Ether 9:19 in the Book of Mormon mentions elephants:
And they also had horses, and asses, and there were elephants and cureloms and cumoms; all of which were useful unto man, and more especially the elephants and cureloms and cumoms.
This is curious because it has long been thought that elephants were not found in Mesoamerica. However discoveries after the publication of the Book of Mormon prove otherwise.
Ludwell Johnson wrote in 1952:
Discoveries of associations of human and proboscidean remains [Elephantine mammals, including, elephants, mammoths, and mastodons] are by no means uncommon. As of 1950, MacCowan listed no less than twenty-seven” including, as noted by Hugo Gross, a “partly burned mastodon skeleton and numerous potsherds at Alangasi, Ecuador…There can no longer be any doubt that man and elephant coexisted in America…. Probably it is safe to say that American Proboscidea have been extinct for a minimum of 3000 years– Ludwell H. Johnson, “Men and Elephants in America,” The Scientific Monthly 75 (1952), 220-221.
How would Joseph Smith have known that elephants would be a perfect fit in the Book of Mormon?