A regular reader, who I have been debating about scientific and philosophical issues, threw out an interesting question. Honestly, I don't know where he was going with the question itself, but I had fun answering it.
"Just a question for you; are talking snakes, and flying horses impossible? If so, why?"
A flying horse is not possible. Neither is a talking snake.
An average full size E. ferus, or common horse, weighs anywhere from 840 to 1,200 lbs. (380 to 550 kilograms). The largest flying dinosaur ever recorded is called a Quetzalcoatlus, which weighed around 100 kilograms and needed a 15 meter wingspan just to keep it in the air. As such a flying horse would need a wingspan larger than a modern jumbo jet to keep it up in the air.
Where, exactly, those mighty wings would fold up to is beyond me. This is assuming we are talking about terrestrial horses who live on earth or a planet with similar atmospheric conditions.
Additionally, the horses skeletal frame just wouldn't be able to handle the added weight of such a massive wingspan. Basically, the horse would crush itself beneath the weight of its own wings. It seems that aviation for E. ferus is just not scientifically feasible.
Meanwhile, snakes lack vocal chords, so no, they cannot speak--they never have and never will. At least not with their voices. That's a different question than a communicating and highly intelligent snake, however.
Snakes are highly sensitive to smell, vibration, and many species are known to be able to detect the infrared spectrum! Something humans cannot do naturally. The snake's sensory organs are so highly developed, that it is feasible that given an adequate evolutionary time scale for development, their tiny brains could possibly develop densely packed neuropathways, that lead to a highly intelligent snake, which would likely communicate with other intelligent snakes via something like pheromone based telepathy. At least, such a snake is theoretically possible.