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The
Fossil Record & A
History of Life on Earth
Part 3 of 5
The French anatomist George Cuvier established as fact the revolutionary
idea of extinction. It is said that Cuvier could identify the remains
of an organism from just a few bones. Several people were key to
ordering fossils chronologically and thus building a history of life
on Earth.
The Industrial Revolution helped catalyze our understanding of
fossils and the history of life on Earth. Large machines used for
digging coal, making railroad beds and canals removed great volumes
of earth exposing many rock layers and their fossils. William Smith
(1769-1839), a British engineer, was in charge of building the
Somerset Canal. Smith came to realize that fossils exhibited a
regular pattern in different strata. Thus Smith could recognize
a particular rock layer from the combination of fossils present.
This observation allowed Smith to predict the locations of different
rock layers making him more efficient and successful when surveying
for canal construction. Smith was able to map out the succession
of fossils found in different rock formations. His geologic maps
showed that life forms appear and disappear through time.
At about the same time George Cuvier and Alexandre Brongniart (1770-1847),
a French naturalist and geologist, were mapping the Paris Basin.
In reconstructing the changing sea levels of the Atlantic Ocean Brongnairt
and Cuvier showed that fossils had been layed down during alternating
fresh and salt-water conditions thus establishing the fact that there
existed a succession of fossils in different formations representing
different environments.
Cuvier noticed that the more ancient a fossil the less it resembled
present day organisms. In ordering fossils chronologically Cuvier,
like Smith, was constructing a history of life on Earth using geologic
strata. Thus began the science of
biostratigraphy. Cuvier recognized mass extinctions, but believed
they resulted from regional catastrophes. James Hutton (1726-1797)
a Scottish geologist, and later Charles Lyell (1797-1875), another
Scottish geologist, reasoned that current geological processes are
the same as those that have shaped the Earth in the past, a concept
called uniformatarianism. Uniformatarianism firmly took supernatural
explanations out of geology. The idea that fossils show change through
time was well accepted by the 1840’s.
One of the chief legacies of these 19th century efforts is the geological time scale. The present day scale or column divides geologic time into intervals separated from each other by changes in rock type and abrupt changes in fossil groups.
Bibliography for Echoes of Life Through Time
Jenkins-Jones, S., Random House Webster's Dictionary of Scientists. New York: Random House, 1997.
Jones, S., Darwin's Ghost: The Origin of Species Updated. New York: Random House, 2000.
Kirk, G.S. & Raven, J.E., The Presocaratic Philosophers: A Critical History with a Seclection of Texts. Cambridge University Press, 1973.
Miller, K.R., Finding Darwin's God: A Scientist's Search for Common Ground Between God and Evolution. New York: Harper Collins, 1999.
Milner, R., The Encyclopedia of Evolution: Humanity's Search for Its Origins. New York: Facts on File, 1990.
Palmer, D., Atlas of the Prehistoric World. New York: Random House, 1999.
Prothero, D.R., Brining Fossils to Life: An Introduction to Paleobiology. New York: McGraw-Hill, 1998.
Stanley,
S.M., Extinction. New York: Scientific American Books,
1987.