Some of the extinctions do not make sense.
Try these.
Raptor shape.
The comet theory killed T rex and his fellow raptors. BUT the shape re rvolved in the first great age of mammals at the Terra Bird. These flightless predatory birds were bigger than a moa and hundted as T Rex had.
But in the next great mammal age virtually all of the top predators went from hunting on two legs to hunting on four. All of them.
In the age of the dinos the only top predators who hunted on four legs were the crocs. What happend that all the two legged predators died out.?????????????
Speaking of crocs
Why did Ambulesitus go extinct.? This creature was the link between wolf an whale. It was a mammal but it was the size and shape of a croc and hunted the same way, Ambush predator.
In tropical climates the crocs may well have out competed them. But not in the temperate or polar areas. Why didn't some of them survive while some others went on to evolve the modern whale shape.????????
Good thinking folks.