Edmontonia (Ankylosaurs)

[brandonc@advant.com (Haist, Brandon)]

I have recently read that Edmontonia may have used its shoulder spines for
intraspecific fighting, such as a deer or other antlered creature may.  The
spine is said to be bifurcated, and would lock when two Ankylosaurs got into
a "shoving" match.  Also a few other species may have followed this
behavior.  Two other theories for spinen use are 1) use could have been
secondary sexual charactoristics, or 2) the spines and outstanding armor may
have been used to "grade" the strength of the particular animal.  Does any
of these theories have more support over the others?
~Brandon Haist