Chemical clues to the earliest animal fossils

The Ediacara biota are a diverse assemblage of macroscopic body forms that appear in the sedimentary rock record between 570 million and 541 million years ago. First recognized in Namibia and Australia, these remarkable organisms have since been found in Russia, China, Canada, Great Britain, and other regions. Although they immediately preceded the rapid appearance and diversification of animals in the Cambrian (541 million to 485 million years ago), their position within the tree of life has long been a puzzle. Some Ediacaran fossils appear segmented, but most lack obvious characters such as appendages, a mouth, or a gut that might link them to animal clades. On page 1246, Bobrovskiy et al. (1) use biomarkers to confidently assign at least one Ediacaran group, Dickinsonia and related taxa, to the Metazoa (animals).