The world is losing monsters left and right. First the T-Rex went vegetarian and turned into a bird, and now it looks like giant, ancient sea scorpions might have eaten only greens as well.
Up until recently, it was thought that every time a person ordered lobster off a menu at a seafood restaurant, it represented a huge upset in the relationship between predator and prey. Sure, right now soft, fleshy animals don't have much to fear from invertebrates, but for millions of years the claw was very much on the other arm. Back in the Paleozoic era, pterygotid eurypterids or sea scorpions were thought to be a top predator. Basically eight-foot-long lobsters with armor defending their flesh, claws defending their armor, and spines defending their claws, these beasts were thought to be top predators.
It turns out, that armor and those claws were not as tough as they appeared. The sea scorpions claws were so weak and had such limited mobility that they couldn't break through the shell of a mid-sized horseshoe crab. If they even tried to break tougher objects, the claws themselves would break apart.
(Pictured: A mid-sized horseshoe crab smiling defiantly at a giant, slavering sea scorpion [off camera].)
Instead of cracking shells or capturing large, muscular prey, it's now thought that these giants picked their way along the floor of the ocean, grabbing small objects and feeding on them. The objects could be small fish or invertebrates living on the sea floor, but could just as easily be carrion or even vegetable matter. One discovery demoted pterygotid eurypterids from top predators to kelp-eaters.
So if you're sent back in time, don't worry about the motorcycle-sized lobsters eating you. Instead, lure them in with some seaweed, drag them onto land, and have the lobster cook-off to end all lobster cook-offs.
Via Science Blog.