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Convergent evolution of crocodile and dolphin skull shapes


From ScienceDaily:

Dolphins and crocodiles now live in rivers and oceans, but each evolved from land-based animals. Feeding in water has many new challenges. This new study shows that despite being separated by 300 million years, dolphins and crocodiles found comparable solutions to these problems, and evolved skull shapes that are remarkably similar.

“Our results suggest the remarkable similarity between some crocodilians and toothed whales is driven by what they eat rather than where they live,” said lead author Mr Matthew McCurry from the Monash School of Biological Sciences.

Previously no rigorous attempt had been made to show how similar the head shapes of dolphins and crocodiles really are. It had been thought that aspects such shallow seas or rivers contributed to the similarity of the skulls of crocodilians (crocodiles and alligators) and toothed whales (dolphins, orca and relatives). But a study published in Proceedings of the Royal Society B: Biological Sciences has debunked this long-held view.

Having a long, thin snout must have great advantages when trying to catch small fish, both for crocodilians and toothed whales. Paper. (paywall) – Matthew R. McCurry, Alistair R. Evans, Erich M. G. Fitzgerald, Justin W. Adams, Philip D. Clausen, Colin R. McHenry. The remarkable convergence of skull shape in crocodilians and toothed whales. Proceedings of the Royal Society B: Biological Sciences, 2017; 284 (1850): 20162348 DOI: 10.1098/rspb.2016.2348 More.

The authors don’t mention this but the find means — according to Darwinian theory — that vast numbers of complexities evolved independently twice, by natural selection acting on random mutation. Take that in and we see why there is a problem with Darwinism as “evolution,” generally.

See also: Evolution appears to converge on goals—but in Darwinian terms, is that possible?

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