may the force be with you

The finding, reported today in the journal Science, gives paleontologists new insights into the physical development of dinosaurs. Examination of the fetal skeleton also suggests the hatchling would have required parental care to survive. This would be the earliest evidence of nurturant behavior, more than 100 million years earlier than previous examples.

"It's a very exciting prospect that means this is the oldest example of parental care," says lead researcher Robert Reisz, paleontologist at the University of Toronto at Mississauga.

Since the 4.7-inch-long skeleton fills the slightly round 2.4-inch-long egg, it appears the dinosaur was near hatching.

The egg containing the embryo was discovered in 1978 in South Africa, but it was too tiny and delicate to be dissected. Using a special microscope Reisz created and miniature excavation tools, researchers were able to expose the skeleton from the surrounding rock and eggshell. Reisz says it is "superbly preserved."

The embryo, a Massospondylus, belongs to a family of dinosaurs called prosauropods. Distantly related duckbill dinosaurs in the late Cretaceous period, 99 million to 65 million years ago, also seemed to have cared for their young, but according to Thomas Holtz Jr., vertebrate paleontologist at the University of Maryland, "duckbills are mental giants" compared with the prosauropods.

The most significant aspect, Holtz says, is that "even very primitive dinosaurs were showing fairly sophisticated parental behavior."

James Clark, professor of biology at George Washington University, is not convinced. He says the actual ability of the baby dinosaur "is something that is really hard to know." What he finds more impressive in the study are "the changes that they documented going from the embryos up through the adults. It looks like they were changing their body posture."

Adult prosauropods were about 16.4 feet long, primarily walked on their hind limbs and might have looked a bit like Fred Flintstone's pet Dino, Holtz says.

The tiny embryo has a large head and larger forelimbs, suggesting it would have initially walked on all four legs. It appears the forelimbs grew more slowly than the hind limbs, leading the prosauropod to change its gait.

The skeleton also may provide insight into an evolutionary mystery. Prosauropods are precursors to sauropods, a family that includes large dinosaurs such as the Apatosaurus, also known as brontosaurus. Some features of the embryo resemble adult sauropods, so sauropods may have evolved through paedomorphosis, a process where young traits are retained in adulthood.

source:http://www.sci-tech-today.com/story.xhtml?story_id=37548