The Nature of Fossils: A Historical Perspective
Part 1 of 5
Fossils are an integral part of our culture. We encounter fossils in museums, schools, T.V., and movies. It is hard to believe that our ancestors were unsure about the nature of fossils.
Throughout recorded history there have been both naturalistic and super-naturalistic explanations for fossils. The Greeks believed mammoth fossils were the bones of human giants. Xenophanes, a Greek philosopher, hypothesized that there existed a cycle in which moisture eroded land into mud followed by another beginning. Xenophanes cited marine fossils found on land as evidence to support his ideas. Aristotle speculated that ancient fish swam into cracks in the rock and got stuck. Crinoids with star-shaped centers were believed to have been formed by falling stars and ammonites were believed to be decapitated snakes. The word fossil, which means “dug up”, was coined during the Renaissance. People wondered, are fossils pranks of nature, works of the Devil, or supernatural representations of ideal life forms? Many believed that fossils formed during Noah’s flood. Leonardo da Vinci recognized that fossil shells in the Apennine Mountains of Italy were the remains of ancient sea life and argued they could not have formed during Noah’s flood. He recognized that different specimens had been formed at different times.
Many people in Western cultures were taught to believe in a literal interpretation of the Bible. It was natural to believe every species in existence was made in a single creation event. This idea also extended to rocks, which were believed to have been formed as we see them during the first days of creation. Thus in the absence of two key concepts, extinction and sedimentary rock formation a more accurate understanding of fossils was not possible.
Robert Hooke (1635-1703) and Niels Stensen (1638-1686) would put science on a more productive path to understanding the nature and formation of fossils. Niels Stensen (Latinized to Nicholaus Steno) was an anatomist and naturalist. After dissecting present day sharks, Steno realized that the tongue stones, thought to be the tongues of dragons or snakes, must be ancient shark teeth. He also postulated that fossilized shells had been made by once living organisms. Steno thus championed an organic origin of fossils. How could solid fossils form inside solid rock? Steno hypothesized that fossils encased in rock must be older than the layers in which they are found. He also argued that this rock had once been loose and over years had hardened into sandstone. Through his paleontological studies Steno contended that sedimentary strata had been deposited in former seas.
Robert Hooke was an English scientist and inventor. Hooke made some of the first accurate illustrations of fossils. He also suggested that species may have a fixed “life span” and might be used to order rocks chronologically. Hooke like Steno championed the idea that fossils represented ancient plant and animal life. Hooke and Steno helped to jump-start the science of stratigraphy, which is the study of rock layers and their fossils. The ideas of Hooke and Steno would not be accepted for another century.
Bibliography for Echoes of Life Through Time
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Prothero, D.R., Brining Fossils to Life: An Introduction to Paleobiology. New York: McGraw-Hill, 1998.
S.M., Extinction. New York: Scientific American Books,