Abstract.-The most widely cited explanation for the functional enigma of sutural complexity in
ammonoids, the Buckland hypothesis, has related septal folding and fluting to buttressing, providing
increased shell strength against implosion, along with increased efficiency and decreased weight
in shell and septum construction.  In Paleozoic ammonoids, sutures ranged from simple to extremely
complex.  Comparison of sheil and septum thickness (in polished sections) with sutural complexity
in 49 Paleozoic ammonoid genera (Middle Devonian-Upper Permian) indicates that no significant
reduction in either septum thickness or shell thickness accompanied a one-hundred-fold increase
in sutural complexity.  These preliminary results fail to support the Buckland hypothesis, suggest
there may have been alternative incentives for increasing sutural complexity, and add support to
views that septal fluting may have been related to buoyancy control.