The Fossil Record 57FIGURE 3.2. In some places the fossil record is very dense and continuous, with extraordinary numbers of
specimens. (A and B) The cliffs of Chesapeake Bay in Maryland are legendary for their incredibly dense
shell beds. (Photos courtesy S. Kidwell) (C) The famous Pliocene Leisey shell beds in central Florida, with
thousands of exquisitely preserved fossil shells. (Photo courtesy Warren D. Allmon, Paleontological Research
Institution)
(A) (B)
(C)
In some places, the record of fossil shells is very dense and continuous (fig. 3.2), and these
are places where paleontologists focus their attention in studying things like evolution.
They know that not every species is preserved, of course, but they have enough data to see
how evolution occurs in the groups that do fossilize.