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Erlikosaurus (therizinosaur) bite force

From: Ben Creisler

A new online paper:

Stephan Lautenschlager (2012)
Cranial myology and bite force performance of Erlikosaurus andrewsi: a
novel approach for digital muscle reconstructions.
Journal of Anatomy (advance online publication)
DOI: 10.1111/joa.12000

The estimation of bite force and bite performance in fossil and
extinct animals is a challenging subject in palaeontology and is
highly dependent on the reconstruction of the cranial myology.
Furthermore, the morphology and arrangement of the adductor muscles
considerably affect feeding processes and mastication and thus also
have important dietary and ecological ramifications. However, in the
past, the reconstruction of the (cranial) muscles was restricted to
the identification of muscle attachment sites or simplified computer
models. This study presents a detailed reconstruction of the adductor
musculature of the Cretaceous therizinosaur Erlikosaurus andrewsi
based on a stepwise and iterative approach. The detailed,
three-dimensional models of the individual muscles allow for more
accurate measurements of the muscle properties (length, cross-section,
attachment angle and volume), from which muscle and bite force
estimates are calculated. Bite force estimations are found to be the
lowest at the tip of the snout (43–65 N) and respectively higher at
the first (59–88 N) and last tooth (90–134 N) position. Nevertheless,
bite forces are comparatively low for E. andrewsi, both in actual
numbers as well as in comparison with other theropod dinosaurs. The
results further indicate that the low bite performance was mainly used
for leaf-stripping and plant cropping, rather than active mastication
or chewing processes. Muscle and thus bite force in E. andrewsi (and
most likely all therizinosaurs) is considerably constrained by the
cranial anatomy and declines in derived taxa of this clade. This trend
is reflected in the changes of dietary preferences from carnivory to
herbivory in therizinosaurs.