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Oldest Embryo
Photograph courtesy Diane Scott, University of Toronto
The sharpest look yet at the oldest known dinosaur embryos (pictured, one of the eggs and its inhabitant) has revealed some "big surprises," a scientist says.
For one thing, the 190-million-year-old babies of Massospondylus—a two-legged dinosaur that preceded the well-known sauropods, such as Diplodocus—do not resemble their parents, according to study co-author Hans-Dieter Sues, a paleontologist at the National Museum of Natural History in Washington, D.C. (See more dinosaur-embryo pictures.)
The 8-inch-long (20-centimeter-long) youngster, for example, had long front legs for walking on all fours, and its overall body proportion—such as a short snout—made it "look like a dwarf version of a sauropod dinosaur," the largest animals to walk Earth. (See a sauropod picture.) The babies would have lost these traits as they matured.
The discovery suggests Massospondylus had characteristics that "foreshadowed" the later look of the sauropods, he said. (See "New Strong-Handed Dinosaur May Shatter Assumptions.")
—Christine Dell'Amore
The oldest-dinosaur-embryo research appears in the November issue of the Journal of Vertebrate Paleontology.
Published November 16, 2010
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Ill-Fated Embryo
Image courtesy Heidi Richter
The Massospondylus babies were ready to hatch (pictured, in an artist's reconstruction) when an early Jurassic flood likely entombed them in sediment, Sues noted.
High-powered microscopes allowed scientists to finally prepare and examine the "beautifully preserved" embryos, which were found near South Africa's border with Lesotho in 1976 and have since been stored in collections, he added.
(See pictures: "In the Womb: 'Extreme' Animal Embryos Revealed.")
Published November 16, 2010
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Baby Without a Bite
Photograph courtesy Diane Scott, University of Toronto
An artist's skeletal reconstruction of the Massospondylus embryo shows which bones were preserved in the fossils.
Though the babies' bones were fully formed—even down to their "little ear bones"—Sues and colleagues were shocked to find no teeth whatsoever in any of the embryos, he said.
Without teeth, the hatchlings "couldn't have run off and foraged by themselves" like most young dinosaurs, possibly suggesting that their parents raised them—unusual for dinosaurs, Sues noted.
(Related: "Dinosaur Dads Played 'Mr. Mom'?)
Published November 16, 2010
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