On the News | Vision, not limbs, led fish onto land 385 million years ago @ Science Daily


On the News@ Science Daily


Title: 

Vision, not limbs, led fish onto land 385 million years ago


Excerpt:

A side view of a 3-D model of Tiktaalik in a murky waterway in the Devonian, 385 million years ago, looking out above the water line through eyes set on top of the skull, and breathing through spiracles located just behind the eyes.
Credit: Malcolm MacIver, Northwestern University (@source)

“A provocative new Northwestern University and Claremont McKenna, Scripps and Pitzer colleges study suggests it was the power of the eyes and not the limbs that first led our ancient aquatic ancestors to make the momentous leap from water to land. Crocodile-like animals first saw easy meals on land and then evolved limbs that enabled them to get there, the researchers argue.

Neuroscientist and engineer Malcolm A. MacIver of Northwestern and evolutionary biologist and paleontologist Lars Schmitz of Claremont McKenna, Scripps and Pitzer colleges studied the fossil record and discovered that eyes nearly tripled in size before — not after — the water-to-land transition. The tripling coincided with a shift in location of the eyes from the side of the head to the top. The expanded visual range of seeing through air may have eventually led to larger brains in early terrestrial vertebrates and the ability to plan and not merely react, as fish do.

“Why did we come up onto land 385 million years ago? We are the first to think that vision might have something to do with it,” said MacIver, professor of biomedical engineering and of mechanical engineering in the McCormick School of Engineering.

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“We found a huge increase in visual capability in vertebrates just before the transition from water to land. Our hypothesis is that maybe it was seeing an unexploited cornucopia of food on land — millipedes, centipedes, spiders and more — that drove evolution to come up with limbs from fins,” MacIver said. (Invertebrates came onto land 50 million years before our vertebrate ancestors made that transition.)” (…) READ MORE