A new biomechanical approach on cranial sutures function: The role of contact elements in linear and non-linear models

Understanding cranial sutures and how they relieve and dissipate stress is
essential to assess their role in cranial biomechanics and to develop
highly accurate predictive models. This involves examining how ontogeny
affects cranial sutures, as well as their morphology and function, and how
these changes through time may impact essential biomechanical loadings
such as chewing or direct biting. In this work we study the cranial
sutures of Crocodylus niloticus in detail using contact elements under
finite element analysis. Contact elements permit the creation of a
physical relationship between two bones that are in contact and even to
configure these relationships, e.g. in terms of movement or flexibility.
The definition of bone contacts may require linear and/or non-linear
computational solutions to attain higher accuracy. Herein, skull geometry
is tested to determine how they may be altered by different types of
contacts under various conditions. As predicted, the absence of sutures or
cranial kinesis leads to a reduction in stress distribution across the
skull, whereas sutures and cranial kinesis help the skull relieve stress
and prevent certain bones from sustaining high stress levels. The type of
contact used in individual sutures has a significant effect on the models’
outcome. Additionally, feeding behaviors significantly impact cranial
biomechanics, reflecting the influence of other variables that may be
applied to the models.  As highlighted by the results, in order
to obtain accurate results when analyzing fossil taxa, the nature of the
cranial sutures should be taken into account. Therefore, developing
predictive models based on living taxa is invaluable because it
facilitates the study of extinct taxa for which there is a lack of
information on the fibrous joints due to poor (or non-) preservation in
the fossil record.