How big would an asteroid need to be in order to wipe out all land animals?

No.13069662 ViewReplyOriginalReport
I know Cretaceous asteroid was pretty big (10-15km), but that thing failed to wipe out the Dinosaurs. It's too small.

I need something that can kill off large mammals, birds and reptiles, but also small burrowing animals like rodents.

How big would this hypothetical rock need to be? 200km? 400km?