A 580-million-year-old fossil suggests that evolution of bilateral symmetry may be simpler than previously thought, Nature reports. The fossil, an eight-armed swirl named Eoandromeda after the galaxy ...

A new study bolsters the idea that the first animals were surprisingly complex, perhaps equipped with muscles and a nervous system. By Carl Zimmer One of the greatest transformations in the history of ...

700 million years ago, a remarkable creature emerged for the first time. Though it may not have been much to look at by today’s standards, the animal had a front and a back, a top and a bottom. This ...

Deep, deep in geologic time, some 600 million or 700 million years ago, the very first animals evolved on Earth. Their closest relatives that still live today include sponges, sea anemones and comb ...