Chapter 26.2, Problem 1BC

Summary Introduction

To determine:

If three layers in the Bilateriaa shared derived character or a shared primitive character.

Introduction:

Phylogenetics can be described as the study of the evolutionary history of an organism and its relationship with other biological organisms. Systematics is the science of classification and study of organisms regarding their natural relationships.

With respect to phylogenetics and systematics, a shared primitive character is that character that is shared by members of a clade, that originated in an ancestor that is not a member of that clade. Shared derived character is that character that has an evolutionary uniqueness that is distinctive to a clade, it is not inherited from ancestors.