Saturday, December 5, 2009

The Other California: Geology and the other State Symbols, Part III

I was walking alone a couple of years ago in Yosemite Valley, on a surprisingly lonely trail between the visitor center complex and Yosemite Falls. Yes, I know all that about not hiking alone, but I thought it was a busy trail and a short distance. Just the same I was enjoying myself, having found a bit of solitude in a very busy park. Until I got spooked. It wasn't that I saw or heard anything. It was that I didn't hear anything. It had been a few weeks since a mountain lion attack somewhere in the state, and I was walking along these huge boulders that had fallen from the cliffs above, and any of them would provide a great hiding place for the big cats.

Nothing happened, of course. My life has not been THAT interesting yet. But it got me thinking. Grizzly Bears have been extinct in the state since the 1920's. The remaining black bears have not caused a single fatality in Yosemite since the park was established (they have been a lot nicer to us than we have been to them). Despite a few newsmaking exceptions, cougars have not been much of a threat to humans. We have a better chance of dying from bee stings and car accidents. This has not always been the case in California.

Prior to 12,000 years BP, our state would have been an intimidating place. Packs of Dire Wolves and American Lions roamed our prairies, seeking their prey from among the herds of horses, camels, antelope, bison, elk, mastodons, and mammoths. Short-faced bears, larger than grizzlies and polar bears, would have at least considered having you for lunch. In more forested and brushy areas, the large plant-eaters faced a threat from one of the most intimidating predators of all, the saber tooth cat (Smilodon californicus).

The largest cougars today weigh in at 200 lbs or so. The saber-tooths were more like 700 lbs or more! They were heavily built, especially in the front, giving them in advantage in stealthy ambushes. Their dagger-like serrated fangs could be 11 inches long. They didn't waste time chasing their prey, they jumped, bit, and waited for the victim to bleed to death. Evidence suggested they worked in social units, somewhat like wolves (many specimens show evidence of recovery from broken bones that would have led to the death of solitary predators).

The La Brea Tarpits in Los Angeles provide one of the richest records of the Ice Age predators to be found anywhere in the world. Trapped plant-eaters attracted large numbers of predators to the pools of sticky tar, and the hunters were trapped as well (something like 90% of the specimens recovered are predators). Portions of 1,200 saber tooth individuals have been found so far, allowing for all manner of population variability and growth studies to take place.

From about 1.6 million years until just 10,000 years ago, the sabertooths and other large animals dominated the ecosystem of California. Their disappearance is linked to severe climate changes in the aftermath of the most recent ice age, or to overhunting by newly-arrived humans. The issue of the North American megafauna extinction is one of the more intriguing mysteries of the present day.

The Smilodon californicus was selected as the state fossil of California in 1973, beating out the trilobite species Fremontia fremonti for the honor. I understand the desire of many of the paleontologists to have a trilobite named the state fossil, but I must say I get a lot more oohs and ahs from elementary students when they see my Smilodon skull during their visits at the department. They are absolutely fascinated to find that the animal once lived, quite literally, in their backyards. So do I!

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