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n.1.(Zool.) The horney covering of the lower mandible of a bird.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in periodicals archive ?
Excessive keratin buildup was present along the caudal half to two-thirds of both rhinotheca and gnathotheca although more pronounced on the upper bill.
Air flow is greatly limited or absent when the rhinotheca and gnathotheca are held firmly opposed, which may result in decreased air exchange and hypercapnia.
Key words: fungal granuloma, gnathotheca, disseminated cryptococcosis, Cryptococcus gattii VGIIa, Cryptococcus deuterogattii, psittacine, avian, citron-crested cockatoo.
The soft tissue mass of the left lateral aspect of the gnathotheca was visible, containing an irregular focus of mineralization.
The beak abnormalities had been observed for at least 2 years and included a progressive thickening of the left side of the rhinotheca and elongation of both the rhinotheca and gnathotheca. The overgrown keratin had been managed with frequent corrective trimming.
Both the rhinotheca and the gnathotheca were markedly overgrown, and the distal third of the rhinotheca was deviated to the right.
The gnathotheca was deviated 0.2 cm laterally to the left in relation to the rhinotheca, and the left hemimandible was variably pliable.
The rhamphotheca is the keratin layer covering the beak (8) (Fig 4) and comprises the upper bill (rhinotheca), and the lower bill (gnathotheca) keratin layers.
Avian mandibular fractures should be addressed in 2 stages: repair of the bone, and repair and alignment of the gnathotheca (lower keratinized beak).
Since the upper beak had fractured, the gnathotheca had begun to elongate.
Abstract: A male thick-billed parrot (Rhynchopsitta pachyrhyncha) was diagnosed with a malignant melanoma of the mandibular beak (gnathotheca).