Insights From Island Of 'Terrible Lizards'
Digging in the sandstone hills of Madagascar, scientists have found one of the best preserved dinosaur skulls ever - yielding new clues about an island that once was a playground of the "terrible lizards."
The meat eater's remains not only are giving new information about a little-known animal, they also are providing fresh insights into how the planet as a whole was reshaping itself 100 million years ago. Moreover, its discovers say, the skull suggests that the predator had features that bear a faint resemblance to those found on birds, fueling an already heated debate about whether birds evolved from predatory dinosaurs.
Based on initial studies of the remains, the creature, named Majungatholus atopus, was about 30 feet long and at the top of the food chain. Its primary meal was likely to be long-necked Brontosaurus-like dinosaurs, whose remains have also been found there.
Much of the evidence that Madagascar, an island off the east coast of Africa, was once a preserve of huge prehistoric lizards, has come from fossilized bone fragments and teeth discovered during the past 100 years, according to Scott Sampson, the researcher who discovered the remains during a 1996 expedition. It was the teeth, many with edges serrated like steak knives, that tantalized him, he adds. "We really wanted to find their owner."
During the expedition, he noticed what looked like a tail bone on a hillside. "I chased the tail into the hillside, hoping to find the rest of the animal," he recalls. Instead, he found the limb bone from a brontosaurus-like animal. Only later did he come across the upper jaw and the rest of the skull. "It was a beautiful, nearly complete skull. It was almost like a kid's dinosaur toy. You could literally snap the segments together to get the complete skull," he says.
The skull's features have prompted the researchers to rewrite the book on Majungatholus's relatives. A Majungatholus skull fragment found years ago prompted paleontologists at the time to suggest that the creature was a thick-skulled plant-eater related to similar dinosaurs found only in the Northern Hemisphere. Instead, except for the pattern of horns on its skull, Majungatholis - a distant cousin of the infamous Tyrannosaurus rex - is "a dead ringer" for members of another group of dinosaurs found in South America and India, says Dr. Sampson, assistant professor of anatomy at the College of Osteopathic Medicine at the New York Institute of Technology.
The dinosaur family's geographic diversity is helping scientists pin down the history of the formation of today's continents.
"Majungatholus actually is a new member in a family of abelisaurids" whose only other members appeared as bone fragments in India and one skull in South America, says Lawrence Witmer, a member of the international research team and assistant professor of anatomy at Ohio University in Athens. With Majungatholus as an added relative, their relationships and ages "fit closely with the pattern of break-up of the continents."
Majungatholus, whose discovery is reported in today's issue of the journal Science, is reinforcing the idea that Antarctica, Africa, South America, and India remained connected much longer than what was previously believed, with Antarctica serving as a bridge between South America and what was to become India and Madagascar as recently as 80 million years ago. Previous work had suggested that the break came some 45 million years earlier.
Although many paleontologists say Majungatholus is not as close a relative to birds as dinosaurs such as velociraptor, the meat eater from Madagascar does have some primitive bird-like characteristics, Dr. Witmer says. The skull shows evidence suggesting that visual displays such as colorful markings were important either in mating or in determining the social pecking order, he says. "We find similar characteristics in birds today, from bright feathers to skull ornaments."