On August 3, 1960, a party of geol­ogists from several countries was exploring the top of a vertical sandstone cliff in the remote islands of Spits­bergen halfway between the northern tip of the Scan­dinavian Peninsula and the North Pole. (The sandstone here was formed in the Cretaceous Age, the last period of the Mesozoic Era that constitutes the Age of the Rep­tiles.) The scientists were participating in a field excur­sion led by Professor Anatol Heintz of the University of Oslo.

Two members of the group, Professor Albert F. de Lapparent of Paris and Robert Laffitte, climbed down the cliff to the shore. As they looked back up at the wall towering above them, they saw on its surface a number of huge footprints.

Within a few moments the rest of the group scrambled down the cliff to look at the tracks.

They counted 13 footprints, each distinctly three-toed, and each between 25 and 30 inches (76.2cm) long! Seven of the prints formed a 45-foot trackway obviously made by an animal walking on its hind legs. The other footprints were scattered in various directions. There was no doubt in the minds of the viewers that they were looking at the footprints of a large dinosaur.

The geologists thought at first that the impressions were those of a gigantic, meat-eating dinosaur similar to Tyrannosaurus Rex. But careful examination of the prints showed less prominent claws. It was therefore concluded that the tracks were probably made by large, blunt-toed, plant-eating dinosaurs.

Subsequent study of the prints by Professor de Lapparent convinced him that these were made by the Lower Cretaceous dino­saur Iguanodon, that lived about 100 million years ago.

The discovery of these dinosaurian footprints was both exciting and frustrating. In the words of de Lapparent, 'As this discovery was entirely unexpected, we were unable to make castings. . . . We did not even have a piece of chalk to show up the outlines of the prints. . . . After having measured the footmarks and made sketches, we were obliged to leave, as the Valkyrien was waiting to depart. . . ." the tracks were so important that plans were made to return to make casts of them. Accordingly, a second Norwegian-Swedish expedition set out the following year under the leadership of Dr. Natascha Heintz of the Norwegian Polar Institute.

If the members of the 1960 field conference were surprised by their discovery of these large dinosaurian footprints in Spitsbergen, it is fair to say that since then paleontologists throughout the world have been deeply astonished.

IguanodonIguanodon was a dinosaur that had been known from England and northern Europe, where nu­merous skeletons and some footprints had been un­earthed and described during the past century and a half. To find indications of this large dinosaur in Spits­bergen meant that in early Cretaceous time there must have been some sort of land connection between what is now an Arctic island and the European continent.

What is of particular importance is that this discovery extends the range of any dinosaurs far north of previ­ous limits. The spot where the tracks were found is only about 800 miles from the North Pole. Before this discovery, the most northerly records for dinosaurs had been about 2500 miles from the Pole. It had long been known that dinosaurs were spread across the globe during Cretaceous times, but the discovery in Spitsbergen extended their northern range to much greater limits than previously suspected.

The northward extension of Cretaceous dinosaurs, interesting though it was in widening the recorded range of these reptiles during the height of their evolutionary development, raises certain questions about the environ­ment and climate in which they lived.

We may assume, if our knowledge of modern reptiles has any bearing on reptiles long extinct, that the giant dinosaurs of Mesozoic times were tropical and subtropical animals. We may also assume that dinosaurs, like modern rep­tiles, were animals having no internal temperature con­trols; their body temperatures supposedly were closely correlated with the temperatures of their environments. If these assumptions are correct, the dinosaurs must have lived in tropical and subtropical climates, as do modern crocodiles. Certainly they were far too large to burrow underground to escape cold winters, as liz­ards and snakes do. So it seems probable that the foot­prints of large dinosaurs were made, and their bones were buried, in lands of perpetual summer.

Consequently, the discovery of Iguanodon tracks in Spitsbergen reinforced and even extended the idea, long held by many geologists and paleontologists, that the Cretaceous world was largely tropical.

Mild climates allowed large dinosaurs to exist from the tips of the southern continents and from Australia through the middle latitudes and north into what is now Canada and northern Eurasia. It would seem to have been a world in which there were no polar ice caps and in which there were probably poorly defined temperature zones. If there were any cool regions as we know them, they must have been toward the Poles.

Spits­bergenBut there is a problem. Iguanodon evidently was a plant-eating dinosaur that consumed large amounts of vegetation to maintain its great bulk. Plants, however, require daily amounts of sunlight in order to flourish. And in Spitsbergen, located halfway between the Arc­tic Circle and the North Pole, the Sun does not rise at all for four months during the winter. Thus with Spits­bergen at its present location Iguanodon could not have found food there during a third of each year, even if the climate was considerably milder than it is today.

How is such a paradox to be explained? Modern dis­coveries have confirmed the theory of conti­nental drift, which supposes that the present land masses were once combined into a single ancestral con­tinent, Pangaea, which split into fragments that drifted through time to their present positions. According to this theory, the Spitsbergen area was once a part of the Eurasian land mass that drifted north toward the end of Cretaceous time. When Iguanodon lived, the Spits­bergen area may have been located far enough south to have sufficient daylight to provide the plant life it needed for food.

In recent years the complementary theory of "polar wandering" or "polar motion" has attracted much attention and gained many adherents. The study of magnetism in rocks seems to indicate that in former geologic ages the poles were not situated where they are now. According to some authorities the North Pole at the time of the dino­saurs was at a point in northern Siberia. In this case, Spitsbergen would have been located roughly in the same latitude as present-day Oslo and Stockholm- again, far enough south for plant life to provide food. Thus the theories of continental drift and polar wan­dering coincide with the evidence we have of a warmer Earth during Cretaceous time to explain how dinosaurs could have lived on Spitsbergen.

Iguanodon was first described in 1825 by Gideon Mantell, a rather eccentric physician-scientist, who spent much of his life collecting and studying fossil bones from the Wealden beds in southern England. To Mantell, the bones of the Weald revealed an England of ancient ages quite unlike the England of 19th-century days-one of tropical aspect, inhabited by gigantic reptiles. Through the years this concept has been extended by the successors of Mantell until today it encompasses the world. And it has grown by the accu­mulation of separate discoveries, one by one, and year after year. The Spitsbergen footprints constitute one of the most interesting studies that began al­most two centuries ago. They extend the tropical environments of Cretaceous time, and take us back to a vanished world.