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From the BBC:
Dinosaurs ‘grew fast, bred young’
By Helen Briggs
Science reporter, BBC News
Dinosaurs bred as early as age eight, long before they reached adult size, fossil evidence suggests.
Although they were descended from reptiles, and evolved into birds, dinosaurs grew fast and bred young, much like the mammals of today.
Researchers at the University of California found hallmark “egg-making” tissue in two juvenile females.
They say early sexual maturity was needed for survival, so females could lay eggs before becoming prey.
Sarah Werning and Andrew Lee of the University of California (UC), Berkeley, deduced from growth rings inside the bone that the two females were aged eight and 10, very young for dinosaurs, which lived to about 30.
Medullary bone has previously been found in a female Tyrannosaurus rex, and the scientists confirmed this finding, putting her age at 18.
“We were lucky to find these female fossils,” said Sarah Werning. “Medullary bone is only around for three to four weeks in females who are reproductively mature, so you’d have to cut up a lot of dinosaur bones to have a good chance of finding this.”
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