The find, described in Science, comes from the Arctic island of Spitsbergen, a remote territory in Norway that was already famous for preserving rocks from the beginning of the Age of Dinosaurs. But this new site surpasses everything known: it offers an extremely detailed snapshot of how life in the ocean was rebuilt after the largest mass extinction in history.
A window to the “first explosion” of marine reptiles
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The collection – more than 30,000 fossils – reveals a complex community where completely aquatic reptiles, marine amphibians, sharks and bony fish coexisted. It is, according to the authors, the first radiation of terrestrial animals to oceanic environments after the global collapse that occurred at the end of the Permian, 252 million years ago.
That episode, known as the Great Dying, eliminated more than 90% of marine species due to a hyperwarm climate, acidified oceans and oxygen-depleted zones caused by a volcanic supercycle that disintegrated Pangea.
Until now, it was believed that the recovery of marine ecosystems had been slow and progressive, extending over about 8 million years. But this site challenges that idea.
A bed of bones formed in a short time
The Spitsbergen site consists of dense bone bed eroding into a mountainside. Its origin corresponds to a brief geological period, allowing the structure of a complete ecosystem to be reconstructed with remarkable precision.
Stratigraphic dating indicates that the complex is 249 million years old, just 3 million years after the mass extinction. Already at that time there were:
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Primitive ichthyosaurs
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Marine archosauromorphs, distant relatives of crocodiles
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giant amphibians
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Sharks and bony fish
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Coprolites (fossilized feces) that allow us to reconstruct diets and food chains
The level of diversity surprised even the authors: it is one of the most species-rich marine ecosystems ever documented for that time interval.
Rapid recovery or previous evolution? The debate reopens
Global comparative analyzes suggest that oceanic reptiles were much more diverse—and perhaps older—than previously thought. It is possible that its origin predated the Great Dying, and that the event simply opened ecological niches that facilitated its expansion.
This involves rewriting part of the evolutionary history of marine reptiles and how vertebrates colonized the oceans again after a global cataclysm.
An unprecedented natural archive
The Spitsbergen site, excavated and analyzed for almost a decade by teams from Oslo and Stockholm, thus becomes a fundamental archive for understanding how life is reborn after a global crisis.
Its scientific message is forceful: even after the most devastating collapse in history, life quickly diversified again, generating complex ecosystems that would be the prelude to the seas dominated by reptiles during the Triassic and Jurassic.
Fuente: Meteored.
