Fossil | Research & Encyclopedia Articles

Fossil

Fossils are the remains, traces or impressions of prehistoric organisms. There are wholly intact animals which have been preserved such as the wooly mammoth (discussed below) or the thousands of species of insects caught up in the resins of ancient pine trees and preserved in the yellow-orange translucent fossil-bearing material amber. Prehistoric humans which fell into bogs have been preserved intact. Other fossils are produced by replacement of organic matter by inorganic matter. The inorganic replica is preserved in rock (petrified). The petrification process may be so subtle that microscopic examination, especially of petrified plants, reveals fine cellular structure. Footprints and preserved fecal material, while not actual remains of preexisting animals, are considered to be fossils because they were made by living animals. Footprints reveal something of the weight of the animal, length of stride, and whether it was bipedal or if it moved on all four feet. The diet of prehistoric animals may be revealed, in part, by examination of fossil feces known as coprolites. Unfortunately, far from all preexisting organisms are known. Many plant and animals have soft bodies and it would be extremely unlikely if they would be preserved down through the ages. Thus, little is known of literally thousands of organisms that lived in the past. Another disappointment when looking at the fossil record is that the overwhelming majority of fossils are incomplete fragments of organisms. Charles Robert Darwin (1808-1882) knew full well the inadequacy of the record of preexisting life--he referred to fossils as a multivolume history of life, but unfortunately, there are only a few volumes remaining. And, here and there, only a chapter has been preserved, and often, many of the pages are blank. The Darwinian evaluation of the incompleteness of the fossil record of 1859 still holds.

An example of elegantly preserved fossils are the wooly mammoths. They were huge elephant-like animals found in many parts of the world including North America. They lived during the Pleistocene which ended approximately 10,000 years ago. The reason that we know so much about these enormous fossils is that many of them lived in areas permanently frozen. Thus, when a mammoth would fall into, or be trapped, in an icy crevasse or meet some other fate that resulted in an icy tomb, the animal would be frozen and remained as such until it was discovered thousands of years later. The preservation was so good that the plants of the last meal could sometimes be identified and the muscle (meat) was occasionally still red thereby providing a meal for sled dogs. The Siberian mammoths had extremely long tusks which were so abundant that they were traded on the medieval markets. Mammoths are extinct now but they existed at the same time as prehistoric humans. Cave dwellers depicted masses of mammoths which witnesses to both the former abundance of these titanic fossil mammals as well as to the artistic ability of prehistoric humans.

Of course, fossil mammoths are of relatively recent origin. So too are some human fossils. The fact that they are far from ancient does not diminish their interest to paleontologists. As mentioned above, we can learn about what plants were in the diet of extinct mammoths by examining digestive system contents. This enhances the understanding of the environment of these great beasts. Recent human fossils are similarly interesting. For instance, some humans whose bones were discovered from a diversity of locations in Europe and North America are believed to have suffered during life from the malignancy (cancer) known as multiple myeloma. Paleopathologists believe that holes found in skulls and other bones, with sharply defined borders and which appear to be punched out, are strong evidence of multiple myeloma. The fossils are estimated to be as much as 5,000 years old. No one knows for certain what the contemporary risk factors are for this human malignancy but exposure to petroleum products and radiation have been suggested as possibly involved in causation. Paleontologists, and cancer epidemiologists as well, would suggest that other factors may be important to the causation of multiple myeloma due to the dearth of petroleum industry, diagnostic X-rays, nuclear power plants and nuclear explosions 5,000 years ago. However, multiple myeloma is thought to be not uncommon in fossil humans which suggests alternative risk factors. Other human cancers, generally associated with bone because of bone durability, are known from antiquity. It is well that this be remembered when it becomes all too easy to blame cancer in modern humans because of industry or the stress of modern life.

As interesting as frozen carcasses of ten millennia ago, or evidence of cancer in humans thousands of years ago are, it should be emphasized that they are not the primary focus of much of the research that has attended the study of fossils. Ancient fossils provide scholars with considerable insight into a diversity of subjects including climatology, geography, geology and evolution. Examples: Ancient plant and animal fossils gives information about the climate when they existed as living beings. Modern coral reefs occur in tropical or semitropical areas where the water remains warm throughout the year. It seems reasonable to suspect that sites of fossil coral reefs are places where the temperature remained warm. The presence of fossil corals, accompanied by other fossil invertebrates known to live in the sea, permits the mapping of ancient oceans. Ancient geography was indeed dissimilar to the geography of today. A vast ocean extended from the Gulf of Mexico to the Arctic Ocean thereby cleaving the North American continent into two great land masses. The geological study of fossils has shown that similar fossils are found in sedimentary rock throughout the world. It is also known that the oldest fossils are found deepest and newer fossils are found in more superficial layers. Any one particular site is unlikely to have all of the layers of sedimentary rock that are known. However, age can be estimated by the examination of the fossils in the particular layers that are present. Finally, even though it is incomplete, the fossil record is a testament to the fact of evolution. Some groups of animals evolved into many species, many of which still survive. In contrast, the fossil record contains many examples of organisms that flourished in the past but are no longer present.