Similarities and differences: understanding homology and analogy (High School level) :
The tetrapod limb
Congratulations! You seem to already be an expert in homologies you've
selected all the homologous limbs. The four limbs you picked out all belong
to tetrapods animals with four legs.
Notice how these tetrapod limbs are similar to one another:
Here you can see the same bones labeled in these different limbs:
- They are all built from many individual bones.
- They are all spin-offs of the same basic bone layout: one long bone attached
to two other long bones.
Even though these limbs are similar to one another, the animals they belong to
are quite different from one another. What animals possess these homologous limbs?