Carnivorous dinosaur eggs discovered


Carnivorous dinosaurs

From National Geographic:

November 14, 2008—If it looks like a duck-billed dinosaur nest, it’s probably from a duck-bill—unless it’s a newly identified clutch of fossilized eggs from a private collection in Calgary, Canada.

The eggs, originally found in Montana in the 1990s, actually belong to a carnivorous dinosaur—either a creature related to the fearsome velociraptor (seen above, top left) or a birdlike, upright-walking dinosaur called a caenganathid [spelled wrongly; should be caenagnathid] (top right), a new study says.

Nests for neither of the predators have never been found, making the discovery a major one, according to University of Calgary paleontologist Darla Zelenitsky, who led the study in the journal Paleontology.

When Zelenitsky and colleagues first examined the eggs, they noticed some irregularities that did not point to plant-eating duck-bills, which are not directly related to birds. (See a duck-bill illustration.)

For one, the ancient parents left their eggs open to the elements, probably so the creatures could brood their young as a bird would. The eggs were also pointed, like bird eggs.

(Related: “Dinosaurs Were Doting Parents, Fossil Find Suggests” [September 8, 2004].)

The nest is also the first to be found that preserves the mound (above, bottom) on which the eggs were laid, added Zelenitsky.

—Matt Kaplan

Images courtesy University of Calgary

4 thoughts on “Carnivorous dinosaur eggs discovered

  1. Rare dinosaur nest offers look into bird evolution
    Fri Nov 14, 2008 3:19am EST

    By Scott Haggett

    CALGARY, Alberta (Reuters) – Canadian researchers say they’ve narrowed down the likely owner of a dinosaur nest, abandoned on a river’s edge 77 million years ago, adding the discovery offers a unique look at dinosaur reproduction and the evolution of birds.

    Scientists from the University of Calgary and Alberta’s Royal Tyrrell Museum say the nest unearthed in northern Montana in the 1990s likely belonged to one of two types of small, carnivorous dinosaurs.

    The two suspects are a ceanagnathid, which looks somewhat like an ostrich, or a small raptor called a dromaeosaurid. Both are small by dinosaur standards and related to modern birds.

    The nest likely held up to a dozen eggs, of which only fossilized fragments remain.

    “We think, based on characteristics of the eggs, that we are probably dealing with a nest from a small raptor but we can’t (be) 100 percent sure and rule out the other one,” said Francois Therrien, curator of dinosaur palaeoecology at the Royal Tyrrell and co-investigator.

    Nests from meat-eating dinosaurs are extremely rare. Only one other example has been found in North America, a nest of 67-million-year-old Troodon eggs that was also unearthed in Montana.

    Therrien said the latest nest was discovered by commercial fossil hunters and originally thought to be from a relatively common duck-billed hadrosaur.

    Darla Zelenitsky, a University of Calgary paleontologist, realized that the nest, a raised mound 50 cm (20 inches) across and surrounded by eggs, was actually from a small meat-eater.

    Zelenitsky is the lead author of a paper on the nest, published on Thursday in the journal Paleontology.

    Therrien said the find gives scientists new information on the evolution of reproduction in small carnivorous dinosaurs, filling in key gap in their knowledge and offering insight into how birds’ methods of laying eggs and brooding evolved.

    “This nest reveals that modern birds are not unique in the way they reproduce,” Therrien said. “They actually inherited a lot of their ways of laying eggs from their dinosaur ancestors.”

    The nest was acquired by the Royal Tyrrell in 2006 and will be put on display in the museum in Drumheller, Alberta.

    (Editing by Rob Wilson)

    © Thomson Reuters 2008

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