Page 18 - The Restless Earth Fossils

Fossils 17

Mammoths and mastodons were similar to, but not the same as,
African elephants.
Cuvier struggled to understand why these creatures no longer
appeared to exist. He wanted to reconcile fossil discoveries with
biblical accounts of Genesis. He reasoned that one of three things
must have happened: (1) The animals must still be alive some-
where in the world; (2) the animals must have died off completely
(become extinct) for some reason; (3) older versions of animals
must have somehow changed over time to become the animals we
see today. Cuvier favored option number 2. He decided that God
must have destroyed old worlds in a series of disasters and then
built new ones—a theory called catastrophism.
In fact, all of Cuvier’s options are correct to some degree.
Every now and then, animals once thought to be extinct are
found in some remote location. In 1938, a species of fish thought
to be extinct for 70 million years, the coelacanth, was found in
an African fish market; a live specimen was later captured off the
coast of the Comoro Islands. Such creatures are often referred to
as living fossils.
In 1859, a scientist named Charles Darwin (1809–1882)
convincingly showed in his book The Origin of Species that liv-
ing things do change over time—or evolve—through a process he
called natural selection. Darwin showed how living things with
slight advantages can reproduce more effectively than other liv-
ing things, and so their genes will be passed on. Over time—huge
stretches of geological time that were becoming more and more
evident to paleontologists—small differences become very large
and noticeable.

dinosaur Madness

English country doctor Gideon Mantell (1790–1859) and his wife
Mary loved to hunt fossils. One summer day in 1822, Mary found
a fossil resembling a mammal tooth in very ancient rocks that
should not contain such fossils. Later, Mantell found teeth in a
nearby quarry that looked most similar to the teeth of iguanas—
tropical reptiles—except they were much bigger. Eventually, more

RE_Fossils2print.indd 17 3/17/09 8:58:42 AM