Flip Side of the Midnight Sun
An old song runs over and over through my head: “We’re off to Alaska, land of the midnight sun!” Indeed this attractive feature of the far north attracts scores of tourists. However like many situations, this one involves good news and bad news. The good news is the endless summer days. The bad news, of course, is the endless winter nights. All living creatures thrive in the north during the summer. Plants grow quickly and animals rise their young. The winter however is not only dark, but also very cold. How, one wonders, would organisms fare there if the climate were still dark, but not cold? That’s an interesting question because there is scientific evidence for such a situation in the past. Some of the evidence is Canadian and some is American.
In Canada, in recent days, concern has been expressed about plans for an American team to excavate a “fossil forest” on Axel Heiberg Island, a mere 1100 km from the North Pole. (The issue is not whether research should be carried out, but which country should be principally involved in this pursuit.) This site is definitely unique and valuable. At the present time, any “trees” growing in that vicinity would be a mere few inches tall. The desperate winter cold and brevity of the growing season, as well as the drying wind, prevent any large woody plants from growing. Nevertheless a forest of large trees once grew on that site. The forest remains were discovered by helicopter pilot Paul Tudge in 1985. Since then more than 1000 stumps and tree trunks have been discovered. Some are more than 6 m long and up to 2.5 m in diametre. Those were big trees! The dominant species were dawn redwood (Metasequoia) and swamp cedar (Glyptostrobus). Apparently this was a forest which included oak, birch, sycamore and walnut trees. Today we see such Carolinian forests growing from tiny pockets in Ontario near Niagara, south to Georgia. The average annual temperature near the pole might have been as warm as 12 to 15 °C. That is nothing like the desperately cold conditions of the region now.
The existence of such forest remains is interesting enough, but smaller deposits of similar species are found throughout the north. However the unfossilized condition of the trees at this site is indeed astonishing. Not only the wood, but also leafy debris as well as cones and seeds, are fresh as if they were shed last season. Nevertheless scientists insist that this forest grew 45 million years ago and has been preserved ever since. There is speculation that the trees were buried in “fresh water, probably by a flood” (Edmonton Journal July 25, 1999 F3). Apparently the plant material has remained water logged, buried under shallow sediments to the present day (Edmonton Journal July 17, 1999 A6). However, once the material is removed from the ground, it soon begins to disintegrate.
The contrast between the past climate and the present polar environment with its dry climate and average annual temperature far below zero, could scarcely be imagined. Most people believe that the forest has been found where it grew. Logs could have been moved in by water but leafy debris would probably have been lost if the distance were long. Some of the stumps have roots attached, but they most likely could not have been moved more than a short distance. Everyone also agrees that the polar location means that the vicinity would have been dark for several months each year. Even if the climate were warmer than at present, how did the trees manage to grow to large sizes when they stood to lose so much stored energy just maintaining life during the dark period? Biologists are just beginning to think about these issues. It is all so interesting!
The whole situation reminds us of the state of Alaska. Large dawn redwood trees also grew there. Such plant remains have been found in association with dinosaur fossils in that state. Thus the climate must have been similar. In the Encyclopedia of Dinosaurs edited by Philip Currie and Kevin Padian, 1997, authors Thomas Rich, Roland Gangloff and William Hammer on p. 572 suggest a mean annual temperature in Alaska of 2 to 8 °C. They base this estimate on the composition of the plant community and on leaf characteristics. Despite the similar climate, scientists suggest that the dinosaurs in Alaska lived about 25 million years earlier than the forest on Axel Heiberg Island. Nevertheless there is another similarity between the Axel Heiberg site and the Colville River (Liscomb) dinosaur bone bed site on the North Slope of Alaska. At the Canadian site, the plant material is unfossilized, and at the Alaska site, the dinosaur bones are also unfossilized (Kyle Davies. 1987. Journal of Paleontology 61 #1 p. 198). Despite the remarkable condition of the Alaska dinosaur bones, which were first mistaken by a geologist for recent bison bone (Heather Pringle. 1989. Saturday Night 104 #8 p. 19), few authors refer to the condition of the bones. For example, two articles in the Encyclopedia of Dinosaurs (Currie and Padian eds.) discuss the Colville River dinosaur bone bed. One deals with polar dinosaurs and the other with dinosaur migrations. It is hard to believe that such an exciting feature of this bone bed is ignored in a book devoted to all aspects of the study of dinosaurs. There are however plenty of other issues concerning polar dinosaurs that are worthy of our attention. A decade ago, Philip Currie insisted that dinosaur remains in Alaska were a clear indication that these animals had migrated there from southern locations. But few specialists would wholeheartedly support such a view today.
