Friday, December 5, 2008

BONC #2: The bat with some answers

Barnyard of Old New Critters (BONC) #2

Ok, kids, tell me what you know about bats. Yes, they're mammals, good. No, they aren't really vampires. Yes, they fly really well. And how do they fly so well? Yes, they have superfantastic EARS!

Ah, the bat's ear. Let's try a simple experiment. You'll need a friend for this. First, close your eyes and sing any song out loud. After a little while, your friend can put his or her hand up a few inches away from your mouth. Can you hear the difference between when the hand is there and when it's not? You just "saw" your friend's hand using only your ears!

That's how bats do it. They squeak with their mouths and then listen with their huge ears to "see" things and avoid crashing into them as they fly. Their ears have a bunch of complicated and special bones that let them do this.

So here's the question. Which came first in bats: being able to fly, or being able to "see" with their ears? Bats started out as land creatures that evolved over millions of years to be able to fly. But when did those special ears come, before or after they could fly? Scientists have been fistfighting over this question for years.

Well, a this newly discovered fossil of a bat that lived 52 million years ago has the answer. This critter had the wings and muscles of a flying creature, but the legs and shape of a land animal. It's called Onychonycteris (I don't know how to say it either), and it's one of the very first bats ever.

And - aha! - Onychonycteris did NOT have those special ear bones. So the answer is: first bats evolved flight, and then they evolved the ability to "see" with their ears.

So here's my next question. If they could fly before they could "see," weren't they crashing into things all the time? Maybe Onychonycteris had really good eyesight instead (they can't tell about its eyes from the fossil.) Or maybe it was just really clumsy. Maybe other animals had to watch out for crazy Onychonycterises always bashing into them. Duck!

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