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Crocodilian bite force study
From: Ben Creisler
A new paper in PLoS ONE:
Erickson, G.M., Gignac, P.M., Steppan, S.J., Lappin, A.K., Vliet,
K.A., et al. (2012)
Insights into the Ecology and Evolutionary Success of Crocodilians
Revealed through Bite-Force and Tooth-Pressure Experimentation.
PLoS ONE 7(3): e31781.
Crocodilians have dominated predatory niches at the water-land
interface for over 85 million years. Like their ancestors, living
species show substantial variation in their jaw proportions, dental
form and body size. These differences are often assumed to reflect
anatomical specialization related to feeding and niche occupation, but
quantified data are scant. How these factors relate to biomechanical
performance during feeding and their relevance to crocodilian
evolutionary success are not known.
We measured adult bite forces and tooth pressures in all 23 extant
crocodilian species and analyzed the results in ecological and
phylogenetic contexts. We demonstrate that these reptiles generate the
highest bite forces and tooth pressures known for any living animals.
Bite forces strongly correlate with body size, and size changes are a
major mechanism of feeding evolution in this group. Jaw shape
demonstrates surprisingly little correlation to bite force and
pressures. Bite forces can now be predicted in fossil crocodilians
using the regression equations generated in this research.
Critical to crocodilian long-term success was the evolution of a high
bite-force generating musculo-skeletal architecture. Once achieved,
the relative force capacities of this system went essentially
unmodified throughout subsequent diversification. Rampant changes in
body size and concurrent changes in bite force served as a mechanism
to allow access to differing prey types and sizes. Further access to
the diversity of near-shore prey was gained primarily through changes
in tooth pressure via the evolution of dental form and distributions
of the teeth within the jaws. Rostral proportions changed
substantially throughout crocodilian evolution, but not in
correspondence with bite forces. The biomechanical and ecological
ramifications of such changes need further examination.