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WASHINGTON (AP) -- It was an ugly animal, with a mouth full of wicked teeth and a blunt head topped by horns, but it was the top meat-eater in almost half the world 70 million years ago and is now one of the best-preserved dinosaur skulls known to science.

"This thing was big, bizarre and ugly," said Scott D. Sampson, a dinosaur expert at the New York College of Osteopathic Medicine, which is part of the New York Institute of Technology in Old Westbury, New York. "It has a face that only a mother would love."

Sampson said the new dinosaur specimen, found in Madagascar last year, provides important clues about how the continents broke up and drifted during the 150-million-year reign of the dinosaurs.

A study of the new specimen is to be published Friday in the journal Science.

Dinosaur resembles one found in Argentina

Sampson, first author of the study, said the animal, called Majungatholus atopus, closely resembles a meat-eating dinosaur called Carnotaurus found in Argentina that most experts had considered a strange, unconnected, South American offshoot of the dinosaur clan.

"Now we find an animal in Madagascar that is a dead-ringer for it," Sampson said. "This means that this group spread out over most of the southern globe."

Sampson said the Madagascar discovery suggests that South America, India and Madagascar were all connected by a land bridge, probably Antarctica, when the animal species developed.

No such specimens have been found in Africa. This supports, but does not prove, that Africa was an "island continent" 70 million years ago, he said.

"This kind of dinosaur was known before only by one skull found in Argentina," said Paul Sereno, a dinosaur expert at the University of Chicago. "This is really a remarkable find."

Sereno said the skull was "a breathtaking specimen."

"The condition of the skull is what paleontologists dream about," he said.

Dinosaurs help trace the breakup of continents

Dinosaurs are providing a new source of evidence for the continental drift theory, said Sampson.

"The dinosaurs arose when all of the continents were united, and by the time the animals had died out, all of the continents had split up into about the way we recognize today," he said. "We can use dinosaur evolution as a means of testing this break up."

Sampson said the Madagascar meat-eater is a distant cousin of the Tyrannosaurus rex, the fierce hunter lizard that ruled North America in the dinosaur era. This means, he said, that the two species shared a common ancestry from the time that all the continents were joined in a single land mass called Pangaea.

Pangaea broke into two main chunks about 200 million years ago, scientists say. One piece, call Gondwana, included what was to become Africa, Antarctica, South America, Australia, India and Madagascar. It drifted south. The northern continents remained together as a land mass called Laurasia.

Dinosaurs' evolutionary paths differ

After Pangaea broke up, the dinosaurs in the north and south took different evolutionary paths.

Eventually, Gondwana also broke up, forming the present southern continents. India moved north to slam into Asia. It has long been thought that South America and Africa broke away as one unit and then later separated.

"If that is the case, we would expect the animals in South America and Africa to be more closely related," Sampson said. "But this animal found in Madagascar is more closely related to animals found in South America and India."

This suggests, he said, that Africa could have broken away from Gondwana before the other continents, causing dinosaurs in Africa to take an independent evolutionary path.

Sampson said this theory has not been proven, but, so far, no dinosaurs like the ugly meat-eater of Madagascar has been found in Africa.

Copyright 1998 The Associated Press.