Bird-Like Dinosaur Sat On Eggs

Nov. 13, 2008 -- An animal that looked like a big bird, had feathers like a bird, laid eggs like a bird and behaved like a bird was, in fact, a dinosaur, according to paleontologists who just linked such a dinosaur with a nest full of neatly arranged eggs.

The 77-million-year-old findings could represent one of the last dinosaur species before certain dinosaurs fully evolved into birds.

The carnivorous, feathered egg layer was likely either a caenagnathid, meaning a member of a group of emu-like dinosaurs, or a dromaeosaurid, which zipped around on two legs.

"We now know that egg-laying traits required gradual evolutionary changes," study leader Darla Zelenitsky told Discovery News.

Zelenitsky, a University of Calgary paleontologist, explained that the nest, found at Two Medicine Formation, Mont., during the 1990's, resembled previously excavated dinosaur nests belonging to an oviraptor and a troodontid. The Montana nest, however, is also very bird-like.

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She and colleague Francois Therrien of the Royal Tyrrell Museum of Paleontology first discovered the nest in a private collection housed at Canada Fossils Limited in Calgary. It was labeled as belonging to a hadrosaur, or an herbivorous duck-billed dinosaur.

Such plant specialist dinosaurs are probably not as closely related to birds, which tend to have varied diets that can include everything from seeds to insects to small animals.

The researchers analyzed the nest and its contents in greater detail. Based on its characteristics, they determined that a small meat-eating dinosaur had instead carefully constructed the nest.

The findings are published in the latest issue of the journal Palaeontology.