The earliest known primitive chordate is Pikaia gracilens ... (a rodlike primitive backbone), a significant step in the evolution of vertebrates. Cambrian sediments found in Canada, Greenland ...

Name the type of modification of timing of developmental events described for human evolution. Heterochrony or, more specifically, neoteny. In chordate evolution, ancestral tunicate-like form lost ...

Amphioxus is the most basal extant chordate and is thought to closely resemble the invertebrate ancestor of ... we aim to reconstruct the genetic and developmental changes underlying the earliest ...