ATHENS, Ohio -- Majungatholus atopus had a face so ugly, it was worthy only of a mother's love -- and that of the team of scientists who have recovered an unusually well-preserved specimen of the large predatory dinosaur in Madagascar. The find provides new information about a dinosaur family previously found only in South America and India and offers an alternative to long-held theories of how the Earth's continents split millions of years ago.
The discovery was reported in the May 15 issue of the journal Science by researchers from the New York Institute of Technology, Ohio University in Athens, the State University of New York (SUNY) at Stony Brook, the University of Pennsylvania and the Universite d'Antananarivo in Madagascar.
Scientists recovered pieces of the animal's tail and a near-complete skull, and although the skull bones were scattered over a 2-meter area, they were remarkably well-preserved, says Lawrence Witmer, an assistant professor of anatomy in Ohio University's College of Osteopathic Medicine and co-author of this new study.
"People usually think the best type of fossil is an intact specimen, but that's not true," Witmer says. "Intact fossils don't allow scientists to see an animal's internal structures. This fossil is special because, not only was it found as separated bones, it also was so well-preserved, we can actually fit the bones together like a puzzle."
Witmer is studying fiberglass casts of the fossils, working with the study's lead author Scott Sampson, an assistant professor of anatomy at the New York College of Osteopathic Medicine of New York Institute of Technology.
It appears the animal was buried during a flood soon after its death, protecting the remains from scavenging and decomposition, says David Krause, professor of anatomical sciences at SUNY Stony Brook and leader of the 1996 expedition team that made the discovery.
The fossil's good condition is just one of many reasons the scientists are excited about their find, Sampson says. Perhaps of even greater importance is the animal's strong resemblance to a horned theropod called Carnotaurus, known only from Argentina. Both Majungatholus and Carnotaurus belong to the dinosaur family Abelisauridae, which lived during the Late Cretaceous period. Previously, members of this family have been found only in India and South America.
The occurrence of such closely related dinosaurs on widely separated landmasses supports a new hypothesis for plate tectonics -- the theory that landmasses shift their relative positions as they move slowly across the face of the earth.
"Dinosaurs lived at a time when all of the continents were connected, so we can use them to test hypotheses about the timing of the break up of the Earth's continents," Sampson says. "Until now, people assumed continents split in a particular pattern, which included South America and Africa breaking away as one unit.
"If that is the case, we would expect the animals in South America and Africa to be more closely related. But this animal found in Madagascar -- an island off the southeast coast of Africa -- is more closely related to animals found half way around the world."
The researchers suspect that a land connection composed largely of Antarctica may have existed between South America and Madagascar during much of the Cretaceous period, allowing dinosaurs to travel the great distances between these areas.
"One might predict that Antarctica, and possibly Africa, would be a good place to look for more abelisaurids," Witmer says.
Majungatholus was originally named for an isolated skull fragment thought to belong to a pachycephalosaur, or "dome-headed" dinosaur. But this new skull clearly shows that Majungatholus wasn't the veggie-eater scientists had long believed, but was instead a carnivorous theropod and distant cousin to Tyrannosaurus rex.
"This finding is significant for understanding global distributions of dinosaurs because Majungatholus was previously the only pachycephalosaur reported from the southern hemisphere," Sampson says.
Preliminary studies of Majungatholus suggest it had a total body length of 7 to 9 meters and was the top predator of the time on Madagascar, likely feeding on the massive long-necked sauropod dinosaurs also found there.
Majungatholus had a very unusual bone structure and facial features that the researchers suspect were used to send visual signals to attract potential mates or threaten potential enemies. Its facial bones were rough and wrinkled and it had a bony bump above its eye sockets. The bump likely was covered with some sort of epidermal horn, perhaps similar to the horn on a rhinoceros.
"This skull is weird and wonderful -- and ugly," Sampson says. "The face of Majungatholus may well have appealed to members of the opposite sex, but not from any other species!"
The structure of its lower jaw suggests it had an intramandibular joint that allowed movement within the lower jaw. This type of joint would have made it easier for Majungatholus to chew its food, and is similar to joints found in some modern-day birds, lizards and snakes.
"This skull will provide us with a lot of information about muscles, blood vessels and other tissues that is difficult to get from other, poorly preserved fossils," Witmer says. "But we'll learn even more by comparing Majungatholus to similar modern-day animals, which is true for all studies of extinct species."
Scientists found the 65 to 70 million-year-old Majungatholus fossils in an area about 25 miles from Mahajanga, one of Madagascar's largest cities. They first discovered pieces of the animal's tail and found its skull several days later.
"We were initially disappointed when discovery of the tail did not immediately lead to discovery of the hip and then the rest of the skeleton," Krause says. "Instead we started finding bones of a poorly preserved sauropod."
But a few days later, as Sampson and other members of the expedition continued excavating the site where the tail was found, Sampson hit the paleontological jackpot.
"This was the most terrific find I have been associated with in more than 25 years of field work," says Krause, who now has led three expeditions to Madagascar as part of a project to map the entire fauna of the region. The expedition team will return to Madagascar in June to continue their work.
Other study authors include Catherine Forster and Patrick O'Connor, SUNY Stony Brook; Peter Dodson, University of Pennsylvania; and Florent Ravoavy, Universite d'Antananarivo, Madagascar. The work was supported by the National Science Foundation, The Dinosaur Society and the Field Museum of Natural History in Chicago.
This is one of several projects on which Witmer and Sampson are collaborators. The two are partners on a project dubbed the "DinoNose Grant," which also is supported by the National Science Foundation. Witmer is the principal investigator on that project, designed to study extinct and modern-day animals in an effort to reconstruct soft tissues not preserved in the fossil record.
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Contacts:
Lawrence Witmer, Ohio University, (740) 593-9489; witmer1@ohiou.edu
Scott Sampson, New York Institute of Technology, (516) 686-3807;
ssampson@iris.nyit.edu
David Krause, State University of New York, Stony Brook, (516) 444-3117;
dkrause@mail.som.sunysb.edu
Written by Kelli Whitlock, Ohio University, (740) 593-0383; kwhitlock1@ohiou.edu
Journal
Science