Migrations or no Migrations?
The reason why we hear so much about dinosaur migrations is because so many tremendously large dinosaur bone beds have been found in western North America. Also trackways in which animals moved side by side, at a brisk pace, all in the same direction, have been interpreted as evidence of mass migrations. But why interpret a bone bed as evidence for mass migration? Initially bone beds were considered to have accumulated gradually. In this scenario, the animals preserved in the bed were not contemporaries. Instead, over a long period of time, bones were washed by sporadic floods into a common sink hole. The carcasses involved would be expected to include very old or very young animals, those most prone to mortality. However this interpretation does not work for many recently described beds that include bones of many young adults as well as juveniles and older animals. Such a collection suggests a whole herd. In that case, a sudden catastrophe must have befallen the entire herd. Since these bones are deposited in water-borne sediments, mass drowning seems the obvious explanation. And when might these animals be likely to drown altogether — one obvious answer is when a migrating herd attempts to ford a flooding river. Thus the bone bed in Alaska, which is about 200 km long and contains many dinosaurs, mostly duckbills but others as well, was included in the migration scenario. The unfavourable dark period of the area with or without cold, was thought to lend support to the migration theory. However sober reflection has suggested otherwise.
Some requirements for long distance migrations do not fit what we know about dinosaurs. For a start, migration over land is an activity which demands high levels of endurance and suitable legs. In fact at the present time few mammals and no reptiles undertake such a program. Indeed, among migrating mammals, caribou and gnu are noteworthy since they have the most energy efficient legs known. Gregory Paul, in his article in dinosaur migration (in Encyclopedia of Dinosaurs) includes a silhouette of a duckbill dinosaur and a caribou (p. 445). The implication is that caribou, in contrast to duckbill dinosaurs, are streamlined with good legs. Moreover among animal communities today, no carnivores migrate. They merely exploit migrating herbivores that move through their territory. Thus nobody expected to fina a bone bed of carnivorous dinosaurs. They would have little reason to migrate. Yet we know of a large deposit of carnivorous dinosaur bones too. This is one of the reasons why the Coelophysis bone bed in New Mexico was so exciting to scientists. See Hilde L. Schwartz and David D. Gillette (1994. Journal of Paleontology 68 #5 pp. 1118-1130). Of course bone beds and death by drowning do not necessarily mean that the animals were migrating. They may merely have been overtaken by a major calamity like a monstrous flood.
Thus as far as the Alaskan dinosaurs are concerned, Gregory Paul disparages the idea that these or any dinosaurs achieved anything like long distance treks. He further estimates that Alaskan dinosaurs would have had to proceed as much as 4500 km in each direction if they were to achieve a drastic improvement in their winter environment. It is his view that large dinosaurs might have managed at most total trips of 500 km per year. For the dinosaurs in Alaska, there would be little point in making the effort.
The significance of the Alaskan dinosaurs is therefore very much open to discussion. As authors Rich, Gangloff and Hammer suggest, “polar dinosaurs are an indisputable fact” but their discovery has produced “more questions than answers.” (p. 572) Certainly there is plenty of room for fresh thinking on the polar forests and large animal communities in the region. What happened to that climate and to the creatures living there? How widespread was the flooding? The bone beds farther south and trackways of fleeing animals would all fit into the same scenario, of flooding unparalleled by anything we see today. Was there a catastrophic flood with a dramatic change in climate shortly thereafter? Of course we would have to collapse the time estimates from tens of millions of years to a mere few thousands of years. There are good arguments for that too. For a start, the reader could review two books Grand Canyon: Monument to Catastrophe by Steven A. Austin (Institute for Creation Research) and The Young Earth by John Morris (Master Books).
In the meantime, as the days grow longer or shorter with the changing seasons, let us remember northern communities of the past. It would be expensive perhaps, but not impossible to subject dawn redwood trees and other plants in greenhouses to lengthy annual periods of darkness. Elevated carbon dioxide levels could be part of the experimental design too as this might have contributed to a warmer climate. Such experiments might provide most illuminating answers!
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