The bones in the front limbs of many mammals are similar in their structure and arrangement. What term is used to describe physical similarities between related species that indicates a common ancestry?

The answer is homologous structures.

Homologous structures are similar structures shared by different species. For example, the anatomy of the front limbs of amphibians, lizards, and mammals, support the idea that these groups have a common ancestor. But since these groups are different enough to be separated into different classes, it can be concluded that they evolved from the common ancestor.