The radiation of animals across the Ediacaran-Cambrian transition is one of the most transformational events in Earth history, radically changing Earth’s surface environments. However, while fossils from the Cambrian are readily recognised as belonging to extant groups, those from the late Ediacaran Period show distinctive forms with no counterparts among living species. Although these Ediacaran fossils are often held to represent the antecedents to modern animal groups, their strange anatomies have meant that, for the most part, they have been eschewed from the debate and their unique insight left unrealised. My work combines novel morphogenetic data and phylogenetic systematic studies to show that these unique fossils are animals to the exclusion of alternatives and likely occupy a critical position in the tree of animal life. This conclusion enables me to integrate Ediacaran macrofossils into debates concerning the ancestors of major animal lineages and the mode of early animal evolution, for example, in the influence of the evolving regulatory genome on the evolution of animal complexity.