Dinosaur in a Coal Mine
from the book, "Our Fascinating Earth"
Dinosaur in a Coal Mine
During the Cretaceous Period, about one hundred million years ago when dinosaurs still dominated the earth, erosion had cut a ravine 200 feet deep into what is now Belgian soil. A wide coal seam, deposited about 200 million years before, was visible about halfway down the cliff face. Erosional processes had cut right through the ancient coal deposit. It was into this deep ravine that no fewer than thirty—one adult dinosaurs of the genus Iguanodon had fallen in quick succession, lodging at various levels on its lower slopes. With the passage of time the ravine underwent numerous floods and was gradually filled with Cretaceous muds that buried the dinosaur skeletons and in time completely filled the ravine.
In 1878, in the Belgian coal mine at Bernissart, a most extraordinary discovery was made. Some miners who were developing a new gallery encountered numerous fossil bones at a depth of more than 1,000 feet. They had picked their way almost completely through one skeleton before becoming aware of its presence. A noted paleontologist was called in to survey the situation. He recognized the bones as belonging to Iguanodon and observed that they were present in great numbers. Excavation then proceeded in earnest. A scientist—engineer, M. De Pauw, spent the next three years directing the work of digging out the skeletons.
At first they tried to excavate under the fossil graveyard by digging another tunnel more than a hundred feet below the original find, but again bones were encountered. This dinosaur cemetery was evidently of gigantic proportions, with its vertical extension through more than a hundred feet of rock. It became obvious that the bones were not contained within the stratified beds of the mine but instead were embedded in unstratified clays of a later geologic period. These filled a cut through the layered coals and shale. In short, the Iguanodon bones were distributed in what had once been a deep ravine, cut into the older Carboniferous (coal—bearing) rocks. The bones were embedded in the unstratified clays that had in time filled the ravine.
The meticulous mapping of the mine was coordinated with excavations of the fossils and revealed in detail the ancient landscape just described. The outline of the banks of the Cretaceous ravine was delineated by the inwash of sediments that filled it. These sediments were quite distinct from the regular stratified layers of coal and shale that were being mined so far beneath the surface of the earth.
The reconstruction and mounting of the recovered skeletons was done under the direction of paleontologist Louis Dollo, who devoted the rest of his career to the preparation and description of Iguanodon. He mounted the first skeleton in 1883, and by the turn of the century four more had been erected, all in lifelike positions. At present the Royal Museum in Brussels houses thirty—one specimens, eleven standing skeletons with twenty additional complete and partial skeletons recumbent at the base of the exhibit.
It is not difficult to re—create the scene as it happened on that Cretaceous day about one hundred million years ago. As was their daily routine, a herd of Iguanodons was feeding on a large patch of vegetation overlooking a deep ravine. Although absorbed in their meal, they kept a wary eye on the nearby jungle, knowing that it could easily shelter a hunter looking for a meal. Their worst fears were realized when suddenly two monstrous carnivores charged out of their forested cover and sank their teeth and claws into a large Iguanodon that had wandered too close to retreat. The helpless animal howled in pain and terror, causing an immediate reaction from its fellow Iguanodons. Their behavior was essentially no different from that of present—day prey animals reacting to the charge of a pride of lions.
Almost instantly the entire herd of Iguanodons turned and stampeded away from the scene of the attack. All ran in the direction of the deep ravine, and in their undefinable terror the entire herd stampeded off the cliff that lay to the south. Briefly the air was filled with cascading dinosaurs, turning and twisting, striking the slopes of the ravine about one hundred feet form the top. Here their broken bodies continued to downward trip, rolling and tumbling until they finally came to rest either somewhere along the slope or at the bottom of the 300—foot ravine.
Not all were killed by the fall, and the luckier few hit the gentler incline of the ravines' slope. These survivors were doubtless badly bruised as they fell to the bottom. They were, at least, in no danger from the carnivores as they struggled painfully to their feet and limped away, living to run another day.
Most of the herd fell where the incline of the cliff was quite steep, and they died on impact. A few battered specimens may have tried to get to their feet and move away, but broken bones cannot support a four— to five—ton body. When the dust cleared, the bottom of the ravine near the north slope was virtually covered with the broken bodies of a herd of Iguanodons, some still waving their heads feebly as they breathed their last.
On the flatlands above the ravine the two carnivores, alone with their victim, began to feed.