I still haven't heard what either of their definitions of common descent is. Is it your belief that they are considering it to mean that all living things descend from single celled organisms of which we don't know how they came about?
This typical Darwinian definition seems to fly in the face of Behe's criticisms of the mechanisms being presented by Neo-Darwinists.
The transition from single-celled to multi-celled is lost, but there are many living species that are intermediate, colonies of independent cells.
We, and every other living thing, pass through a single cell phase.