Long before dinosaurs cemented their control of the world, prolonged volcanism and rapid climate change brought about an apocalypse known by some as the Great Dying. Up to 90 percent of all life on Earth was wiped out, including 96 percent of all marine species, and the surviving animals began to diversify and spread across the world.
One of these creatures to emerge after the cacophony of doom 252 million years ago was an aquatic, carnivorous marine reptile known as an ichthyosaur, and by the time of the Jurassic Period, they were dominating the world’s oceans. Writing in the Journal of Systematic Palaeontology, a team of researchers have described the discovery of a new species of ichthyosaur after its remains were excavated in Nottinghamshire in the UK.
This new member of the marine family lived 200 million years ago, right at the start of the Jurassic Period, which began just over one million years earlier. Few ichthyosaur fossils are known to date to this period of time, so this new discovery is a huge boost to palaentologists everywhere. Far from being just a new species, it is also the first member of its own genus.
Another fossilized specimen of an ichthyosaur – Stenopterygius quadriscissus – dating to around the Middle Jurassic Period. Haplochromis/Wikimedia Commons; CC BY-SA 3.0
Giving it the scientific name Wahlisaurus massare, after the author’s two palaeontologist mentors Judy Massare and Bill Wahl, the study’s sole author Dean Lomax notes that he first came across the relatively complete specimen in Leicester’s New Walk Museum, where it had been since 1951, and noted that its skull, ribs, vertebrae and pelvis bones seemed peculiar.
“When I first saw this specimen, I knew it was unusual,” Lomax, a palaeontologist and Honorary Scientist at the University of Manchester, said in a statement. “It displays features in the bones – especially in the coracoid (part of the pectoral girdle) – that I had not seen before in Jurassic ichthyosaurs anywhere in the world.”
The bones themselves are fairly disorderly, and Lomax thinks that the carcass of the unfortunate animal “nosedived” into the seabed before becoming fossilized, which partly crushed its delicate and slender snout. Although older than many other ichthyosaur fossils, the morphology of it isn’t too different: It had a fairly long snout, a streamlined hydrodynamic body, strong tail fins and sharp teeth.
A previous study highlighted the fact that the ichthyosaurs diversified into new species surprisingly rapidly after the Great Dying. One specimen dating back to 248 million years ago, just four years after the zoological wipe-out, has a short snout, a lack of large tail fins, a small skull and no teeth. This would have evolved from a currently unidentified land reptile that gradually migrated back into the sea.
As this new study demonstrates, things had changed quite drastically in the following 48 million years. In fact, by this point, the ichthyosaurs were just hitting their stride and dominating the world’s oceans. Unfortunately, they were outlived by the non-avian dinosaurs: They died out around 90 million years ago, whereas the tyrannosaurs and triceratopses of the world bit the dust 24 million years after that.
Plesiosurs (Seeleyosaurus pictured here) eventually replaced the ichthyosaurs as the apex marine predators during the late Jurassic. Dmitry Bogdanov/Wikimedia Commons; CC BY 3.0