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World’s oldest marine reptile found in Arctic revolutionizes paleontology

Ichthyosaur fossil 2 million years younger than previous records puts the species before the age of the Archaea and revolutionizes paleontology

March 14
2023
– 11:06 p.m

(Updated 3/15/2023 at 1:06 PM)

For 190 years, researchers have searched for clues to the origin of marine reptiles during the dinosaur era (Mesozoic era), which was suspected to be after the end of the Permian. Animals in question Ichthyosaurs, its scientific name means “lizard fish,” and it dominated the oceans as a top predator 252 million years ago. However, a new discovery has challenged prevailing theories.

Scientists from Sweden and Norway have explored the remote Arctic island of Spitsbergen and discovered the oldest ichthyosaur known to mankind. The discovery is described in the journal Science Current Biology, and includes little geographic development. In Malar Valley, the mountains have exposed layers of mud that were at the bottom of the sea 250 million years ago and, with erosion, have exposed large limestone boulders. Preserve bones with three-dimensional detail.

Photo: Carpenter, Kenneth/CC-BY-4.0 / Canaltech

What we know about ichthyosaurs

Before understanding the incredible nature of the innovation, it’s important to know what was thought of ichthyosaurs. They were among them The first organisms left the land and adapted to life in the sea Development like open, modern whales. After the Permian, the theories suggest that terrestrial reptiles moved closer to the ocean to hunt marine prey left without predators by mass extinctions at the end of the previous geological period.

Over time, the animals became amphibians through natural selection, becoming more adept at swimming and developing flippers instead of legs, until they were shaped like fish and began to live as young without eggs. They have reached the top of the marine food chain, severing their last link to land without needing to go ashore to lay their eggs. dominates the seas.

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On a 2014 expedition, scientists collected concretions in the Flower Valley and sent them to the Natural History Museum at the University of Oslo with the support of the Museum of Evolution at Uppsala University. Analyzes are revealed Fish fossils Amphibian bones and crocodile-like bones, in addition to 11 articulated vertebrae from the tail of an ichthyosaur. Surprisingly, the rocks that preserve the bones are much older than expected for ichthyosaurs, about 2 million years earlier.

A revolution in reptile evolution

Vertebrates are undoubtedly descended from ichthyosaurs, not even from an amphibious ancestor of animals, but obey all the characteristics of animals. Geographically, they resemble large-bodied creatures, and their preservation has even allowed us to study the internal microstructures of bones, showing the adaptive milestones of rapid growth, high metabolism, and a completely marine lifestyle.

The appearance and diversification of ichthyosaurs also predates the start of the Mesozoic, with rocks dating to 252 million years ago, 2 million years before the Permian mass extinction. The popular view that the age of the dinosaurs was the time when all reptilian lineages appeared has been challenged, showing that some groups appeared before the geological milestone. Scientists are searching for the oldest rocks that hold ancient secrets in Spitsbergen and around the world.

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Source: Current Biology

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