We don't have synonyms for casques yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are casquet, casque and masques.
(n) :
A hard structure on the head of some birds, such as cassowaries, some hornbills and guineafowl, and some reptiles such as chameleons and basilisks.
(n) :
A hard structure on the head of some birds, such as cassowaries, some hornbills and guineafowl, and some reptiles such as chameleons and basilisks.