Published in Live Science, March 11, 2015
By Laura Geggel, Staff Writer
A remarkably well-preserved fossil of a 480-million-year-old sea monster is helping researchers understand the evolution of arthropods. The creature, an anomalocaridid, has not one but two sets of legs on each of its body segments, showing that it’s an ancestor of modern-day arthropods, which include arachnids, insects and crustaceans.
Here’s an illustration of the anomalocaridid (Aegirocassis benmoulae), a giant filter feeder that ate plankton and lived in the Early Ordovician period about 480 million years ago. The animal measured about 7 feet (2 meters) long, and is one of the largest arthropods that ever lived.
Despite its size, A. benmoulae was a gentle giant, said John Paterson, an associate professor of paleontology at the University of New England in Australia, who was not involved in the study.
“Its feeding appendages werebuilt for filtering plankton, not grasping prey,” he said. “This is in contrast to olderanomalocaridid species, some of which are interpreted to be the apex predators of their time.”
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