Great Dying of NA Mega FaunaThe disappearance of Mega fauna in NA is typically attributed to expansion of Human activity 13,000 years ago. Ironically, elephants, giraffes, rhinos and hippopotamus continue to thrive in Africa, in spite of the long history of Human habitation on the continent.
The Perigee: Zero Hypothesis suggests catastrophic impact events are implicated in these extinctions. In particular the proposed Saginaw Bay impact and distal ejecta emplacement events may have directly (through strike and ejecta entombment) and indirectly (through environmental changes), precipitated the Megafauna Extinctions during the late Pleistocene. The finds of MegaFauna remains buried under heavy layers of undifferentiated and unstratified soils and gravels are indicative of such ejecta emplacement burials. Similar finds have been found across Siberia. Russian scientist at one time thought that Mastodons were mole-like creatures, since their remains were almost always found intact underground.
The proposed timeline sequence of early Perigee: Zero impacts which struck the Wisconsin glacial shield and precipitated the first meltwater pulse (MWP1) are seen as lasting approximately 400 years, during which time the worldwide sea levels rose significantly. Perigee: Zero events are also seen here as implicated in global climate changes.
When the first humans migrated from Asia to North America 15,000 years ago or more, they confronted an array of big animals more dazzling than that of modern Africa. Mammoths, mastodons, camels, horses and a stately deer called the stag-moose coexisted with giant ground sloths and beavers the size of today's black bears.These plant-eaters were prey for meat-eaters like saber-toothed cats, savage short-faced bears, cheetahs, maned lions and dire wolves, bigger versions of today's wolves. Scores of other large species roamed the continent as well.
“They all vanished about 13,000 years ago in a geological eye blink of perhaps 400 years. The cause of this mass extinction and similar ones elsewhere in the world near the end of the Pleistocene era has been a much debated mystery. “One camp in the debate contends that a rapidly changing climate at the end of the last ice age did in the Pleistocene megafauna, as they are called, by transforming their habitat.
Stevens, William K. 1997. New Suspect in Ancient Extinctions of the Pleistocene Megafauna: Disease. New York Times, 4-29-97
"An opposing camp, pointing out that the extinctions closely followed the animals' first contact with modern humans, holds that the megafauna were essentially hunted to extinction. The hunters' blitzkrieg was made easy, they contend, because the naive victims had no fear of people and were easy prey for prehistoric humans with well-honed spears.”