Varanus komodoensis feeding

["Thomas R. Holtz, Jr." <tholtz@umd.edu>]

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0026226

D'Amore DC, Moreno K, McHenry CR, Wroe S (2011) The Effects of Biting and 
Pulling on the Forces Generated during Feeding in the
Komodo Dragon (Varanus komodoensis). PLoS ONE 6(10): e26226. 
doi:10.1371/journal.pone.0026226

Abstract

In addition to biting, it has been speculated that the forces resulting from 
pulling on food items may also contribute to feeding
success in carnivorous vertebrates. We present an in vivo analysis of both bite 
and pulling forces in Varanus komodoensis, the
Komodo dragon, to determine how they contribute to feeding behavior. 
Observations of cranial modeling and behavior suggest that V.
komodoensis feeds using bite force supplemented by pulling in the 
caudal/ventrocaudal direction. We tested these observations using
force gauges/transducers to measure biting and pulling forces. Maximum bite 
force correlates with both body mass and total body
length, likely due to increased muscle mass. Individuals showed consistent 
behaviors when biting, including the typical
medial-caudal head rotation. Pull force correlates best with total body length, 
longer limbs and larger postcranial motions. None of
these forces correlated well with head dimensions. When pulling, V. komodoensis 
use neck and limb movements that are associated with
increased caudal and ventral oriented force. Measured bite force in Varanus 
komodoensis is similar to several previous estimations
based on 3D models, but is low for its body mass relative to other vertebrates. 
Pull force, especially in the ventrocaudal
direction, would allow individuals to hunt and deflesh with high success 
without the need of strong jaw adductors. In future
studies, pull forces need to be considered for a complete understanding of 
vertebrate carnivore feeding dynamics.

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>From the Conclusions:

lthough the V. komodoensis behavior model is unique amongst extant taxa, it can 
shed light upon the feeding behaviors of extinct
ziphodont tetrapods, especially theropods [34], [47]. Supposedly some theropods 
also had relatively low bite forces given their size
and cranial morphology [1]. As in V. komodoensis, such low bite forces may have 
been supplemented by a strong pull and would not
hinder the animal's ability to modify flesh. Both tooth mark data and cranial 
morphometrics suggest that theropods used caudally
oriented force during feeding [47]-[49]. Modeled neck musculature implies that 
some theropods (i.e. Ceratosaurus and Allosaurus)
also displayed significant ventroflexion, suggesting the "pulling" or "raking" 
of ziphodont teeth through the use of these
postcranial muscles [50].

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA