When you post, add the Signature-link (button on top, tenth from the right, looks like writing) at the end of your message. I'm not answering to anyone who doesn't do so. --Kuopiofi (talk) 11:15, March 2, 2016 (UTC)
For mythology, they are mainly depicted as cockatrices.
For HP, the basilisk is hatched from a chicken egg.
For RPGs, they are probably quite avian.
For Valkyrie Crusade, the basilisk isn't any type of basilisk.
For Monster Girl Encyclopedia, while feathers aren't exclusive to birds, they are never found in snakes. And feathered limbs with scaly ends may be a bird-exclusive trait.