The link is to the description of an AGU special session that discusses a hypothesis for an impact causing the extinction of the North American megafauna, including mammoths and dwarf mammoths (what I call Mimmoths as a joke and to avoid the oxymoron). It also caused climate change that pushed the earth part way back towards an ice age...at ~13,000 years ago.
I'm only describing what is in the link...Kennett told us all kinds of wild stuff related to his/their hypothesis. I told him where to find one of the "black mats"...which I had been aware of as being unusual in the early 90s. I had a lot of the information then to come up with such a hypothesis, but failed to do it...wrong expertise? Lack of imagination in this case...

The link is called "The last mass extinction impact". This is not counting the current mass extinction which is underway, and seems inevitable.
Chris
Chris

• The last mass extinction impact