Tiny teeth tell the story of two fish species’ rapid evolution

Friday, November 16, 2018 - 15:10 in Paleontology & Archaeology

Elizabeth Sibert is rewriting the story of how the asteroid impact that killed off the dinosaurs affected fish, and she’s doing it one tooth at a time. Based on close examination of thousands of fossilized fish teeth, Sibert, a Junior Fellow of the Harvard Society of Fellows, found that while the impact did cause some fish species to die off, it also set the stage for two periods of rapid evolution among marine life. Of the 48 types of fish teeth that were found before the extinction, Sibert and colleagues discovered that just two were wiped out, an extinction rate far below that experienced by other creatures during the same period. Those two, however, were the dominant species, as they made up nearly half of all teeth found before the extinction, so in their absence other types quickly evolved to fill that void. “I think fish are one of the ultimate survivors,” Sibert...

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