casque

plural casques

1. A helmet.

   He beheld his child dashed to pieces, and almost buried under an enormous helmet, an hundred times more large than any casque ever made for human being, and shaded with a proportionable quantity of black feathers.

   1764, Horace Walpole, The Castle of Otranto, section I

2. A hard structure on the head of some birds, such as cassowaries, some hornbills and guineafowl, and some reptiles such as chameleons and basilisks.

   Helmeted Hornbill, Rhinoplax vigil (CR): Restricted to the Thai-Malay Peninsula, Sumatra and Borneo, this is the only hornbill species whose casque is solid keratin and therefore carvable.

   2015, James Eaton et al., “Trade-driven extinctions and near-extinctions of avian taxa in Sundaic Indonesia”, in Forktail, page 2, column 2

   2 more examples

   Smooth Casque-headed Basilisk – Cutete Policía . . . A flat-topped cephalic casque projects over the neck in this species. The posterior edge of this casque is smooth without projecting spines. . . Its vernacular name, cutete policía, is in allusion to the flat casque, said by some to resemble the service cap worn by Guatemalan police.

   1998 Campbell, Jonathan A. Amphibians and reptiles of Northern Guatemala, the Yucatán, and Belize p. 154-155. ISBN: 0-8061-3064-4

   . . . the Southern Cassowary . . . has a double red wattle that hangs from its blue-skinned neck, while a horn-like casque adorns its head. Although it is often described as horny or bony, the casque has a core of firm foamy material, riddled with cells and canals, and covered by a spongy layer and a tough, keratinous, outer sheath. Its purpose is unknown, but one possibility is that it is for sexual attraction. Another is that it protects the skull as the bird bashes its way, head lowered, through the bush when running. Other suggestions are that it is used as a weapon in dominance disputes, or as a tool to push aside leaf litter during foraging. Observations of behaviour lend little support to any of these proposals.

   2011 Penny Olsen and Leo Joseph: Stray Feathers CSIRO Publishing Australia ISBN: 9780643103450

3. biologySynonym of galea.

   Synonyms: galea