These are the formidable talons of a Harpy Eagle, one of the largest species of raptor on Earth. Let them serve as a reminder that bloodthirsty dinosaurs live among us, that they are descended from downy forebears, and that, yes, feathered animals can be downright terrifying.

For reference:

Also for reference:

See also: The feet of a cassowary.

[reddit via Wil Wheaton]