This problem of when the mammoth died should have puzzled the Old World as well as the New and caused us to question the dating of Neanderthal and Cro-Magnon quite as much as Folsom man. Oddly enough, it did nothing of the kind. In Europe the mammoth was accepted as diagnostic of the glacial period. The fact that a Magdalenian man of southern France sketched a mammoth on the wall of a cave proved that the man existed in the Great Ice Age. But in America, if a spear point turned up with the bones of a mammoth, too many anthropologists accepted it as proof that the animal died after the ice fields had melted. The mammoth proved the antiquity of man in Europe; man proved the modernity of the mammoth in America. The only shred of evidence to support such reasoning was the questionable pottery and coal that lay beside the mastodon bones in Ecuador. We should have had more and better proof, and we are beginning to get it. More Radiocarbon Dates for Extinct Mammals Working together, archaeologists, paleontologists, and physicists are providing more and more facts about the great extinction. Archaeologists are supplying artifacts for cultural associations, and animal bones that the paleontologists identify. In radiocarbon laboratories, the physicists are dating the bones and sometimes charcoal from man-made fires. Through the evergrowing list of dates, many early theories are being replaced with factual knowledge. Some of the dates, however, must be taken with a grain of sodium chloride. A single date from a single sample in only one locality is not too trustworthy. The hazards are obvious, yet nevertheless we have a fairly large body of facts. From these, a general impression of the great extinction is beginning to take shape. As anticipated, man and climate are involved in the disappearance of the animals. As for climate, a period of much warmer temperatures followed the end of the last glaciation. This lasted from about 10,000 to 2,600 years ago. Antevs isolates the time of highest heat—the Altithermal—as about 7,000 to 4,000 years ago.[33] This matches fairly closely the last dates for our extinct mammals. Heat and aridity may have driven the larger animals to the more and more limited watercourses where man himself would concentrate. Paul S. Martin has noted that the first large mammals to disappear were those in Alaska and Mexico, and that they were followed by the animals of the Plains toward what must have been the beginning of the hot and dry Altithermal period. Martin believes that the grazing and browsing mammals found refuge in the savannas of Florida.[34]