BIRD-LIKE EGG FOUND INSIDE DINOSAUR

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Date: Saturday April 30, 2005 10:08:00 am
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    Bird-like eggs found inside dinosaur
    Rare fossil discovery offers clues to evolution

    WASHINGTON – The
    rare discovery of eggs inside a dinosaur has given scientists new clues about
    the reproductive biology of the creatures and more support for the theory that
    birds came from dinosaurs.

    The pair of shelled
    eggs is the first of its kind found inside a dinosaur, said researchers who
    reported the discovery in Friday’s issue of the journal Science.

    Scientists found
    the dinosaur produced eggs in some ways like a crocodile and in other ways like
    a bird. Crocodiles and similar primitive reptiles have two ovaries enabling them
    to lay a clutch of eggs. Birds have a single ovary and can only lay one egg at a
    time.

    The dinosaur’s
    egg-producing capability lay somewhere in between, suggesting a link with the
    modern bird, researchers said. It could produce more than one egg, but only one
    from each ovary at a time.

    The theory that
    birds came from dinosaurs has been supported by many researchers, said Tamaki
    Sato of the Canadian Museum of Nature in Ottawa. But this latest research helps
    advance it, she added, calling it “strong evidence.”

    There have been
    previous findings of round objects around dinosaur skeletons and scientists have
    suspected they might be eggs but because they did not have shells, there wasn’t
    certainty, Sato said.

    “You have egg
    shells with this one,” she said of the specimen at the National Museum of
    Natural Science in Taiwan that was excavated from China. “This is the first time
    for sure.”

    The scientists
    studied a dinosaur from a group of dinosaurs called oviraptorosaurians. This
    type of dinosaur — probably 10 feet to 13 feet long — is a subgroup of the
    theropods, thought to have been the ancestors to modern birds.

    The remains of the
    shelled eggs looked like pineapple-sized potatoes. The similar size of the eggs
    suggests the creature’s two oviducts each produced a single, shelled egg at the
    same time, the report said.

    Matt Carrano,
    curator of dinosaurs at the National Museum of Natural History in Washington,
    said the findings provide greater insights into the biology of the dinosaur and
    the evolution of birds.

    “It’s a window into
    a particular stage of evolution,” he said. “This particular dinosaur has
    characteristics that are birdlike but retains reptillian-like
    features.”

    “You have oviducts
    but they’re only doing one egg at time. Its biology is half way there between a
    bird and reptile.”

    Carrano also said
    it tells something about birds.

    “The evolution of
    one egg at a time happened very early, before birds could fly, and then the
    evolution of only one oviduct happened later,” he said.

    “That might be
    related to the origin of flight,” he said, explaining that maybe birds wanted to
    lighten their body and so developed one oviduct.

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