Q14 - The common ancestors of Australian

[mcrittell]

I've having trouble visualizing how D resolves the paradox in this passage.

Tree Land
|_________|
.......|
.......|
Common Ancestor

Does D suggest the following?:

Tree
|
|
Land (Common Ancestor)

[noah]

Strange one (and I think anything about kangaroos is funny).

The paradox is this: modern tree kangaroos don't have grippers (I'll use this for the grasping tail and the opposable thumbs). We'd expect they would have them, especially when the ancestor of this kangaroo did. In other words, why would they lose their grippers?

We know that land kangaroos did, but that make sense, since they don't need grippers.

(D) resolves this by putting an intermediate ancestor into the family tree. Now it's common ancestor (with gripper) --> common ancestor (without gripper") --> tree kangaroo

(A) might be tempting, but this is just information about how tree kangaroos operate - it doesn't tell us why they might not have grippers. Actually, the reason they have to back down slowly is probably because they lost their grippers!

(B) is about size - we don't know what effect that has on anything.

(C) is about length and flexibility - what effect do those attributes have?

(E) is similar to (C) and (B). What effects do scrawny legs and slowness have?

I hope that clears it up.