Paleo Day / night cycle

Indricotherium

https://www.theguardian.com/science/2015/dec/11/climate-change-longer-days-glaciers-north-south-pole

Had a read of this the other day.

It got me to wondering if there is any study of day/night patterns of the earth.

If there was a significantly longer or shorter day night cycle in the very distant past and if it may have had some influence on the evolution of different species.

For example, would a significantly shorter day night cycle, say 20 hours, lend itself to the evolution of enormous cold blooded lizards. Or would some sudden change to the day night cycle, such as what could be caused by a massive asteroid impact, alter the length of the the day night cycle to such a degree that it would put creatures that had significantly committed to one evolutionary pathway under significant survival pressure.

I've read that (grand scheme) minor changes in the earths temperature can more or less write off animals like giraffes that are well committed to specific niches.

Wibbs

Bloody good question!. For me the moon earth distance has always fascinated me for similar reasons. Go back to the earliest life and the moons pull on the oceans was much more intense and tides would have been huge. Couple that with shorter days and nights and the such extremes of heat and (relative) cold and wet and dry conditions on shorelines would make it more likely for the chemistry of life to kick off in the first place.

Indricotherium

Wibbs wrote: »

Bloody good question!. more likely for the chemistry of life to kick off in the first place.

It didn't occur to me to consider it in that regard.

I've never read anything about the study of the day night cycle over the course of the earths existence, but I fell I've definitely read that the earths rotation is gradually slowing. Even if a day was only lengthening a second a millennium it would add up eventually.

I was looking at it in the other direction, that even a small change in the day night cycle would put huge pressure on creatures or plants very committed to an extreme survival trait - think long necks, or giant size, or hyper developed single traits - elephants, giraffes, whales, cheetahs, sequoia, tigers -

But it seems that sudden changes are possible also, whether by shifting the earths magnetic poles, by quickly melting the ice caps to redistribute mass, or presumably, by a big impact or big eruption.

An hour off a day over the course of a year, would drastically reduce the cumulative sunshine a particular place gets over the course of a year. I can only imagine the effect this would have on locally adapted plant life, and on up the food chain.

Moving potted plants around my kitchen can cause extinction events.

Capt'n Midnight

Roll the clock back far enough and the day was 6.5 hours long. The Moon was 10 times closer. So IIRC 100 times as much moonlight and ginormous tides.