Friday, August 18, 2023

What the LA Tar Pits has to say about earlier extinction

For those of you that have not been, the LA Tar Pits is something a little odd. It is there that hundreds, if not thousands, of fossilized animals are in the pits, now about the size of a city block (I don't know how big they were thousands of years ago).

It hold the remains of hundreds of types of animals, many of which are long gone and extinct, because of it's unique contents. The pits look like dirty ponds, but are really full of tar. Large animals went in accidentally, or looking for food, and got stuck. Predators of the times, saber tooth tigers, dire wolves, and American Lions, would go in to feast on the captured animal, only to get stuck them selves.

But there has always been a bit of a mystery. And about 13,000 years ago, many of the animals in the region went extinct. In fact 7 of the 8 large animals were gone. It has been a mystery for a while why they all died off at once. It turns out, it was a lot of things.

The biggest cause seems to be the more adaptable humans entered the scenes in the exact wrong time. Previous to 13,000 years ago the Southern California region had a rich plant and animal life. It all changed overnight (in epoch time frames) and the animals here were wiped out. So what happened?

Slightly deceptive headline LINK

First climate change (10 degrees over 1,000 years) meant that clearing the forest and mature plants led to a spread of dry grasses and chaparral. These areas were cleared of all the major grazers first - ancient camels, horses, elephants and giant sloths - by human hunters. Taking the grazers away accelerated the growth from healthy plants and grasses. But the grasses grew too large with out the grazing animals to eat it. The killings of all the mega-fauna grazing animals left the sabertooth tigers, American lions and dire wolves to starve. Oddly coyotes escaped this relatively unchanged because of their diets of scavenged foods and small prey that they feed on.

Once the grazers were killed, giant fires ripped through the Southern California plants and trees, and were replaced with chaparral, which cannot support large grazing animals or the very large prediters.

It is an interesting article, belied by a rather confusing headline.

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