The team of scientists found the Yilingia spiciformis, which translates to "spiky Yiling bug," preserved in layers of rock near the Chinese city of Yiling. It resembled a millipede up to 10 inches in length, broken into 50 segments across its short body. The spiky Yiling bug is one of the earliest bilaterians—that is, animals with bilateral symmetry, like humans—with segmented bodies and movement. They laid the groundwork for larger animals to move, think and impact their environment, he said. Scientists always assumed segmented bilaterians evolved sometime between 635 million and 539 million years ago, but they'd never found evidence...