“The chimps and all the other forest loving animals that lived with them became extinct, locally, because of this change.” And second, these environments have changed dramatically in the last half million years,” Jablonski said. First, chimps were once more widely distributed. Based on the presence of these animals, researchers determined the area used to be much different. They also found fossilized remains of fish, hippopotami, antelopes, cane rats, buffalos, monkeys and other moisture-loving animals. They’re triangular and very thick – much thicker than the same tooth in a human.” “The incisor teeth at the front of the jaw are also very distinctive. “Chimp teeth are actually very distinctive, because compared to human teeth, molars for instance, they have very, very low crowns,” Jablonski said. Although these teeth were mixed in with fossils of many other animals, they quite definitely belonged to a chimp. Researchers dug up three teeth-two incisors and one molar. But in that time, the lake shore that the chimps and other animals called home has dried up, creating conditions good for preserving fossils. Half a million years ago, the Rift Valley was likely more moist and wooded than it is today. “All things being equal, you’re more likely to find teeth than anything else.” “Teeth are the part of the body that gets preserved most frequently,” McBrearty said. They’re coated with thick enamel, which protects them from chemical attacks and makes them less desirable for hungry scavengers. Teeth, on the other hand, more frequently survive. One of the more frustrating aspects of paleontology is that full skeletons are very infrequently preserved-especially in jungle environments where soil acidity and scavengers destroy or eat bones that could otherwise become fossils. We need to look for another reason for the evolutionary split.” This shows it certainly wasn’t true half a million years ago, and may not have been true before that. “People have still retained this idea of a split geographic distribution of chimps and humans. “For many years people have used this kind of geographic split in environment as an explanation as an origin of humans and bipedalism,” coauthor Sally McBrearty of the University of Connecticut told LiveScience.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |