![]() They brought dogs with them that made them better hunters. They competed with the big carnivores for game. They burned forests and grasslands that big mammals used. ![]() But humans did other things besides hunting that hastened the disappearance of big mammals. ![]() "Certainly humans exploit large game," she says, "probably because they are tasty"-and because a bigger animal makes for a bigger meal. She says it basically came down to hunger. Looking back over the most recent 125,000 years of the fossil record, Smith found that when humans arrived someplace, the rate of extinction for big mammals rose. But it did when humans were involved," Smith found. "Taken as a whole, over 65 million years, being large did not increase mammals' extinction risk. And then lots of really cool predators, like Arctodus, the short faced bear." The short-faced bear stood 11 feet tall, about the shoulder height of some species of ancient camel.īeing big was just as successful as being small, and had some advantages when it came to surviving big predators. Among the giant creatures: "Llamas and camels and sloths and five species of pronghorn actually," she says, "and certainly mammoths. Many of the early mammals went on to get big. ![]() Smith studied fossils going back 65 million years, when dinosaurs died and mammals came into their own. That's the conclusion of a new study of the fossil record by paleo-biologist Felisa Smith of the University of New Mexico. Over the past 125,000 years, the average size of mammals on the Earth has shrunk. The cave bear (Ursus spelaeus) was a species of bear that lived in Europe during the Pleistocene and became extinct at the beginning of the Last Glacial Maximum, about 27,500 years ago. An illustration from 1870 shows Prehistoric men using wooden clubs and stone axe to fend off an attacks by a large cave bear. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |