Poor fellow. His evidence doesn't support his conclusion.
Considering sheep, goats, camels, horses, cows, dogs, chickens?!?, vacuum cleaners, and at least one case of a penguin, these guys are shading the truth.
Just because this batch of bones didn't show mixed genes doesn't mean that there was a whole lot of 'breeding' going on.
(I once even had one guy come into the ER with a 'penile fracture' caused by attempting to 'breed' with a knothole in a fence board!)