The book is designed to address fundamental "big questions" about the origins and relationships of multicellular animals (metazoans). Key contributions include:
Published in 2009 by Oxford University Press, it serves as a major synthesis of three traditionally separate fields: , molecular systematics , and developmental biology (evo-devo). Core Themes and Utility
: Rather than relying solely on genes, it emphasizes using the fossil record to date molecular trees and interpret the evolution of body plans.
