A NEW study of fossilised teeth has revealed not all the ancestors of today’s crocodiles were cold-blooded, with research showing at least one species was warm-blooded. Palaeontologists and other researchers from the University of Edinburgh analysed the mineral make-up of teeth from a metriorhynchid, an extinct family of marine crocodile.
The results indicated the species could raise their body temperature to stay warm in falling temperatures in the same way as modern-day birds and mammals. And it might have helped them survive a cooling of the seas at the end of the Jurassic period.
Dr Mark Young from the University of Edinburgh said: “This discovery helps us better understand these bizarre crocs. They rapidly changed from animals looking similar to modern long-snouted crocodiles, to ones with flippers, a tail fin and massive, forward-facing eyes.
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“Their transition from land to sea dwellers increasingly mirrors the better-known transformation undergone by dolphins and whales millions of years ago.”
This likely allowed the animals, which lived during the Jurassic and Cretaceous periods, to thrive during global cooling around 150 million years ago.
The fact they were warm-blooded was key to the animals evolving a dolphin-like body with flippers and a tail fin and led them to venturing out to live in open oceans, the scientists say.
Oxygen levels in the fossil tooth enamel were affected by the animals’ body temperature and measuring them allowed researchers to find out whether they were cold or warm-blooded.
The study was published in Philosophical Transactions of the Royal Society B: Biological Sciences.
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