Whereas the teeth at the back of the jaw are typical of theropods-being flattened and serrated-those at the front are longer and almost conical, with hooked tips and only tiny serrations. These features are otherwise unknown among theropod dinosaurs, which tend to have teeth of the same type front and back.
"When we dug up the first lower jaw bone, we weren't even sure it belonged to a dinosaur!" says Sampson. It was only after we compared it with the lower jaws of other carnivorous dinosaurs that we became convinced as to the nature of the owner. Certain features at the back of the jaw are unmistakably theropod."
Masiakasaurus shared its island home with at least one other carnivorous dinosaur, Majungatholus atopus. At 7-9 meters in length, Majungatholus was the top predator of the time, likely feeding on the massive long-necked sauropod dinosaurs also found there.
The diet of the smaller cousin, Masiakasaurus, with its unique teeth and jaws, is much less certain. There are a few species of living mammals-including various shrews, as well as a group of South American marsupials known as caenolestids-that may provide an analogue.
These mammals possess a similar dental set up, with elongate, conical, forward-projecting teeth up front. In virtually all cases, the front teeth are used for grasping and piercing rather than tearing and slicing, and the prey generally consists of insects.
The jaws of Masiakasaurus suggest a similar feeding strategy, with the front teeth used to capture and manipulate animal prey, and the blade-like rear teeth then slicing the victim into bite-sized chunks. As to the nature of the preferred prey of this little dinosaurian carnivore, potential candidates include insects, fish, lizards, snakes, and small mammals.
Masiakasaurus and Majungatholus, the two known Malagasy
theropods, are members of an enigmatic group know
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Contact: Cheryl Dybas
Cdybas@nsf.gov
703-292-8070
National Science Foundation
22-Jan-2001