However, we know with certainty what they looked like thanks to a very generous chaos spirit whose pony-transformation is strictly equus-like. At my request, he allowed me to sketch and study him. I noted the differences between him and his wife Fluttershy, and their son Larkspur. Larkspur, being half draconequus, could also transform into an equus. It was remarkable how even in pony form, Larkspur resembles his father in physique. The way traits are passed is truly perplexing, and this will require more studies. I also compared him to Princess Twilight Sparkle, an alicorn who was more than delighted to assist in my research. Despite her height, equus-Discord towered over her. She expressed a clear attraction to this form, becoming uncharacteristically flustered in his presence at the humorous dismay of his wife and son.
I’ve discovered some remarkable characteristics of ponies and equus alike from this experience. One, Discord had no horns nor wings to speak of. I initially thought this to be a coincidence, but it turns out that no known fossils of Equus have wings or horns, nor do they even have bone casings at the forehead or between the shoulders where the “magic stone” glands are found in modern ponies. It seems that these “stones” are found exclusively in the hips, just like in modern Earth ponies. At first I thought that this was simply due to Equus having a propensity toward Earth Pony magic where most magical power is focused in the back legs and hooves. However, Discord could clearly preform Unicorn spells including telekinesis, transfiguration and illusion. How can this be without a focusing point (ie horn)? Magic as we know it requires this, and Discord could simply be a special case because of his chaotic godlike nature, but this ought to be investigated. What was also fascinating was his glowing cutie mark, which transformed into different symbols as he cast spells. I imagine this is a Discord-only situation, but this had led to my current hypothesis that ponies used to exhibit magic through their cutie marks, or something of this nature.”
-excerpt from The Pony (vol 8) by Prince Janus