A sound understanding of an organisms morphology is a prerequisite of rigorous functional analysis, but loss of morphological information is an unfortunate consequence of the process of fossilization. This loss may be limited to the decay of soft tissues, and skeletons which are robust and mineralized may be preserved complete, in three-dimensions. For fossil organisms which possessed such skeletons, collapse and flattening or disarticulation cause few problems in morphological and functional analysis, but many organisms have skeletons which lack sufficient rigidity to retain three-dimensional geometry after post mortem decay of soft tissues or during sedimentary compaction; their fossil remains, if preserved at all, are generally flattened. Similarly, skeletons made up of a number of different components held together in life by soft tissues will exhibit some degree of disarticulation and flattening (figure 1). There are also situations, typically in heavily compacted mudrocks, where even rigid skeletons that in other sedimentary settings survive almost intact are flattened.

In some cases, generally where the skeletal remains under investigation were not particularly three-dimensional in life, flattening presents few obstacles to morphological and functional analysis. But where significant three-dimensionality has been lost, investigation of functional morphology or even basic systematic work is next to impossible without attempting a reconstruction of the original three-dimensional morphology. In this chapter we will briefly review the processes by which skeletons can become flattened and the different approaches to the restoration of collapsed skeletons.