The size and shape of the vertebrate skull can reveal a great dea...

Question

The size and shape of the vertebrate skull can reveal a great deal about an animal's lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don't. Where did ear bones come from?

Accepted Answer

Welcome back. Let's look at our next question. White threads of evidence from fossils and developing embryos suggests that the mammal's ear bones were once jawbones if they truly were. What is the advantage of having the jawbones and ear bones separated like the modern mammals have? Well let's look through our answer choices Choice A. Says to developed specialized functions. Well the separation of ear and jaw bones gives mammals finally tuned hearing and the extra bones in the jaw create a more flexible jaw which is good for chewing. So when choi sae says to develop specialized functions, that seems like a pretty good candidate for a correct answer because there's an advantage to the mammals from having these separated and giving them better hearing and more flexible jaws. But let's just check. I'm gonna mark this here. But before we select that as a correct answer, it's probably a good idea to look at the others and make sure nothing seems like a better explanation. Choice B. Says to conserve a lot of energy. Well there's no reason why this separation would conserve any particular amount of energy so that isn't a better answer than a choice C. Says to give mammals the ability to maintain balance. Well that's not a result of this separation here. So that wouldn't be a better answer. Choice D says to become more attractive. Well as far as we know there's no benefit to mate selection or anything such as that by having this separate uh bones no reason to say that would make them more attractive to mates. So definitely not a better answer than a. So the advantage of having job bones in their bones separated would be to develop specialized functions. Choice A. See you in the next video.

Watch next