American megafaunal extinctions at the end of the by Gary Haynes

By Gary Haynes

The quantity comprises summaries of evidence, theories, and unsolved difficulties touching on the unexplained extinction of dozens of genera of more often than not huge terrestrial mammals, which happened ca. 13,000 calendar years in the past in North the US and approximately 1,000 years later in South the United States. one other both mysterious wave of extinctions affected huge Caribbean islands round 5,000 years in the past. The coupling of those extinctions with the earliest visual appeal of people has resulted in the recommendation that foraging people are responsible, even if significant climatic shifts have been additionally occurring within the Americas in the course of the various extinctions. The final released quantity with related (but now not exact) topics -- Extinctions in close to Time -- seemed in 1999; because then loads of cutting edge, interesting new examine has been performed yet has now not but been compiled and summarized. diversified chapters during this quantity supply in-depth resumés of the chronology of the extinctions in North and South the USA, the potential insights into animal ecology supplied by way of reports of reliable isotopes and anatomical/physiological features reminiscent of progress increments in giant and mastodont tusks, the clues from taphonomic learn approximately large-mammal biology, the functions of relationship the right way to the extinctions debate, and archeological controversies pertaining to human looking of huge mammals.

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2006] and in the central Appalachians [Kneller and Peteet, 1999]). The Younger Dryas lasted for 1,300 years. This was a time of very cold winters but relatively warm summers. With the ice-free corridor open, perhaps this was the first time that the “Arctic express” cold fronts from Siberia hit the Plains (Yu and Wright, 2001). In any case, judging from Greenland ice, the Younger Dryas was no colder than previous stadials, none of which had caused widespread extinction of large North American mammals.

Clearly, Caribbean sloths survived long after the onset of Holocene climate, and their demise correlates roughly with human arrival. However, the temporal overlap of first humans and last sloths seems to have been relatively long (over a thousand years) compared to that seen on the American continents (see MacPhee, Chapter 9). Conclusion Both an accumulating corpus of radiocarbon dates and a variety of stratigraphic data indicate that most of the megafauna of North America went extinct within 500 years of the arrival of Paleoindian hunters – by 12,700 cal bp.

No such dramatic change can be postulated for South America. At present, it has not been demonstrated that the gradual climate change there reached a critical threshold at 12,500 cal bp that would have caused the disappearance of 37 or more mammalian genera within a few centuries. The ubiquity and synchrony of sudden deaths argues for a single cause, and the obvious new ecological factor that transcended all zones was a rapidly expanding human population. 2. Sudden Deaths: The Chronology of Terminal Pleistocene Megafaunal Extinction For now, only about half of the extinct Pleistocene genera in North America can be demonstrated to have survived down to the time of sudden death.

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