Image:Tyrannosaurus, Frankfurt Museum. Age: approximately 70 million years.
From the current (2017) publication of the LDS Bible Dictionary. Topic: ‘Death’:
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).
22 And now, behold, if Adam had not transgressed he would not have fallen, but he would have remained in the garden of Eden. And all things which were created must have remained in the same state in which they were after they were created; and they must have remained forever, and had no end.
48 And he said unto them: Because that Adam fell, we are; and by his fall came death; and we are made partakers of misery and woe.
From the current (2017) publication of the LDS Bible Dictionary. Topic: ‘Chronology of the Old Testament:
4000 B.C. — Fall of Adam
Bible Dictionary. Topic: ‘Chronology of the Old Testament’ – LDS.org
Bible Dictionary. Topic: ‘Death’ – LDS.org
2 Nephi 2:22 – LDS.org
Moses 6:48 – LDS.org
Conflicts with Science – Mormon Think