when the asteroid hit almost all large life on earth was killed or died as a result. dinosaurs with teeth couldn't find enough prey to feed themselves and starved. small dinosaurs with more beak-like mouths were able to survive by eating seeds and nuts. life in the water was much less effected, and crocodiles/alligators especially can go a long time between meals anyways. some crocodiles can go years without eating so if they just had a massive meal before the impact they were ok.
United States