Discovery of Oldest Ichthyosaur Fossil Shatters Previous Theories

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4 min readMar 16, 2023

Fossils discovered on Spitsbergen are shedding new light on the origins of the oldest marine reptiles. It turns out that ichthyosaurs appeared on Earth many millions of years earlier than we thought.

[Photo: Ghedoghedo, CC BY-SA 3.0, via Wikimedia Commons]

Scientists to this day are unsure how the first marine reptiles that dominated the oceans and stood at the top of the food chain of their ecosystem evolved. The most common theory is that the oldest reptiles living in the seas came together in the period that followed the Permian extinction, some 251 million years ago. The cataclysm caused many species to have to adapt to the new reality on Earth, and the evolutionary development of some creatures followed.

Fossil of oldest ichthyosaur sheds new light on origins of marine reptiles

A recent study, however, sheds new light on the genesis of marine reptiles on our planet. The fossils of an ichthyosaur unearthed on the Arctic island of Spitsbergen have been analyzed by paleontologists. This is the largest island in the Svalbard archipelago, which belongs to Norway. A team of Swedish and Norwegian scientists says that the surprisingly large size of this individual and some features of internal structures indicate that the animal was one of the survivors of the extinction period. This means that the species was older than previously thought.

The work of the Scandinavian researchers was described in the pages of the scientific journal Current Biology. Until now, it was thought that ichthyosaurs appeared just after the Permian extinction, and reached their greatest diversification from the Middle Triassic to the Middle Jurassic. Scientists believed that reptiles first entered open water after the first dinosaurs were born and dominated coastal ecosystems (about 250–252 million years ago).

Ichthyosaur and Plesiosaur — [Photo: EDOUARD RIOU (ENGRAVED BY LAURENT HOTELIN AND ALEXANDRE HUREL, Public domain, via Wikimedia Commons]

When did the first ichthyosaurs appear?

According to some theories, small reptiles displaced by predatory dinosaurs adapted to life in the oceans over time to such an extent that they became the head of their own food chain…