Well, I reckon there are a few ways one could probably edit this and still be "grammatically correct," so it may ultimately come down to personal preference and style of the writer. Here's one (although perhaps not perfect) such attempt:

The situation in Mesoamerica contrasts strongly in that the area provided only two domesticable animals (the turkey and the dog) whose meat yield was far lower than that of cows, sheep, goats, and pigs. Corn, Mesoamerica's staple grain, was as I have already explained, difficult to domesticate and perhaps so to develop.

I have to admit that the "so to develop" does not make a whole lot of sense. Perhaps "so" is a typographical error and means something else (such as it did not produce quickly enough)? One could use a semi-colon after "pigs," since they are two independent clauses, but I just thought it would be cleaner to end the sentence and begin another.

Hey, even if I'm wrong and don't win a fabulous prize, there's always an addition to the old post count. Holy Gunsmoke - I can't believe I even went there.

Did anyone catch that obscure reference to another popular thread on this board?