The branch of systematics in which evolutionary relationships are established by studying fossils of ancestors of closely related animals is called [[1]] systematics.

The branch of systematics in which evolutionary relationships are established by studying fossils of ancestors of closely related animals is called evolutionary systematics.

Systematics is related to the classification systems and nomenclature of organisms. It involves studies of the distinctive characteristics of species and finding out how they are related to other species through time. 

Evolutionary systematics is a way of determining the natural relationships among closely related organisms. It is the oldest of the three approaches to systematics and is thus called the traditional approach.