A team of scientists from Yale University has discovered in Iowa (USA) the fossil remains of a new species of eurypterid or gigantostracean , better known as “sea scorpion” and named Pentecopterus decorahensis . The Pentecopterus lived 460 million years ago in prehistoric seas and its name is due to the fact that its structure and movements have a great similarity to the Penteconteros, the ancient Greek warships that were propelled by 50 rowers.
More closely related to modern spiders, Pentecopterus grew to more than five feet long. Its considerable size under the sea made it one of the most fearsome predators of this time and also the oldest known extinct species of “sea scorpions” so far.
“ The new species is incredibly rare . The shape of the leg, which must have been used for swimming, is unique, as is the shape of its head. It was also very big, ”describes study leader James Lamsdell.
The state of preservation of the fossil is incredible: the exoskeleton was compressed into the rock. “This shows an astonishing amount of detail like the tiny hair marks on the legs,” clarifies Lamsde. In addition, the researchers discovered more than 150 fossil fragments when excavating the upper layer of the Winneshiek sedimentary complex (northeast of Iowa); a 27 meter thick sand shale found in the crater of an ancient meteorite impact, submerged by the river for the most part.
This great variety of fossils has made it possible to detail some parts of the Pentecopterus anatomy with great accuracy: it could measure up to 1.7 meters long , its rear limb included a leg with a large surface and joints that it could use for swimming or digging; the other two extremities would be used to capture prey.
The study has been published in the journal BMC Evolutionary Biology.
