This "latest extinction" is not referring to the dinosaurs or the "global flood". It refers to the extinction of the megafauna that populated the northern hemisphere at the end of the Pleistocene epoch (this happened about 12,000 - 13,000 years ago).
There are the climate change folks, there are the over-kill folks and now there are the asteroid-impact folks.
The asteroid impact has been a big splash in the extinction literature lately but it is really just a big flash-in-the-pan... (yuk yuk)
In all likelihood it is a combination of rapid climate change coupled with the introduction of humans in the new world.
Initial studies that pointed to evidence of an asteroid impact with subsequent widespread fires all over the northern hemisphere have been found to be severely lacking.
The whole "controversy" was very interesting.
We had a neat event at our university called the "Scopes Mammoth Trial" where we weighed the evidence for and against the asteroid impact theory. Three or four of the original scientists that discovered the stratigraphic layer that is claimed to house the evidence for the asteroid impact were present. They all gave the asteroid impact theory a big "ppphhhlllbtbtbt!" and a thumbs down.