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  • Fossils show fast-growing dinosaurs

    Some of the oldest embryos ever are found in China
  • Scientists have discovered some of the oldest dinosaur embryos ever found, a rare collection of delicate fossils that offers an unprecedented look into the remarkably speedy early development of these enormous animals.
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  • Scientists have discovered some of the oldest dinosaur embryos ever found, a rare collection of delicate fossils that offers an unprecedented look into the remarkably speedy early development of these enormous animals.
    The bed of Lufengosaurus bones and smashed eggshell, described in Thursday's edition of the journal Nature, also may provide some insight into the growth of birds and other dinosaur relatives.
    "There's nothing like this that has been discovered before," said Luis Chiappe, a dinosaur paleontologist at the Natural History Museum of Los Angeles County, who was not involved in the study.
    The hundreds of bones the scientists extracted from a nesting site in southern China provide snapshots of embryos in different stages of development. They're thought to hail from the early Jurassic period, about 190 to 197 million years ago.
    Researchers from Taiwan first discovered the unhatched dinosaurs' mass grave after noticing a few tiny bones dribbling out of a hillock near farmland known for producing Lufengosaurus bones. But Lufengosaurus was a huge animal, growing as long as 30 feet. Such small bones — some the width of pencil lead — seemed out of place, said lead author Robert Reisz, a paleontologist at the University of Toronto Mississauga.
    The paleontologists followed the tiny bone trail, working on their bellies with hand tools. They carefully dug out a square-meter patch that turned up more than 200 bones from 20 individuals, in a spot that could have held more than three dozen eggs, Reisz said.
    Lufengosaurus, early cousins of the long-neck dinosaurs such as Brachiosaurus, appeared to like laying their eggs close to a water's edge, where they would partly bury them in damp soil, Reisz said.
    But living on the edge came with risks, and these eggs paid the price. The nest must have experienced a slow flood, drowning the embryos within.
    The water subsided and the eggs broke up — but the sluggish flow left the remains mostly in place, creating a 4- to 8-inch-thick muddled bed of tiny bones.
    Dinosaur embryo beds are exceptionally uncommon — the tiny, airy bones break up easily when an animal dies. Until now, the oldest embryos were the roughly 190-million-year-old remains of unhatched Massospondylus found in South Africa. Those, however, came encapsulated in their eggs, making them difficult to study.
    Lufengosaurus did paleontologists a favor. Since they tended to lay their eggs in the same spot as others, they created a sort of communal nest with a sample of embryos at different stages of development.
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