With only 300 - 400 northern right whales in existence we could very well witness this magnificent species become extinct in our lifetime and your support will be critical to their survival. (georgiaaquarium.org)
In each case, more than half of plant and animal species became extinct. (theguardian.com)
I have read that some scientists think dinosaurs became extinct because their climate changed - it got too cold, and again, no humans were around then. (crunchydomesticgoddess.com)