Joseph Fielding Smith teaches that Adam was the first man on this earth; as a result, this "does away with the false notion that there were pre-Adamites."
Joseph Fielding Smith, Doctrines of Salvation, 3 vols. (Salt Lake City: Bookcraft, 1954), 1:77-78
ADAM: FIRST MAN AND FIRST FLESH. After the fall, which came by a transgression of the law under which Adam was living, the forbidden fruit had the power to create blood and change his nature and mortality took the place of immortality, and all things, partaking of the change, became mortal. Now I repeat, the account in Genesis one and two, is the account of the physical creation of the earth and all upon it, but the creation was not subject to mortal law until after the fall. It was, therefore, a spiritual creation and so remained until the fall when it became temporal, or mortal.
There was no living thing upon the earth until it was prepared for living life. The Pearl of Great Price does not say that man was the first living thing on the earth, but that he was the first flesh and the first man also. He became the first mortal flesh when he fell. By flesh is meant mortality, and Adam was the first mortal on the earth; but animals and other forms of life were placed on earth first, and he was not on the earth until everything was prepared for him. Since Adam was the first man on the earth, that does away with the false notion that there were pre-Adamites.