What unique ornamentation defines the posterior edge of the Xenoceratops frill, setting it apart from ceratopsids featuring fenestrae?

A pair of prominent, solid bony structures often described as large, rounded bosses

The most distinguishing characteristic of Xenoceratops is the nature of its neck frill termination. Unlike many contemporaries that utilized fenestrae—large openings in the parietal bones used to reduce weight—Xenoceratops possessed solid bone in this region. Specifically, the rear edge of the frill was adorned with a pair of highly prominent, solid bony structures. These structures are frequently detailed as large, rounded bosses or lumps. This solid configuration represents a distinct evolutionary specialization within the Centrosaurinae, suggesting different biomechanical loads or visual signaling strategies compared to fenestrated frills.