If a creature dies when under the effect of a polymorph ability, does it ever revert to its true form?

Say a creature has polymorphed itself. For instance, a dandasuka using its Change Shape ability. If it dies, will it naturally revert to its true form? If so, when? I don’t see any info about this in the Polymorph trait’s rules.

If there aren’t any cut-and-dry rules about this, does any official literature suggest one way or another?