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Comparative Anatomy and Biomechanics of the Feeding Apparatus of Parrots (Aves: Psittaciformes)
Author(s) -
Cost Ian N.,
Middleton Kevin M.,
Witmer Lawrence M.,
Echols M. Scott,
Holliday Casey M.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.577.7
Subject(s) - rostrum , neurocranium , anatomy , skull , bite force quotient , biology , craniofacial , quadrate bone , biomechanics , zoology , ecology , genetics , genus
Parrots occupy varied dietary niches that require an agile, mobilized but sturdy feeding apparatus. Cranial kinesis, flexibility among intracranial joints, has a central role in the unique feeding apparatus of parrots. Parrots possess a highly mobile, streptostylic quadrate that drives the kinetic assemblage by moving the rod‐like pterygoids. The pterygoids, in turn, act as levers and rostrally actuate the tall, thin palatine bones which possess a robust articulation with the rostrum. This palatomaxillary system of articulation rotates the rostrum about the synovial craniofacial hinge, leading to extensive prokinetic movement between the frontal and nasal bones. In this study we analyze the size and orientations of jaw and palatal muscles as well as the biomechanical environment of the kinetic palate of five species of parrots: Psittacus erithacus , Eclectus roratus , Brotogeris jugularis , Strigops habroptilus , and Nestor notabilis . We compared feeding apparatuses across species using 3D data derived from muscle resultants, 3D modeling, and finite element analysis to identify shared patterns of cranial form and function. We digitally mapped jaw muscles onto the models, calculated 3D moments about multiple joints using BoneLoad, and evaluated force propagation through and strain patterns in the models using finite element analysis. Quantitative muscle orientations were visualized and compared using 3D spatial orientations. These data show relationships between muscle orientations and loading of cranial elements during feeding behaviors and highlight the morphological and dietary diversity of the parrot feeding apparatus. We found a wide diversity of orientations among parrot cranial muscles, however, jaw and palate muscles in the parrot species studied are highly specialized for cranial kinesis. Our results show that parrots have appreciably altered the conservative environment of the feeding apparatus by radically expanding their range of cranial kinesis. Understanding how parrot joint articulations work in a highly mobilized system can be applied to skull biomechanics, behavior, and our understanding of avian cranial kinesis. This new understanding will be applied to parrots of various morphologies with similar diets in future studies to assess the abilities of novel morphologies in performing similar tasks. More broadly, these new methods can be applied across other vertebrates to assess morphological performance capabilities of biomechanical tasks. Support or Funding Information We thank the National Science Foundation (NSF IOS‐1457319), Missouri Research Board, Missouri Research Council, and the Department of Pathology and Anatomical Sciences for funding this research.