fossils

fossils

Fossils Reveal Oldest Known Human-Sized 'Sea Scorpion'

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A monstrous sea scorpion measuring six-feet-long that lived 467 million years ago has been discovered. The creature was one of the most powerful ocean predators of its time, with a 'helmet' shielding its head and large grasping limbs for trapping prey. Scientists have named the beast Pentecopterus decorahensis, after the "penteconter"- an ancient Greek ship rowed by 50 oarsmen that saw service in the Trojan War. Although they look like relatives of lobsters or crabs, sea scorpions, or "eurypterids", were in fact the ancestors of modern spiders. Lead researcher Dr James Lamsdell, from Yale University in the US, said: "The new species is incredibly bizarre. The shape of the paddle - the leg which it would use to swim - is unique, as is the shape of the head. It's also big - over a meter-and-a-half long! "Perhaps most surprising is the fantastic way it is preserved. The exoskeleton is compressed on the rock but can be peeled off and studied under a microscope. This shows an amazing amount of detail, such as the patterns of small hairs on the legs. The creature, described in the journal BMC Evolutionary Biology, was identified from more than 150 fossil fragments excavated from Winneshiek Shale sedimentary rocks in north-east Iowa, US. Some of the animal's body segments suggest a total length of up to 1.7 metres (5.57 feet), making it the largest known eurypterid from its era. It is also 10 million years older than any other sea scorpion discovered to date. Exceptional preservation of the exoskeleton has allowed scientists to interpret the role of fines structures such as scales, follicles and stiff bristles. During the Ordovician period, when Pentecopterus was alive, invertebrates ruled the oceans and the first animals were only just starting to colonise the land. Early fish at this time grew no longer than about 12 inches and were without a jaw - making them no match for a giant sea scorpion.