If the most significant cause was an extraterrestrial object, then the smaller animals would have been more likely to be able to hide and be protected from the effects. I think that this is why the reptiles which survived the great dinosaur extinction event were snakes, turtles, crocodiles and others which lived in the water or underground; also, of course, our small mammalian ancestors.
Regarding a comment from SC, I was referring to underwater structures, not underwater wrecked shipping.
What I replied was, the underwater structures won’t be looked for until academic thinking gets comfortable with PreColumbian voyagers and starts to examine ancient wrecks, like the amphorae-laden Roman- or Greek-era wreck found decades ago off Brazil.