For the past 100 million years, crocodiles and their close relatives – including alligators, caimans and gharials – have survived dramatic changes in climate and habitat. They’ve even endured mass extinctions, including the event that wiped out the dinosaurs 66 million years ago. Yet, despite all this, their brains have changed very little, according to new research.
Published in the Journal of Anatomy, the study suggests this shows that these predatory reptiles developed an extremely effective brain design tens of millions of years ago, when they first started to evolve. The design was so successful, in fact, that there was no real need for it to change.
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Using advanced CT scanning technology, researchers from the Swedish Museum of Natural History were able to look inside the skulls of both modern crocodilians and their extinct relatives.
They examined 43 species, including living species – such as the American alligator (Alligator mississippiensis), the Yacare caiman (Caiman yacare) and the Nile crocodile (Crocodylus niloticus) – and extinct species.
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The team made an interesting discovery about how closely extinct species were related.
In the past, scientists have found this hard to do because the fossil skulls of these long-lost reptiles look so similar. But by using CT scans to study the hidden structures inside the skulls, the researchers found key differences in the braincase and sensory organs that helped them differentiate between species that looked almost indistinguishable on the outside.
Understanding the inner structure of the extinct reptile skulls also meant the study authors could work out how much the basic form of their brains and inner ears have changed through time – and how they compare with today’s species.
It turns out the brains of crocodiles and their close relatives have remained mostly unchanged.
Co-author Paul Burke says the discovery helps explain how these reptiles have survived for more than 100 million years, while other vertebrate animals that once existed alongside them succumbed to mass extinctions and other major environmental changes and events.
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