The report on this work concludes with the observation that "something went on here that is still difficult to explain." Some archaeologists have suggested that the horse bones were stirred upward from lower to higher levels by the action of tunneling rodents, but they admit that this explanation is not easy to accept. The statement has also been made that paleontologists will not be pleased at the idea that horses survived to such a late date as to be involved with civilized or near-civilized people whose remains are seen in the ceramic-using levels.5 Surprisingly, the Mexican researchers show no awareness of the horse teeth discovered in 1957 by Carnegie Institution scientists Pollock and Ray. (Some uncomfortable scientific facts seem to need rediscovering time and time again.)
Zak,
The horse bones were never dated themselves. What was dated was the material around the horse bones. It is not that strange for older artifacts, which were kept as precious objects by people, to be embedded in younger strata.
I linked you to the thread where this was discussed in more detail. But to repeat, the Ray reference is actually talking about equus conversidens, a horse that dates to the Pleistocene era. Yes, indeed, that is "pre-Maya", but it is within the range of already accepted dates of the existence of horses prior to their extinction. And look again at this section from the FARMS article:
In terms of their visible characteristics, those bones should have been classified as from the Pleistocene American horse species, then called Equus occidentalis L. However, Mercer decided that since the remains were near the surface, they must actually be from the modern horse, Equus equus, that the Spaniards had brought with them to the New World, and so he reported them as such.3 In 1947 Robert T. Hatt repeated Mercer's activities. He found within Actun Lara and one other cave more remains of the American horse (in his day it was called Equus conversidens), along with bones of other extinct animals. Hatt recommended that any future work concentrate on Loltun Cave, where abundant animal and cultural remains could be seen.4
Mercer acknowledged that the horse bones looked like equus occidentalis, which is already within the time range for the horse prior to its extinction in the New World. But since it was in a higher level, he decided it "must be" a modern horse. Let's give him the benefit of the doubt and conceded that he probably didn't have the benefit of the expertise and knowledge that modern Mesoamericanists now possess, so he was confused by what he had found. But now we understand that Mesoamericans often kept sacred objects - like bones, which sometimes had script written on them - and that these objects could far predate the area in which it was eventually found.
And the next section is even more damning:
Robert T. Hatt repeated Mercer's activities. He found within Actun Lara and one other cave more remains of the American horse (in his day it was called Equus conversidens), along with bones of other extinct animals.
EQUUS CONVERSIDENS dates from the Pleistocene era.
Zak, the problem is that you are so eager to believe, so eager to find evidence that reinforces your belief that you don’t approach texts with enough skepticism to do things like look up EQUUS CONVERSIDENS to figure out when this horse appeared on this continent. At least, I’m guessing that’s what you do, and that’s what the FARMS authors bank on people like you doing, because I can’t figure out how you otherwise find this evidence so impressive.