Friday, September 04, 2015

Mammoths in the news

Note: I really need to put up more mammoth news without thinking I need to write a dissertation about each one. I have about twenty unfinished posts that fell prey to that impulse.

Here's a new mammoth find from San Diego.

In July, a work crew preparing the ground for a huge, one might even say mammoth, housing development started coming across big bones. California law requires construction projects that move large amounts of earth to have a paleontologist on site (he probably doubles as an archaeologist). Usually, with projects like this, someone is standing over the excavation tapping their foot moaning over the time being lost. In this case, the were able to move the work to another part of the project, which covers sixty acres. John Suster, the project superintendent, told the scientists "Take your time, this is kind of cool." Even Ure Kretowicz, the CEO of the development company, seems excited about it.  

So far they've found mammoths, horses, turtles and an undetermined species of bison. The mammoths are Columbian mammoths; woollys didn't live that far south. Woollys and Columbians are siblings. Both are descended from the steppe mammoths that lived in Eurasia six million years ago. Before the ice ages, steppe mammoths colonized North America, just one of many imperialist intrusions from that direction.

Steppe mammoths were adapted temperate grasslands. As the northlands grew colder, they had plenty of room to move south in North America. They evolved to better fit the specific the local ecologies from the northern plains of the US to the Valley of Mexico around Mexico City. Since the first discovery of their remains in 1726, they've been given several names: Jefferson's mammoth, the imperial mammoth, and the Columbian mammoths. Some taxonomists have tried to use two or all three to describe stages in their evolution. The current preferred taxonomy is to merge all three into one species. (Dammit! I'm getting all dissertationy.)

Meanwhile, back in Eurasia, rather than moving south and adapting to warmer climates where they would have had to compete with already established proboscideans (elephants), old world steppe mammoths adapted to the gradually cooler conditions of the north, eventually becoming woolly mammoths. In fact, they were a key species in the creation of a unique arctic ecology, the mammoth steppe, Since they went extinct, that territory has all been colonized with Arctic tundra.

Steppe mammoths were the second largest known probiscidean, after the odd looking giant dienotherium. They were tall and long legged with, we assume, some hair. Columbian mammoths were somewhat smaller (coming in at third largest) and, we think, hairer. Woolly mammoths differed quite a bit from it's parents and siblings. Not only were they shorter and stockier, they had multiple specific adaptations to the cold north. Besides hair, they had two layers of wool. Their trunk had a different shape that allowed them to scoop snow, for water, and protected the naked top of the trunk. Most intersting, they had a different blood hemoglobin that bonded oxygen at lower temperatures. They also had something called an anus flap.

Aside from just showing off my knowledge, my point is that the Columbian mammoth is a distinct species easily distinguished from the woolly mammoth. Mastodons, despite some superficial resemblances, aren't even close. Quite a few mastodon relatives might have lived in that area, but, except for the somewhat familiar American mastodon, all of them were extinct by the time mammoths arrived.

Possibly the coolest thing about this discovery is that so many different species have been found. Individually, each of these animals is fairly well known. Taken together, we have a slice of an entire ecology. The owners of the property are being very patient about letting the scientists take their time examining the site. The deserve credit for that. Send those guys a cake.

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