Late Cretaceous Dinosaurs from Madagascar
Dinosaurs were first discovered in Madagascar by British and French paleontologists late in the 19th century. The fossils were rather scrappy, but they included Jurassic and Cretaceous sauropod (brachiosaurid and titanosaurid) and theropod bones. In 1926, a fossil tooth from Madagascar was described by the French as belonging to a new species of Stegosaurus; the French named the theropod Majungasaurus. And in 1979, a thickened skull bone was described as a pachycephalosaur called Majungatholus. Every so often a few more scrappy dinosaur bones were found there, but this was essentially where dinosaur paleontology of Madagascar stood as late as the mid-1990s.
In 1996 and following years, American expeditions to Madagascar found fairly plentiful bones of Late Cretaceous dinosaurs, including two kinds of titanosaurids (still undescribed); a large theropod; a new kind of small to medium-size theropod with front teeth that protrude forward almost horizontally; a small, birdlike theropod with a long tail that had large, winglike forelimbs and was probably a good flier; and a "true" bird that was named Vorona. The new material settled some doubts about Madagascar dinosaurs. First, the aforementioned stegosaur tooth was found to belong to a peculiar kind of crocodile and was not stegosaurian after all. Then, the so-called pachycephalosaur turned out to be a theropod with a bumpy, thickened skull roof and a short snout. A good skull showed that Majungatholus was a close relative of the peculiar South American horned theropod Carnotaurus; instead of a pair of horns, it had a single thick knob on top of its head. The earlier name Majungasaurus had to be discarded because the material on which it was based was too scrappy to identify; it may or may not be the same dinosaur as Majungatholus.
The small theropod with protruding front teeth was named Masiakasaurus in early 2001. The available material suggests that it may be related to the small theropod Noasaurus from South America, but further work needs to be done before this identification is secure. Some speculate that it was a fish-eater.
The small, birdlike theropod, called Rahonavis, is perhaps the most interesting fossil found by those expeditions to Madagascar. Although the describers classified it as a bird about as advanced as the Jurassic bird Archaeopteryx, its feet are almost exactly the same as the feet of Deinonychus and other dromacosaurids, right down to the enlarged "killer" claws. The long tail and hips also closely resemble those of dromaeosaurids, but the forelimbs have the long, slender bones of bird wings and little bumps where feathers might have been attached. Thus, Rahonavis seems to be a genuine link between small theropod dinosaurs and "true" birds. Only further study, and some more specimens, will resolve the relationship of theropods, birds, and Rahonavis.