"Latter-day revelation teaches that there was no death on this earth before the Fall of Adam. Indeed, death entered the world as a direct result of the Fall (2 Ne. 2:22; Moses 6:48)."
The church says that Adam lived about 6000 years ago.
Most Geology and Paleontology scholars estimate that the dinosaurs died 65 million years ago.
So if there was no death before 7000 years ago, where did all the dinosaurs come from?
|LDS Seminary Old Testament Timeline|
Prior to the 1980's it was commonly taught in church settings that fossilized dinosaur bones are from dinosaurs that lived on other worlds that were destroyed to create the Earth. They were living creatures, but not from this Earth. The did not die HERE, so there was no "death before the fall"
The Church has backed away from this teaching but the doctrine still continues to be taught among the congregations.
1987 Ensign Article on Fossils
Blog Post on Dinosaurs
Bruce R. McConkie Speech from 1980
FairMormon - Dinosaurs