Animation Description
In the graphic that accompanies this multiple choice question, images of seven animals, shark, tuna, frog, human, hare, caiman, and parrot, are connected by a branching evolutionary tree beneath them. An arrow shows that time progresses in the upwards direction on the tree. On the tree proceeding upwards, a horizontal line on the root marked "vertebrae" indicates that vertebrae evolved in the common ancestor of all the animals on the tree. Then the branch leading to the shark splits off to the left. On the other branch (which leads to the remaining animals), "bony skeleton" evolved. Then the branch leading to the tuna splits off to the left. On the other branch (which leads to the remaining animals), "four limbs" evolved. Then the branch leading to the frog splits off to the left. On the other branch (which leads to the remaining animals), "amniotic egg" evolved. Then a branch splits off to the left that itself splits into two, leading to the human and hare. At the base of this branch, "hair" evolved. The last branch, which extends up and to the right splits into the caiman and parrot branches. At the base of this branch, "two skull openings" evolved. At the top of the diagram, the entire group of animals is bracketed and labeled "vertebrates." In addition, the frog, human, hair, caiman, and parrot are bracketed and labeled "tetrapods." When option "c) amniotic egg" is clicked, the branches of the tree leading from the "amniotic egg" trait up to the human, hair, caiman, and parrot branches are highlighted. This group of organisms is bracketed and labeled "amniotes." When any other option is clicked, the reader is instructed to "try again."
Animation Text
Panel 1
Which feature do humans, hares, caimans, and parrots share that the other three lineages did not inherit?
a) bony skeleton
b) hair
c) amniotic egg
Panel 2
Oops. A bony skeleton is shared by more than just these animals. Look for the feature near the point of common ancestry. Try again.
Panel 3
Oops. Hair is only shared by humans and hares. Look for the feature where all four animals share a common ancestor. Try again.
Panel 4
Great! They are all amniotes. Let's look at the next feature.