New CT scans of 43 species of crocodiles – living and extinct – reveal a brain design so efficient that they survived the extinction of the dinosaurs largely untouched.
Crocodiles have lived entire eras of life on land. They were already an established race when the asteroid struck that wiped out the dinosaurs 66 million years ago, and they continued their lives largely undisturbed while countless other groups disappeared. A new study provides new insight into how this plasticity manifests itself in animal anatomy, tracing a surprising degree of stability in the crocodile brain over a very long period of evolutionary time.
The research, published in the journal Anatomy, comes from a team led by Paul Burke, a postdoctoral researcher at the Swedish Museum of Natural History. Using high-resolution computed tomography, the researchers reconstructed the internal cranial anatomy of 43 species of crocodiles, both living and extinct.
What the scans revealed
crocodile Fossils appear almost everywhere. Fossil crocodiles have been found on almost every continent, a reflection of how extensive this group’s range was before its living members settled the tropical waterways they occupy today.
But distinguishing extinct species from others has long been difficult, since their skulls, when viewed from the outside, tend to look depressingly similar.
CT scanning has helped address this problem by allowing researchers to look beyond the outer bone to the brain and inner ear structures hidden within. These internal traits carried much more information about how different species were related to each other than external appearance alone, and allowed the team to clarify relationships between extinct groups that had previously been difficult to resolve.
More of LifestyleOne of the central findings of the study concerns the shape of the snout. Long, narrow snouts evolved independently several times throughout the history of crocodilians — a case of convergent evolution — and the internal anatomy revealed by the scans helped researchers distinguish which of these narrow-snouted species were closely related and which arrived at a similar shape separately, through unrelated evolutionary paths.
Besides, the researchers found that the basic structure of the brain and its sensory anatomy remained relatively stable throughout crocodilian history, even as skull shapes varied greatly. Why this stability remains has not been fully explained in study coverage, although it is consistent with the broader idea that crocodilians arrived at a working anatomical template early on, one that did not require significant revision even as the group diversified and the world around them changed.
