Animals The Fossil of a Half-Billion-Year-Old, 50-Legged Arthropod Was Found in Canada The 4-inch-long creature, named Tokummia katalepsis, was discovered in sedimentary rock in Kootenay National Park in British Columbia.

A 508-million-year-old critter — one that looks like a weird lobster with 50 legs, two claws and a tent-like shell — is the oldest known arthropod with mandibles on record, a new study finds. Arthropods are a group of invertebrates that includes spiders, insects and crustaceans. Many arthropods, including flies, ants, crayfish and centipedes, have mandibles — appendages that can grasp, crush and cut food. But until now, it wasn't clear when this unique feature evolved. Now, researchers can say that mandibles developed by at least the late Cambrian (the Cambrian period, known for its famous explosion of new, diverse life, lasted from about 543 million to 490 million years ago). [See Images of the First Known Arthropod to Sport Mandibles] Researchers discovered the first of the 21 fossil specimens in sedimentary rock in Kootenay National Park, in British Columbia, Canada, in 2012. They named the roughly 4-inch-long (10 centimeters) creature Tokummia katalepsis, honoring Tokumm Creek, which runs along the northern part of the park through Marble Canyon, where they found the fossils. The species name, katalepsis, is derived from the Greek word for "seizing."