This interactive module traces the evolutionary history of birds by comparing the bone structures of a chicken to those of other species.

In this Click & Learn, students explore a simplified evolutionary tree of chickens starting from the last common ancestor of birds and crocodiles, which lived about 250 million years ago. Students compare the bones of a chicken to those of its dinosaur relatives at key nodes of the tree, to pinpoint some of the similarities that suggest that birds are avian dinosaurs.

The accompanying “Worksheet” guides students’ exploration of the Click & Learn.