Page 153 - Lore Strikes Again

Equestria: Even the extra-planar monsters love it!

Fluttershy: Dragons don’t count as natural beasts, so my Nature skill won’t work on them.
Twilight Sparkle: That can’t be right. I checked the ENTIRE D&D Compendium, and almost every single dragon is tagged with the “natural” keyword!
Fluttershy: Um… Normally, I think that’s true. But dragons aren’t natural to Equestria.
DM: Oh. Ohhhhh. Crap, she’s right. I had completely forgotten.
Twilight Sparkle: Tell me you’re kidding.
DM: A long time ago, dragons weren’t native to this plane of existence. They originated from a harsher realm far away in the Astral Sea. It’s been many centuries since their first arrival, but dragons are still an enigma to everything in the natural plane.
Twilight Sparkle: But that doesn’t explain how she knew about this the whole time.
Fluttershy: Your familiar Spike explained it, when I first met him. Don’t you remember?