The Wray study concluded that the common ancestor of the animal forms lived 1.2 billion years ago, implying that the Cambrian animals took some 700 million years to evolve from this “deep-divergence” point before first appearing in the fossil record. Wray and his colleagues attempted to explain the absence of fossil ancestral forms during this period of time by postulating that Precambrian ancestors existed in exclusively soft-bodied forms, rendering their preservation unlikely.
