[Adaptations of the hoatzin (Opisthocomus hoazin) to leaf-eating. Morphological characteristics and functional features of its bill and hyoid apparatus].
The hoatzin remains one of the most enigmatic birds. A morphofunctional analysis of its bill and hyoid apparatus throws new light on its feeding adaptation as well as on its systematic relationships. Bony and muscular skull, rhamphotheca, palate, and hyoid apparatus were described in details. Though keeping into the general organisation pattern found among Neognathae (except Galliformes), bill and hyoid apparatus of the hoatzin displays a series of species-specific features, some unique among birds. This species appears particularly well adapted to tear of leaves and process them inside the bill before ingestion. Because of very important anatomical and thence functional differences in bill and hyoid structure, any close relationship between the hoatzin and Galliformes cannot be envisioned. Such a hypothesis would implicate a counter-selective evolutionary reversion.
Université d'Etat Lomonossov de Moscou, Vorobievi Gori 1199899, B-234 Moscou, Russie.
Léonid P
LP
Korzoun
Christian
C
Erard
Jean-Pierre
JP
Gasc
Félix J
FJ
Dzerzhinsky
D000220:Adaptation, Biological; D000818:Animals; D001502:Beak / Q000033:anatomy & histology* / Q000502:physiology; D001696:Biomechanical Phenomena; D001717:Birds / Q000033:anatomy & histology* / Q000145:classification / Q000502:physiology; D002508:Cephalometry; D005247:Feeding Behavior / Q000502:physiology*; D006928:Hyoid Bone / Q000033:anatomy & histology* / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology; D009334:Neck Muscles / Q000033:anatomy & histology* / Q000502:physiology; D018515:Plant Leaves; D012886:Skull / Q000033:anatomy & histology; D013045:Species Specificity