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Ancient fish were “prepared” for life on land


Well, that’s what they are saying about sarcoptergians, some of the earliest animals in the Devonian Period (359-419 million years ago):

Using micro-CT and MRI scans to make 3D models of small animal heads, palaeontology researchers from the University of Edinburgh, University of Calgary and Flinders University shone a light on how the eating habits and brains of the some of the first land-based lifeforms prepared them for life on dry land.

University of Edinburgh researcher Dr Tom Challands says the high-tech scanning of braincase and jaw structure in six sarcopterygians shows a correlation between how tight or loose the brain fills the skull.

“For the first time, we have been able to demonstrate the interplay between how the jaw muscles affect how the brain sits inside the brain cavity,” says first author Dr Tom Challands, from University of Edinburgh’s Grant Institute of Earth Sciences.

“As animals made their way out of water and on to land, their food sources changed and the brain had to adapt to a completely new way of living — different sensory processing, different control for movement, balance, and so on,” he says.

“Each of these plays against each other and our work basically shows the effect of masticatory (eating) changes are balanced with maintaining a skull that can support and protect the brain.”

He says some of the features of these earliest land animals is reflected in other modern animals.

“Moreover we see similarities between the fish and land animals, suggesting that some muscle-brain-skull arrangements were already primed for living on land.”

Flinders University, “How ancient fish may have prepared for life on land” at ScienceDaily

Paper. (open access)

Now how would the sarcoptergians have come to be “already primed for living on land”? Did they know they were going to move to land? Or is there an underlying pattern? Can we call this “preparatory evolution?”

There's a broader question. Most widespread and successful phyla have both land and sea members. Arthropods, molluscs, vertebrates. The land dwellers often have equipment and reflexes for living in water, even though rarely or never used. Some sea dwellers can live on land when necessary. Evolution had to anticipate that the earth would go through cycles with high water and low water, and had to mutate both sets of equipment in advance of the weather patterns. Otherwise all phyla would have died out when the "wrong" sea level was present. polistra
https://stuffhappens.info/repeated-evolution-a-fish-out-of-water-is-not-an-extraordinary-thing-but-a-common-phenomenon/ martin_r

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