Scientists announced that the discovery, at a quarry near Prümin Germany, of a claw suggests that the giant sea scorpion, extinct for 250 million years, was a dominant predator.
The size of a large crocodile, the 390-million-year-old sea scorpion was the top predator of its day, slicing up fish and cannibalizing its own kind in coastal swamp waters, fossil experts say.
Jaekelopterus rhenaniae measured some 8.2 feet (2.5 meters) long, scientists estimate, based on the length of its 18-inch (46-centimeter), spiked claw.
The find shows that arthropods—animals such as insects, spiders, and crabs, which have hard external skeletons, jointed limbs, and segmented bodies—once grew much larger than previously thought, said paleobiologist Simon Braddy of the University of Bristol in the United Kingdom.
They believe that unlike scorpions today this creature could not have come out of the water and onto land because its legs would not carry the weight of its body.
The also believe this arthropod was at the top of the food chain, cannibalistic and would have eaten anything smaller than it was.
It is also thought that the reason that insects grew bigger millions of years ago was because of the higher concentration of oxygen in the atmosphere let dragonflies sometimes grow to the size of hawks, and some millipede-like bugs reached some six feet in length, a new study suggests.