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This next story is about a strange fossil found in Antarctica. As NPR's Nell Greenfieldboyce reports, scientists were astounded when they finally realized what it was.
NELL GREENFIELDBOYCE, BYLINE: A couple of years ago, a paleontologist named Julia Clarke was visiting a colleague at a natural history museum in Chile. The two were chatting about fossils.
JULIA CLARKE: So then he said hey, you know, you should see this thing we collected. And he said, we call it the thing.
GREENFIELDBOYCE: The thing wasn't a bone, but what was it exactly? No one knew. It was about the same size and shape as a deflated football.
CLARKE: I just take one look at this thing and it's the thing. And I was like, that is a giant, deflated egg.
GREENFIELDBOYCE: A soft-shelled egg, to be precise. The biggest one ever found. Now, today some snakes and turtles and lizards lay eggs with soft, flexible shells, but they're rare to find in the fossil record.
CLARKE: We did not realize that soft-shelled eggs could even get this big.
GREENFIELDBOYCE: Clarke, who works at the University of Texas at Austin, collaborated with her colleague from Chile and other researchers to study this egg. In the journal "Nature," they say it was likely laid by a mosasaur: a 20-foot-long marine lizard that lived some 66 million years ago. The enormous egg thrilled paleobiologists like Jasmina Wiemann of Yale University.
JASMINA WIEMANN: We just thought, oh, this is fantastic.
GREENFIELDBOYCE: That's because she was making her own discoveries about ancient soft-shelled eggs from dinosaurs. In the past, scientists assumed that dinosaurs had hard-shelled eggs like their living relatives - crocodilians and birds. Now, in the same issue of the journal "Nature," Wiemann and her colleagues describe fossils from two very different dinosaurs.
WIEMANN: We are definitely here dealing with the very first evidence for completely soft-shelled, non-biomineralized egg shells.
GREENFIELDBOYCE: Their chemical analysis shows that the young dinosaur offspring were surrounded by soft shells, much like the shells of turtle eggs. Wiemann says it looks like the earliest dinosaurs started out with soft-shelled eggs. Hard-shelled eggs evolved later.
WIEMANN: The dinosaur calcified egg is something that is not ancestral, that is not sort of a primitive feature of all dinosaurs.
GREENFIELDBOYCE: And now that researchers have shown how to find soft-shelled eggs in the fossil record, scientists will likely start finding more.
Nell Greenfieldboyce, NPR News.
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