Fossils tell us that squids were around by the Early Jurassic. Like jet boats, they challenged the fastest animals around. But they didn t just conquer the shallows. Though hard shells offer protection from predators, they may not withstand the extreme pressures of the deep sea. Without a rigid shell, squids can dive deep into the inky depths of the sea.
Squids have enormous eyes.
Indeed, the largest eyes of any living creature belong to the giant squid. With such enormous eyes, these sea monsters may watch for glimpses of one animal that pursues them into the abyss the sperm whale. But Belemnitella americana lived long before there were whales, and it was much smaller than a giant squid. Like most living cephalopods, most belemnites lived in relatively shallow waters along continental shelves. Belemnitella americana lived during the Cretaceous Period, when dinosaurs still stalked the land.