Causes of the Quartenary megafauna extinctions are a popular subject to talk about.
The main hypotheses are that the extinctions were caused by climate change, human hunting, or both.
A new paper, looking at Patagonia, and conducting genetic and radiocarbon data analysis of megafauna bones, suggests the combination of the two.
Megafauna across the Americas mysteriously disappear from the fossil record toward the end of the last ice age. Scientists have long debated what may have happened and largely point to two possible culprits.
The timing of that extinction seems to coincide with two major events: the peopling of the Americas and the end of the last ice age. So did humans hunt the big animals to extinction or did the changing climate do them in?
Perhaps the two were partners in crime, Dr. Metcalf and her colleagues suggest in a new paper published Friday in the journal Science Advances.
Ice Age mystery: What killed off the mastodons, mammoths, and giant sloths?, Eva Botkin-Kowacki, Christian Science Monitor
With different patterns of climate change in North and South America, megafauna extinction coincided with both human presence and warming in both places.
The increased resolution provided by the Patagonian material reveals that the sequence of climate and extinction events in North and South America were temporally inverted, but in both cases, megafaunal extinctions did not occur until human presence and climate warming coincided.
Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation, Metcalf et al, Science Advances
Having recently looked at non-tree views of evolution, I am fond of this figure from the paper. The authors have decided that branching phylogenies are most helpful for camelids and jaguars, but a network graph is best for pumas.