Triceratops skeleton on the river's edge  Chicago Academy of
Sciences  How Dinosaurs Became Fossils  The term fossilized is
important. It is not the dinosaur bones themselves that
paleontologists find, but their stony replicas. Fossil bones are
created by the slow replacement of bone molecules with the
molecules of minerals in ground water. This process sometimes
preserves even the delicate cell structure of the bones. Other
times the bones dissolve completely and only their imprint is
left on the rocks.  Teeth and bones are the most durable parts
of a vertebrate's body. They may survive long after the animal's
soft parts have rotted or been eaten. Except for fossilized
footprints, skeletal remains are the most common fossils.
Unfortunately, few animals ever become fossilized, compared to
the millions that lived.  Animals seldom die where they can be
fossilized. A recently deceased animal that remains above ground
will be dissolved by the chemicals in soil and converted into
plant food. This is why the bodies