Wahlisaurus massarae: Paleontologists Find 200-Million-Year-Old Ichthyosaur Fossil
The 200 million-year-old specimen is only the second known example of Wahlisaurus massarae, a species of ichthyosaur announced recently by a University of Manchester paleontologist.
Ichthyosaurs were predatory sea-going reptiles that ranged in size from 1 to 69 feet (0.3-21 m) long. They swam the world’s oceans for millions of years during the Triassic, Jurassic and Cretaceous periods.
Despite their profound adaptations to the aquatic realm, these reptiles disappeared about 30 million years before the end-Cretaceous mass extinction (65 million years ago) that marked the end for dinosaurs and the beginning of the age of mammals.
In 2016, a paleontologist and honorary scientist at the University of Manchester, Dean Lomax, described an ichthyosaur skeleton that he had examined in the collections of Leicester’s New Walk Museum and Art Gallery.
He spotted several unusual features of the bones and determined that the features were unique and represented a completely new species, Wahlisaurus massarae.
“When Wahlisaurus massarae was announced, I was a little nervous about what other paleontologists would make of it, considering the new species was known only from a single specimen,” Lomax said.
“As a scientist you learn to question almost everything, and be as critical as you can be.”
“My analysis suggested it was something new, but some paleontologists questioned this and said it was just ‘variation’ of an existing species.”
In the new study, Lomax teamed up with New Walk Museum paleontologist Mark Evans and Simon Carpenter, fossil collector of Somerset.
The study focuses on a specimen Lomax identified in Simon’s private collection, which is an almost complete coracoid bone (part of the pectoral girdle) that has exactly the same unique features of the same bone in Wahlisaurus massarae.
“You can only imagine my sheer excitement to find a specimen of Wahlisaurus massarae,” Lomax said.
“It was such a wonderful moment. When you have just one specimen, ‘variation’ can be called upon, but when you double the number of specimens you have it gives even more credibility to your research.”
The new discovery is from a time known as the Triassic-Jurassic boundary, right after a world-wide mass extinction.
For these reasons, the authors have been unable to determine exactly whether the ichthyosaur was latest Triassic or earliest Jurassic in age, although it is roughly 200 million-year-old.
D.R. Lomax et al. 2018. An ichthyosaur from the UK Triassic-Jurassic boundary: A second specimen of the leptonectid ichthyosaur Wahlisaurus massaraeLomax 2016. Geological Journal, in press; doi: 10.1002/gj.3155