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Sauropod neck flexibility limits

From: Ben Creisler

New in PLoS ONE:

Matthew J. Cobley, Emily J. Rayfield & Paul M. Barrett (2013)
Inter-Vertebral Flexibility of the Ostrich Neck: Implications for
Estimating Sauropod Neck Flexibility.
PLoS ONE 8(8): e72187.

The flexibility and posture of the neck in sauropod dinosaurs has long
been contentious. Improved constraints on sauropod neck function will
have major implications for what we know of their foraging strategies,
ecology and overall biology. Several hypotheses have been proposed,
based primarily on osteological data, suggesting different degrees of
neck flexibility. This study attempts to assess the effects of
reconstructed soft tissues on sauropod neck flexibility through
systematic removal of muscle groups and measures of flexibility of the
neck in a living analogue, the ostrich (Struthio camelus). The
possible effect of cartilage on flexibility is also examined, as this
was previously overlooked in osteological estimates of sauropod neck
function. These comparisons show that soft tissues are likely to have
limited the flexibility of the neck beyond the limits suggested by
osteology alone. In addition, the inferred presence of cartilage, and
varying the inter-vertebral spacing within the synovial capsule, also
affect neck flexibility. One hypothesis proposed that flexibility is
constrained by requiring a minimum overlap between successive
zygapophyses equivalent to 50% of zygapophyseal articular surface
length (ONP50). This assumption is tested by comparing the maximum
flexibility of the articulated cervical column in ONP50 and the
flexibility of the complete neck with all tissues intact. It is found
that this model does not adequately convey the pattern of flexibility
in the ostrich neck, suggesting that the ONP50 model may not be useful
in determining neck function if considered in isolation from
myological and other soft tissue data.

original dissertation

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