In his unpublished article, Combinatorial properties of triangulations of oriented matroids, Julian Webster proves that every triangulation of an oriented matroid is partitionable.
Does this result appear somewhere in the published literature? If so, where?
Edits:
Webster himself does not know if this result has been published elsewhere.
Two excellent resources for triangulations of oriented matroids are Triangulations: Structures for Algorithms and Applications in the realizable case and Triangulations of Oriented Matroids in the general case. Neither of these sources discuss partitions of triangulations of oriented matroids.
A simplicial complex $\Delta$ is partitionable if there is a function $\phi : F \to \Delta$ on the facets of $\Delta$ such that the set of intervals $\{[\phi(f), f]~|~f \in F\} $ is a partition of the faces of $\Delta$.