Cladistic analysis is a method used to determine an organism’s family tree. The older system of classification, developed by Carolus Linnaeus (Carl von Linné, 1707–1778) in the eighteenth century, categorizes plants and animals by organisms’ overall similar characteristics. Cladistic analysis uses specific characteristics, such as wrist bones, and relates them to previous and following generations, thus tracing the evolution of these structures. The more characteristics previous and following generations share, the more likely they are related. (A cladogram represents a diagram of all the clades, or groups of organisms.)

Cladistic analysis is not easy. Scientists must study the minute details of early animal fossils, noting the tiniest differences in bones and joints. Each different characteristic is assigned a code and added to a computer database. The computer then sorts the information, producing what looks like a “family tree,” linking together past and modern animals by these detailed characteristics.