Most of the book probably took place in an area about 300 miles by 150 miles in southern mexico and Guatemala. I may be wrong, but I don't believe there are llamas, alpacas or bison in that area.
O.K., so you're going with this area, right?
Would this be a fair summary?
[FONT=trebuchet ms,arial,helvetica]The second and third migrations occurred circa 600
BCE, between the times of the Assyrian and Babylonian victories over the Israelites. The immigrants:
established large civilizations extending from one sea to another, wrote in Hebrew and some form of Egyptian, domesticated horses and cattle, cultivated wheat, barley and other Old World grains, traveled in chariots and smelted metals, including iron and steel.[/FONT]
So let's talk animals first. Once again, no evidence of any kind, archeological, paleontological, for pre-Columbian horses, cattle, oxen, goats in this area. Actual native fauna include: jaguars, tapirs, iguanas, howler monkeys, sloths, aquatic animals such as manatees and sea turtles. So once again the BoM names animals that were not present, and fails to name those that were.
Archeology: This is an extremely well explored area, because one of the greatest American civilizations, the Maya, lived there. Did the Maya have horses, cattle, iron, steel, wheat, barley, chariots, etc. etc.? They did not. They did not smelt any metal until after the tenth century. Nor is there any evidence of any other people in this region doing any of these things. They traded in obsidian, jade, and quetzelcoatl feathers, which, again, are not mentioned.
They used heiroglyphics which bear no resemblance or relationship to any known Egyptian system.
By confining yourself to a specific area, you reduce the possibility that "we just haven't found it yet." You're talking about a relatively small area, that has been extremely well excavated. These were good sized cities and towns, and quite a few of them, and we've found them, excavated them, and even restored some of them.
Maybe you need to get on board with the "We don't know where it was" story, because that works much better. As soon as you pinpoint a location all you have to do to verify is go there and dig. Then publish your results! Why do you suppose this hasn't happened?