Sigilyph's overall design is likely based of the Nazca Lines, which are located in the Nazca Desert, Peru.
It's colours may have been inspired by ancient South/Latin American tribes such as the Aztecs, Mayans or even by Aboriginal cultures located in Australia and New Zealand.
EDIT: Oh okay, nevermind. I missed the part with dirkac talking about Umbreon resembling Anubis. I thought you meant Sigilyph. Sorry! Well I'll leave my original post up anyway for a little bit of general knowledge to anyboy who cares to read :P.