Evolution: food as well as oxygen allows speedy change (Evolution)

by David Turell , Thursday, December 23, 2021, 22:01 (854 days ago) @ David Turell

A huge reptile ocean form developed rapidly:

https://www.newscientist.com/article/2302957-prehistoric-ichthyosaurs-evolved-rapidly-t...

"Ichthyosaurs were marine reptiles that lived between about 249 million and 90 million years ago and had a body shape reminiscent of modern whales and dolphins. Some grew large, and C. youngorum was comparable in size to a modern sperm whale.

"It was discovered in roughly 246 million-year-old rocks, so it is only about 3 million years younger than the first ichthyosaurs, which evolved from land-based ancestors. This indicates that ichthyosaurs ballooned in size astonishingly quickly once they took to the seas.

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"The ecosystem that hosted C. youngorum wasn’t like the seas today. “The food chains were shorter,” says Schmitz, with a proliferation of creatures, including ancient squid relatives called ammonoids, that would have provided ample sustenance for marine reptiles.

"The glut of seafood allowed large ichthyosaurs to evolve and sustain themselves. Based on models of energy flow through the ancient food web, Schmitz notes that another giant-size ichthyosaur species could have survived in the same environment. Whales didn’t get the benefit of such a surfeit, and so took a much longer path to becoming leviathans."

Comment: the food supply controls the speed of evolution to some degree, just as it is assumed oxygen does, but neither substance, causes the speed. but allows it. This is why dhw's complaint about 'humans and their food' is so silly.