyosaurs of the Jurassic. According to Dean Lomax this ichthyosaur belongs to the Leptonectidae family and its identification is evidence that new species can also be found by re-examining fossils that has been for some time in museums and collections.