Tiniest North American Dinosaur Lived Among Giants

Sunday, July 10, 2011

Though only as big as a squirrel, Fruitadens haagarorum -- a recently identified dinosaur from Colorado -- coexisted with enormous other species.

With the largest Fruitadens specimens weighing less than two pounds and measuring around 28 inches long, the North American dinosaur comes close to being the world's smallest, but not quite, according to a new study.

Watch video about the tiny dinosau

This diminutive dinosaur is, however, now North America's smallest known dinosaur. The 150-million-year-old creature is also the world's smallest known ornithischian dinosaur, a group that included horned, duck-billed and armored dinosaurs, along with many other diverse species.

"The smallest known dinosaurs -- just slightly smaller than Fruitadens -- are from China and they represent some of the closest relatives of birds," co-author Luis Chiappe told Discovery News.
"(The new dinosaur) may look bird-like because of its size, but in fact it isn't very closely related to birds or Archaeopteryx (the world's first known bird)," added Chiappe, who is director of the Natural History Museum's Dinosaur Institute in Los Angeles.

He and an international team of experts describe the new species in the latest Proceedings of the Royal Society B. The dinosaur's name was not inspired by edible fruit, but instead by the Fruita Paleontological Area, northwest of Grand Junction, Colo., where its remains were discovered.

Fruits were probably on its menu, however, along with eggs and almost anything else it could get in its mouth.

"The shape of Fruitadens' teeth suggests it was probably eating both plants and small animals -- i.e. insects," co-author Laura Porro told Discovery News.

She explained that in addition to being an ornithischian dinosaur, it was also a member of a family of dinosaurs called heterodontosaurids, meaning "different-toothed lizards." The teeth of these dinosaurs, like those of fellow omnivore humans, erupted in different shapes, with some resembling canines, others looking like molars and so on.

Most modern reptiles, such as alligators and iguanas, have more uniform teeth.

Relatives of Fruitadens, which have been found in England, South Africa and other countries, lived when "all continental land masses were connected into a single, giant continent called Pangea," Chiappe said. Some of these dinosaurs probably then traveled to North America, explaining how the bones of the tiny dinosaur wound up in Colorado.

"Colorado is the place where the rocks containing the fossils of Fruitadens are exposed, but presumably the species lived elsewhere in North America," he added, mentioning that it would have coexisted with other, much larger dinosaurs, such as Diplodocus and Brachiosaurus.

The presence of such gigantic herbivores may even help to explain why heterodontosaurids shrunk over the years and became omnivores. Not able to compete with the giant sauropods, "heterodontosaurs evolved to become small, ecological generalists. Think modern raccoons," Porro said.

"Dinosaurs were once thought of as large, lumbering plant or meat eaters," she added. "We now know there were lots of small dinosaurs about, that some dinosaurs were specialists that ate primarily fish or insects, that different species of plant-eating dinosaurs may have specialized in different types of plants, and that some dinosaurs may have climbed trees or even dug burrows."

She concluded: "We can now envision the world of the dinosaurs as a much richer, fuller place."

Visitors to the Natural History Museum in Los Angeles can soon view a display featuring the tiny Fruitadens next to the 70-foot-long dinosaur Mamenchisaurus, which also lived during the Late Jurassic.

For more information related to dinosaurs, visit rareresource.com.


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