Before fossils were understood to be the actual remains of once-living plants and animals, they were regarded in some quarters as tricks of the devil, planted by the fallen one to test the fidelity of the faithful.
After all, fossils of animals that clearly lived in the ocean were found far from any modern ocean (like those fossil clams in Nebraska mentioned in an earlier post) and even on the tops of mountains.
At a time when the Earth and everything in it was understood to be unchanged from its original creation, fossils of marine invertebrates on mountain tops were problematic, and a divinely sent global flood was an explanation that conformed both to the observations and to the philosophical framework of the time.
We now understand the dynamic nature of the Earth and can explain these observations in terms of mechanisms like plate tectonics and glaciation.
Illustration: The last major transgression of the sea over North America formed a seaway that reached from the Gulf of Mexico to the Arctic during the Cretaceous Period (144-65 million years ago). From http://www.emporia.edu/earthsci/student/mcgee2/hipln005.jpg
