Celebrating a Century of Fossil Finds In the La Brea Tar Pits 93
An anonymous reader writes "A century ago on Monday, the predecessor to the Natural History Museum of Los Angeles County began a two-year project to uncover the Ice Age creatures that became trapped in the La Brea Tar Pits. 'Digs over the years have unearthed bones of mammoths, mastodons, saber-toothed cats, dire wolves and other unsuspecting Ice Age creatures that became trapped in ponds of sticky asphalt. But it's the smaller discoveries — plants, insects and rodents — in recent years that are shaping scientists' views of life in the region 11,000 to 50,000 years ago.'"
It's an excellent musem (Score:5, Informative)
If you're ever in Los Angeles, you should visit the museum. The specimens are only about 50,000 years old and they were almost perfectly preserved by falling into the tar pits. Their skeletons are remarkably intact. It's not like dinosaur fossils which are extensively reconstructed. Every last little bone and joint is original and in excellent condition.
There are all sorts of massive mammals like sabre-tooth tigers, giant sloths, giant camels which apparently roamed North America until fairly recently, etc.
It's a worthwhile excursion if you happen to be in LA.
Re:Why bother? (Score:5, Informative)
They have dug up millions of bones - to what purpose? One would think that by now they have enough to fill a large warehouse that no-one will ever look at again, except may another archeologist digging up Los Angeles and wondering how all these ancient bones became so mixed up in a big jumble with traces of rust in the clay, around the big altar of the 21st century religious complex known as 'the museum'...
I used to wonder about that too until a paleontologist explained to me that digging up large amounts of bones, even from mundane species like duckbilled dinosaurs, can yield all sorts of data bout things like: what was the extent of variations in skeletal morphology? what did these critters die of, i.e. diseases, who ate them? how did different predators kill duckbills? (which tell you something about a whole range of predators that you have practically no other way of finding out except maybe uber-rare fossilized footprints) .... the list goes on. You can also infer things about social behavior by digging up large collections of bones from a single species, you can get clues from them about how environmental factors affected population size and which environmental extremes limited a species' habitat. Another example is archaic humans whose skeletal remains are a couple of steps up from dragon's teeth on the rarity scale. The grand to total of the Neanderthal remains is IIRC about 100 (mostly incomplete) skeletons which is an unusually large sample size. It's also wroth noting that Neanderthals existed for c.a 350.000 years so that's one skeleton per 35.000 years. The skeletal remains of most older hominid species are much, much more rare. In the last few decades archaic humans have been sub-divided into a large number of subspecies based on differences in skeletal morphology and often a species classification is based on a one or two incomplete skeletons. Recently a unusually large cache of Archaic human bones was found at Dmanisi in Georgia. The morphological differences between the different individuals of that population were found to be about the same as those found in modern humans. Just for example, the Dmanisi finds included an individual whose brain size was half that of most of his contemporaries so one can conclude that brain size is no conclusive indicator of how primitive an individual is. Its the way the brain works that is important not so much the brain size. This find in Dmanisi has led to the realization that a whole group of Archaic human 'variants' including, Homo habilis, Homo rudolfensis, Homo gautengensis, Homo ergaster and Homo erectus were probably the same species and that they may have been been erroneously over-divided into subspecies by scientist reading far too much into variations in skeletal morphology. This is not to say those scientists made a mistake, they just did not have the broad collection of bones available that they needed to establish extremes in morphological variation and drew what conclusions they could based on the evidence available. Thats how science works: procure evidence, examine it, draw conclusions, create a theory, get new evidence, examine it, draw conclusions, revise your theory. It's also what irritates the piss out of religionists who like to have a single never changing doctrine, scientists keep changing their minds.
Re:Why bother? (Score:4, Informative)
Great post, but shouldn't it be one skeleton per 3.500 years? (350.000 / 100)
Yeah (red faced) it should be. But that's still an amazingly low number of specimens for the best documented archaic human species we know of. For a very crude estimate (and I hope I get my math right this time) If we assume the average Neanderthal population world wide over those 350.000 years was 50.000 people, a generation is 25 years and there are three generations alive at the same time you get 50.000/3 ~ 16600 new Neanderthals each generation, so over 350.000 years you have (350.000/25) * 16600 = 231 million Neanderthals that ever lived and we have a sample of 100. Those numbers are crude but they still give you a rough idea of how tiny the sample size is since hominids were never anywhere nears as common in the ecosystem as, say bison or caribou.