Hallucigenia's head

Abstract

Therefore, Cambrian fossils are particularly important for understanding the origin and early evolution of major animal groups. In this issue, Smith and Caron2 (page 75) redescribe one of the most celebrated Cambrian animals, Hallucigenia sparsa, and document several new features of this species, including its pharyngeal teeth and circumoral elements, which are suggested to be two of the few morphological characters uniting all groups within the Ecdysozoa.