A Fossil Collector's Giant Icthyosaur Jawbone Discovery Just Solved an Ancient Mystery

Tuesday, 10 April 2018 - 11:34AM
Earth
Tuesday, 10 April 2018 - 11:34AM
A Fossil Collector's Giant Icthyosaur Jawbone Discovery Just Solved an Ancient Mystery
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Image credit: Nobumichi Tamura

A female blue whale living in the northern hemisphere is about 82 feet long, but luckily for seafaring humans, they only feed on krill. That wasn't the case for the ichthyosaur, a giant aquatic dinosaur that swam the oceans of the Triassic period: these giant, finned lizards were predators and fed on everything from fish to squid.

 

Paleontologists have known about ichthyosaurs for decades, but two years ago, Paul de la Salle stumbled across the jawbone of the biggest one yet on a beach in England. 

 

Paleontologists estimate the original animal to be about the size of the modern blue whale—around 85 feet long. On top of that, la Salle may have solved a long-standing mystery about similar bones found in the UK.

 



Previous research showed ichthyosaurs varied in length, from just a few centimeters (at the smallest) to around 15 meters (at the largest).

 

According to the current theory, they were not fish, but rather dinosaurs whose ancestors had moved onto land...then returned to the ocean.

 

In general, they look like large dolphins with fat bodies and long snouts. They disappeared during the cretaceous period, several million years before the rest of the dinosaurs.

 

This new jawbone changes our picture of ichthyosaurs dramatically—not only does it beat out the largest-known shastasaurid, the 69-foot Shonisaurus sikanniensis, it may reveal that mysterious bones discovered in other parts of the UK are also from giant ichthyosaurs:



"This specimen has prompted the reinterpretation of several large, roughly cylindrical bones from the latest Triassic (Rhaetian Stage) Westbury Mudstone Formation from Aust Cliff, Gloucestershire, UK. We argue here that the Aust bones, previously identified as those of dinosaurs or large terrestrial archosaurs, are jaw fragments from giant ichthyosaurs."



All in all, we're glad ichthyosaurs ended up drawing the short evolutionary straw—we ended up with peaceful, lovable blue whales rather than murderous giant dolphins.

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