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"Go Fish" -- The Discovery Files

The Discovery Files
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A new study from the University of Chicago reports that a mass extinction of fish 360 million years ago hit the reset button on life on Earth, setting the stage for modern vertebrate biodiversity.

Credit: NSF/Karson Productions

Audio Transcript:

Hitting the Evolutionary (Sound effect: rewind sound) 'Reset' Button.

I'm Bob Karson with the discovery files -- new advances in science and engineering from the National Science Foundation.

University of Chicago scientists are 'fishing' for the origins of all vertebrates, including humans. Their new study pinpoints a specific time on earth when evolution seemed to completely change direction. Later than previously thought -- lucky for us, it was in our favor.

About 360 million years ago, there was a mass-extinction -- whatever the reason, it killed off most species almost completely. Prior to this event, (Sound effect: sea sound) life in the seas was dominated by fish you'd hardly recognize -- like big ol' armored placoderms. In the minority were familiar ancestors to modern fish -- and the first tetrapods, just starting to make their way out of the water to walk on land. (Sound effect: character voice: "hey...I'm walkin' here...")

According to the study, it was during the 15-million year period afterward that something unusual happened: eventually, some of the fish that were in the majority failed to come back -- while some of our vertebrate ancestors not only recovered but flourished to become the predominant life forms, setting the stage for modern biodiversity by changing the whole cast of players.

This more accurate assessment of the critical shift in earth's evolution is possible because of recent advances in the filling of the fossil record. Had this change not occurred, you'd be listening not to me but to a giant talking armored placoderm.

"The Discovery Files" covers projects funded by the government's National Science Foundation. Federally sponsored research -- brought to you, by you! Learn more at or on our podcast.

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