Madagascar's buried treasure

Natural History, March, 1997 by Scott D. Sampson, David W. Krause, Catherine A. Forster

Dinosaur fossils spill from the hills around the tiny village of Berivotra in northwestern Madagascar. The bones are exquisitely preserved, giving the impression that the beasts died within the past few month instead of 75 million years ago in the Late Cretaceous. Unfortunately the thick grass covering much of the terrain tends to thwart the efforts of fossil hunters like us. So at one promising hill, we dug a fire trench and stood back to watch Retsieva, a Berivotra resident, set fire to a small area of waist-high grass. As a dark plume of smoke arose, even the most positive thinkers among us never imagined that this nondescript hillside would become the most important paleontological site ever discovered in Madagascar and one of the most significant found anywhere in the world in recent years.

Known as the Great Red Island for its size and the color of its iron-rich soils, Madagascar sits like an immense ruby in the southern Indian Ocean. Once part of the southern supercontinent of Gondwana, Madagascar became an island almost 90 million years ago. This long isolation has contributed to the remarkable number of endemic species on the island: 85 percent of its living plants and animals are found nowhere else. Until recently, however, little was known of the island's extinct fauna, including dinosaurs.

While dinosaurs were (and still are, in the guise of birds) a global phenomenon, the best known are from the Northern Hemisphere. These include such renowned creatures as Tyrannosaurus and Triceratops from western North America and Velociraptor from the Gobi Desert of central Asia. Our scant knowledge of ancient life south of the equator has been due not to a lack of fossils but to a collecting bias. Until recently, few paleontological expeditions had explored southern regions. To remedy this situation, expeditions have been undertaken in the past few years in Argentina, Brazil, Morocco, Malawi, Niger, South Africa, India, Australia, and Antarctica. The abundant dinosaur and other vertebrate remains found in these new sites include many previously unknown animals. These fossils are providing clues to ancient continental connections, as well as to the relationships of creatures inhabiting lands that once made up Gondwana.

In the austral winters of 1993, 1995, and 1996, we traveled to Madagascar as members of joint expeditions sponsored by the State University of New York at Stony Brook and the University of Antananarivo, in the capital of the island country. Prior to 1993, several French, Malagasy, and Japanese expeditions had visited the Berivotra area, known formally as the Mahajanga Basin, and had established the presence of at least two kinds of dinosaurs and a variety of other vertebrates. These isolated and predominantly fragmentary specimens had received minimal attention. Yet, for us, they held great promise for future discoveries and indicated where we should begin the search.

Our 1993 visit to Madagascar was mainly a reconnaissance trip to evaluate the potential of the area not just for dinosaur remains but for all vertebrate fossils. The most common fossils in the Berivotra area are isolated teeth of a large, poorly known carnivorous dinosaur, dubbed Majungasaurus many years earlier by French paleontologists. In addition to finding more tantalizing bits of Majungasaurus, including a beautifully preserved bone from the upper jaw, we found four skeletons of a small, gracile crocodile, Araripesuchus, otherwise known only from South America and northern Africa, and a single, partial tooth of a mammal.

Although visually unspectacular, the mammal specimen is extremely important. It represents the first documented record of mammals from Madagascar prior to 26,000 years ago and the first occurrence of a Gondwanan mammal outside of South America and India from the 32 million years that make up the Late Cretaceous. But these finds were only the beginning. In addition to specimens of other theropods (swift, bipedal, meat-eating dinosaurs) and crocodiles, we unearthed remains of sauropods (large, quadrupedal, herbivorous dinosaurs), turtles, snakes, lizards, frogs, bony fishes, sharks, and rays.

In total, we discovered more than one hundred fossil-bearing localities. Each was given a number and its precise geographic location was recorded with the help of a satellite-assisted Global Positioning System (GPS). On one hillside, several vertebrae of a sauropod and the toe bones and tail vertebrae of a theropod offered the enticing possibility of at least two skeletons to be investigated on our next expedition.

In 1995, we returned to Madagascar. We soon discovered and began unearthing the nearly complete skeleton of a previously unknown large crocodile. This time, however, our sights were set on bringing home dinosaurs. So it happened that on a pristine July morning, Retsieva touched a torch to the dry grass on the promising hillside discovered in 1993. Once the smoke had cleared, we soon found several spots where whitish dinosaur bones protruded from the now blackened surface.