Question

Which of the following sets of bones are homologous between humans and Dimetrodon?

a) Human arm bones and Dimetrodon tail bones
b) Human leg bones and Dimetrodon spine bones
c) Human skull bones and Dimetrodon jaw bones
d) Human rib bones and Dimetrodon limb bones

Answer 1

The bones that are homologous between humans and Dimetrodon would be the limb bones, so option (d) Human rib bones and Dimetrodon limb bones is the correct answer since both can be traced back to a common tetrapod ancestor.

Step-by-step explanation:

The bones that are homologous between humans and Dimetrodon would be the bones that are part of equivalent structures with a common evolutionary origin, even if their functions may differ. Specifically, the upper forelimbs in various animals have fairly similar structures across different species, such as between the arms of humans and the forelimbs of cats. This similarity extends back to prehistoric tetrapods and the ancestors of mammals like Dimetrodon. While the Dimetrodon is not a direct ancestor of humans, they share a more distant common ancestor with mammals. Therefore, the set of bones most likely to be homologous between humans and Dimetrodon are their limb bones.

In answer to the student's question, option (d) Human rib bones and Dimetrodon limb bones would be the correct choice, as the limb bones of Dimetrodon are equivalent to the bones in the human arm, both of which can be traced back to a common ancestor. The human arm (e.g., humerus, radius, ulna) as well as Dimetrodon's forelimb bones share a homologous evolutionary background, stemming from early tetrapod structures.