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Imprints of eggs and their broken shells, part of a 77-million-year-old dinosaur Reuters - Imprints of eggs and their broken shells, part of a 77-million-year-old dinosaur nest, are displayed ...
Slideshow: Fossilized Dinosaur Nest A rare fossilized dinosaur nest helps answer the conundrum of which came first, the chicken or the egg, two paleontologists say.
shared with birds, and our analysis can tell us how far back in time these features, such as brooding, nest building, and eggs with a pointed end, evolved - partial answers to the old question of which came first, the chicken or the egg," said researcher Francois Therrien, curator of dinosaur paleoecology at the Royal Tyrrell Museum in Alberta, Canada. Well, it's still unclear whether chicken eggs or chickens came first (the intended question in the original riddle), said Darla Zelenitsky, a paleontologist of the University of Calgary in Alberta who was the first scientist to closely analyze the dinosaur nest. But interpreted literally, the answer to the riddle is clear. Dinosaurs were forming bird-like nests and laying bird-like eggs long before birds (including chickens) evolved from dinosaurs. "Chickens evolved well after the meat-eating dinosaurs that laid these eggs." So the original riddle might now be rephrased: Which came first, the dinosaur or the egg? Meanwhile, the new nest provides some of the strongest evidence in North America in favor of the bird-like egg over the chicken. Rare dino nests The fossil nest was collected in the 1990s and kept at Canada Fossils Limited in Calgary, Alberta. That's where Zelenitsky first spotted the remains, which were labeled at first as belonging to a duck-billed dinosaur, an herbivore.
or a small raptor, both small meat-eating dinosaurs closely related to birds." She added, "Either way, it is the first nest known for these small dinosaurs." The only other egg clutch identified to date from a maniraptoran in North America belonged to Troodon formosus. Egg-laying behaviors The analysis of the nest, detailed in the latest issue of the journal Palaeontology, provides paleontologists with information about egg-laying in this particular dinosaur and others, along with the evolution of various egg-laying behaviors, Therrien said. "Our research tells us a lot about the dinosaur that laid the eggs and how it built its nest," he said. For instance, the position and spacing of the eggs suggest the original clutch contained at least 12 eggs arranged in a ring around the mound's flat top, where the theropod would have sat and brooded its clutch. The eggs were about 5 inches (12 cm) long and, like bird eggs, they were pointed at one end. The analysis also suggests the dinosaur laid its eggs two at a time on the sloping sides of the mound. That's unlike, say, crocodiles, which lay all their eggs at once, and more like birds, which lay one egg at a time. "There are dinosaur eggs from North America with baby bones preserved inside of them. It's entirely possible, but again these types of nests (from small meat-eating dinosaurs) are fairly rare." The research was funded by Richard and Donna Strong, the Alberta Ingenuity Fellowship Fund and the Killam Fellowship Fund.
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