Evidence suggest six mass extinctions.

[Mycroft]

New evidence from fossils suggests that there has been six mass extinctions, not five.

New Fossil Evidence Suggests There Have Been 6 Mass Extinctions, Not 5 | IFLScience

 

[Ouroboros]

Dang. Then we're in the 7th, not the 6th, right now.

 

[shawn001]

and this is something we should be thinking about now.

"Additionally, an apparent widespread lack of carbonates across higher latitudes could also indicate a role for ocean acidification."