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Title: Feeding kinematics and morphology of the alligator gar ( Atractosteus spatula , Lacépède, 1803)
Abstract

Living gars are a small clade of seven species that occupy an important position on the actinopterygian phylogenetic tree as members of Holostei, sister‐group to teleosts, and exhibit many plesiomorphic traits used to interpret and reconstruct early osteichthyan feeding mechanisms. Previous studies of gar feeding kinematics have focused on the ram‐based, lateral‐snapping mode of prey capture found in the narrow‐snoutedLepisosteusgenus, whereas this study focuses on a member of the broad‐snoutedAtractosteussister‐genus, the alligator gar (Atractosteus spatula, Lacépède, 1803). High‐speed videography reveals that the feeding system of alligator gars is capable of rapid expansion from anterior to posterior, timed in a way to generate suction, counteract the effects of a bow‐wave during ram‐feeding, and direct a unidirectional flow of water through the feeding system. Reconstructed contrast‐enhanced μCT‐based cranial anatomy and three‐dimensional modeling of linkage mechanics show that a lateral‐sliding palatoquadrate, flexible intrasuspensorial joint, pivoting interhyal, and retractable pectoral girdle increase the range of motion and expansive capabilities of the alligator gar feeding mechanism. Reconstructions of muscular anatomy, inferences from in vivo kinematics, and in situ manipulations show that input from the hyoid constrictors and hypaxials play an important role in decoupling and modulating the dual roles of the sternohyoideus during feeding: hyoid retraction (jaw opening) and hyoid rotation (pharyngeal expansion). The alligator gar possesses an intricate feeding mechanism, capable of precise control with plesiomorphic muscles that represent one of the many ways the ancestral osteichthyan feeding mechanism has been modified for prey capture.

 
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PAR ID:
10372569
Author(s) / Creator(s):
 ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Journal of Morphology
Volume:
280
Issue:
10
ISSN:
0362-2525
Page Range / eLocation ID:
p. 1548-1570
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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