There were already two Jurassic dinosaur skeletons mounted in India. Neither, however, represents a single skeleton, but is instead based on composites of isolated bones.
"We know that there were carnivorous and herbivorous dinosaurs in India through individual bones, but we really don't know just how they looked because no two bones can be reliably said to belong to one individual," said Wilson, who is of the University of Michigan. "Rajasaurus is important because it represents a partial skeleton and preserves many details that clue us into its evolutionary relationships."
The reconstructed skull is missing some parts, but it has the most important pieces: the jaws and the brain case. Between 25 and 30 feet (7.6 and 9 meters) long, the Rajasaurus was heavy and strong, and walked on two legs.
"There are several anatomical details that make Rajasaurus a new species," said Wilson. "Perhaps the most striking is the horn it bears on its head. The horn was probably rather subtle. It may have been low and rounded."
A Carnivorous Family
The carnivorous Rajasaurus, which lived in the Cretaceous Period at the end of the dinosaur age, preyed on long-necked titanosaur sauropods, herbivorous dinosaurs that also roamed the Narmada region. Bones from both dinosaurs were found together.
Indian paleontologists recently found coprolites (fossilized dung) that provide additional clues to the diet of those titanosaurs.
"Large theropod eggs have also been described by our group from the area where the skeleton of Rajasaurus has been recovered, but it's difficult to relate the theropod eggs specifically to Rajasaurus," said Sahni.
The scientists believe the Rajasaurus is related to a family of large carnivorous dinosaurs, most of which had horns, that roamed the southern hemisphere land masses of present Madagascar, Africa, and South America.
"People don't realize dinosaurs are the only large-bodied animal that lived, evolved, and died at a time when all continents were united," said Sereno.
Continental Drift
The Rajasaurus was likely like its contemporary, Tyrannosaurus rex—one of the last species to live before a catastrophe occurred some 65 million years ago.
What exactly caused the death of the dinosaurs is a matter of great debate. But the burial site of the bones found in India could provide a clue.
"The sediments in which these dinosaurs were found are closely associated with one of the biggest volcanic activities recorded in the last 500 million years on planet Earth," said Sahni.
As much as a third of India's land mass is covered with lava. That makes it particularly difficult to find dinosaur bones. The task is made even more difficult because India is so heavily populated.
"The best place for a paleontologist to work is an empty desert," said Sereno.
Dinosaur discoveries could also help researchers improve their relatively scant knowledge of how India separated from Africa, Madagascar, Australia, and Antarctica and later impacted Asia to form the Himalaya.
"The details of the timing and route of India's northward migration are not well resolved," said Wilson. "Dinosaurs are good organisms to study the effects of continental drift because they cover continent-scale distances. That is, they seem to record connections between continents fairly well."
The new species will be described in the August issue of the Contributions of the Museum of Paleontology of the University of Michigan. Casts of the dinosaur's skull will be donated by the team to Panjab University and the Geological Survey of India.
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Additional Dinosaur Resources from National Geographic:
Paul Sereno: National Geographic Explorer-in-Residence and Dinosaur Hunter
Dinorama
Wanted: Albertosaurus
Dinosaur Eggs
Pterosaurs
Destinations: Dinosaur National Monument
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