Do you know what the parents were or do you have pictures of that one as a hatchling? It could be Tremper Murphy's Patternless or it could be an APTOR. I don't think there's any way to tell from just looking at an adult.
He also looks a bit on the thin side - not scary thin though. How big is he?
damn raptor and the sir was a tremper patternless snow engima het for raptor and i feed them thats not an adult they this one was born about june 29th i have about 20 babies from that pair