Research by John Sorenson has attempted to answer the question of whether the "horse" (Enos 1:21) in the Book of Mormon is merely a matter of labeling by analogy some other quadruped with the name Equus (the true horse), or whether the scripture's use of "horse" refers to the actual survival into very recent times of the American Pleistocene horse (Equus equus). If, as most zoologists and paleontologists assume, Equus equus was absent from the New World during Book of Mormon times, could deer, tapir, or another quadruped have been termed "horses" by Joseph Smith in his translating? Sorenson has suggested the latter possibility and has pointed to archaeological specimens showing humans riding on the backs of animal figures, some of which are evidently deer. Also Mayan languages used the term deer for Spanish horses and deer-rider for horsemen. Indians of Zinacantan, Chiapas, believe that the mythical "Earth Owner," who is supposed to be rich and live inside a mountain, rides on deer. In addition, the Aztec account of the Spanish Conquest used terms like the-deer-which-carried-men-upon-their-backs, called horses. Another explanation has been to hold that true horses which are well-documented for the late glacial age in America, survived into Book of Mormon times.
Excavations at the Post Classic site of Mayapan in Yucatan in 1957 yielded remains of horses in four lots. Two of these specimens are from the surface and might have been remains of Spanish animals. Two other lots, however, were obtained from excavation in Cenote [water hole] Ch' en Mul "from the bottom stratum in a sequence of unconsolidated earth almost 2 meters in thickness." They were "considered to be pre-Columbian on the basis of depth of burial and degree of mineralization. Such mineralization was observed in no other bone or tooth in the collection although thousands were examined, some of which were found in close proximity to the horse teeth.
In southwest Yucatan, Mercer found horse remains in three caves associated with potsherds and other artifacts, and with no sign of fossilization. Excavations of 1978 at Loltun Cave in the Maya lowlands turned up further horse remains.
A careful study of the reported remains . . . still remains to be done. . . . But in the meantime, the few references to horses in the Book of Mormon should not be counted as erroneous or unhistorical. [John Sorenson, "Once More: The Horse," in Reexploring the Book of Mormon, F.A.R.M.S., pp. 98-100] [See the commentary on Alma 18:9]