By Susan Milius
Fossils of an ancient “walking cactus” suggest how ancestors of today’s lobsters, insects, spiders and related groups went from squishy to spiky.
Dating back about 520 million years, the fossilized prickly creature is not a plant but a thumb-sized, wormlike animal with 10 pairs of long, sturdy legs, says Jianni Liu of Northwest University in Xi’an, China. Discovered in southwestern China, it probably scuttled along the bottom of shallow seas, she says. In the Feb. 24 Nature, she and her colleagues christen the species Diania cactiformis, in honor of its spiky look.
Its armored leggy look surprised Liu when she first saw it. “I fell in love with this strange guy,” she says. “Later when I observed it carefully under the microscope, I realized it was not only a funny one but an important one.”