As for determining which animals have been strangled and not drained of their blood, we must understand that the focus was on the quantity of blood remaining in the meat of the animal. It was not the fact that the animal was strangled that kept it from being eaten, but the fact that it was never drained of its blood.
The Eocene constitutes the middle part of the Paleogene period (65-23 million years ago), preceded by the Paleocene and succeeded by the Oligocene epoch (34-23 million years ago); all of these periods and epochs were part of the Cenozoic Era (65 million years ago to the present).
Recently, I was talking with a colleague at work and I mentioned that civilizations usually only last 500 years. The only problem was that I couldn't remember where I had heard that. In fact, I wasn't all that sure that I was right. I know that the Roman Empire lasted rougly 500 years but how about the Egyptians, the Chinese, the Ottomons, etc.