SSS 2008-09-22

（单词翻译）

This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute.

Fingers are pretty nifty. They let you to grab a latte, type on a keyboard, even pull up your pants. But did you ever wonder: where do fingers come from? In the 1990s, scientists gave this problem a lot of thought. And they concluded that fingers were pretty much invented by the first tetrapods: that is, critters with four limbs. One reason they thought that is because a fossilized skeleton of an ancient fish didn’t appear to have any fingers. Or at least any distinct digits² in its pectoral fin¹. But tetrapods, which evolved from fish, did.

Now scientists writing in the September 21st online issue of Nature say that that thinking was…a little fishy³. Because they’ve unearthed⁴ evidence that suggests that that ancient fish did indeed have fingers in its fins⁵. The researchers did a CT scan on a specimen⁶ about 380 million years old. And they found that the fish’s right fin, which was unusually well-preserved, does appear to have digitlike bones. The reason other researchers previously⁷ missed them, they think, is because in their samples the fingers were hidden behind marks left by the fish’s scales. So fish, too, seem to have incipient⁸ fingers. A finding we give two thumbs up.

Thanks for the minute for Scientific American's 60-Second Science. I'm Karen Hopkin.