miércoles, 22 de septiembre de 2010
Frilly-Horned Dino Found on 'Lost Continent'
* Two new species of dinosaurs are found in southern Utah where a long island once existed.
* One of the dinosaurs had a frill of horns along the top edge of its head and above its eyes.
* It's unusual that such a variety of large dinosaurs existed within such a small space at one time.
A newly found dinosaur featured strangely folded frill of horns on the top edge of its head and the horns that stick out sideways from above the eyes.
Two spectacular new species of horned, triceratops-like dinosaurs have been found in southern Utah, report paleontologists. The ornately frilled rhino-sized dinos are more than just eye candy, however. They are deepening a mystery about a long lost island that supported a seemingly impossible number and variety of dinos at the same time.
The giant plant-eating Kosmoceratops richardsoni and Utahceratops gettyi were found in the Grand Staircase-Escalante National Monument in rocks that were once part of a long island called Laramidia, which was separated from the rest of North America by a wide, shallow, north-south running seaway.
"It's a freaky dinosaur," said Matthew Lamanna, assistant curator at the Carnegie Museum of Natural History, commenting on Kosmoceratops. "If it were made into a kid's toy, it'd be a very popular one."
Among the things that make Kosmoceratops stand out are the strangely folded frill of horns on the top edge of its head and the horns that stick out sideways from above the eyes -- more like a longhorn steer than a dinosaur. The scientists are quite sure that none of these and other unusual features are artifacts of burial or damage after death for one simple reason:
"We actually have more than one skull," said paleontologist Scott Sampson, research curator at the Utah Museum of Natural History and lead author of a paper describing the new dinosaurs in the journal PloS ONE. Sampson is better known to children as "Dr. Scott," the host of the PBS Kids program, "Dinosaur Train."
Over the last few decades discoveries of Laramidian dinosaurs from Alberta to New Mexico have been revealing an unusually large number of both individuals and species living within a short span of time and varying from north to south.
For many years it was primarily the remnants of the northern end of Laramidia, found in Alberta, Canada, which were yielding great numbers of new dinosaur species from the late Cretaceous. Now the discoveries in Utah are beginning to catch up by representing the southern end of Laramidia.
Researchers have been surprised to find that instead of one or two species of dinosaur reaching across a large land mass -- as is the case with large mammals today -- there appear to have been many kinds of horned dinosaurs sharing the island.
Just how such large animals managed this is unknown, said Sampson. One possibility is that they had slower metabolisms than comparably-sized mammals, and so needed less energy and less food and space, Sampson explained.
It might also be that dinosaurs were just more prolific than comparable large mammals of today, says paleontologist Thomas Holtz of the University of Maryland. Fossilized nests show that this sort of dinosaur could lay a dozen eggs every year. A comparable mammal might have a single offspring every year that may take a dozen years to mature.
"Dinosaurs seemed to be more like weeds than trees," said Holtz. It could also be that the land was more productive in the late Cretaceous and could support more animals, he said.
As for what the ornate horns of the new dinos were used for, that's unknown, but the best best is they were all about looks.
"It was initially thought that they must be used as weapons," said Sampson. "It's much more likely it was used for show" to attract mates and/or repel competitors.