Description and Classification

Xenoceratops was a medium-sized horned dinosaur, estimated to be about 6 meters (20 feet) long and weighing around 2 tonnes (2.2 short tons). Like other ceratopsians, it was a quadrupedal herbivore with a prominent bony frill at the back of its skull and a parrot-like beak. The known fossil material of Xenoceratops primarily consists of parts of the skull, including pieces of the frill (parietals and squamosal) and a nasal bone. While complete horns have not been found, it likely possessed brow horns over its eyes and a horn or thickened bump on its nose, similar to its relatives.

This dinosaur belongs to the family Ceratopsidae, specifically within the subfamily Centrosaurinae. Centrosaurines are a group of horned dinosaurs often characterized by well-developed nasal horns or bosses, smaller brow horns (though this varies), and ornate frills with various spikes and projections. Xenoceratops is considered one of the oldest known large-bodied ceratopsids from Canada, providing important clues about the early evolution of this group. Its features suggest a close relationship to other centrosaurines like Diabloceratops and possibly an ancestor to later forms such as Centrosaurus and Styracosaurus.

Distinguishing Features

Xenoceratops is distinguished from other ceratopsians primarily by the unique ornamentation of its frill:

• It possessed two large, prominent, somewhat flattened spikes (epiparietals) located near the midline at the top edge of its frill, which curved slightly upwards and outwards.
• The sides of its frill (squamosals) were relatively less ornamented compared to some more advanced centrosaurines, though they likely had a series of smaller bumps or hornlets along their edges.
• The nasal bone shows a thickened, rugose (rough) boss, indicating the presence of a significant structure on its nose, possibly a short, stout horn or a heavily textured bump.

Paleoenvironment and Diet

Xenoceratops lived in what is now Alberta, Canada, during the Campanian age of the Late Cretaceous. The fossils were discovered in the Foremost Formation, which represents a coastal plain environment. This area was characterized by rivers, estuaries, and swamps, situated near the western edge of the large inland sea called the Western Interior Seaway. The climate was likely warm and humid, supporting a rich diversity of plant life.

As a ceratopsian, Xenoceratops was an herbivore. Its powerful beak would have been used to snip off tough plant material, such as ferns, cycads, and early flowering plants. Batteries of teeth in its cheeks would then grind this vegetation before swallowing. It likely fed on low-growing plants and shared its environment with other dinosaurs, including hadrosaurs (duck-billed dinosaurs), ankylosaurs (armored dinosaurs), and various theropods (meat-eating dinosaurs).

Significance and Ongoing Research

The discovery of Xenoceratops is significant because it represents one of the oldest known large ceratopsids in Canada and provides valuable information about the early diversity and evolution of centrosaurine dinosaurs. Its unique features help paleontologists understand how the elaborate frills and horns of these dinosaurs evolved over time. The find also highlights the potential for discovering new dinosaur species in older rock layers that have not been as extensively explored as some younger formations.

Ongoing research involving Xenoceratops focuses on further refining its anatomical details and its precise placement within the ceratopsian family tree. Comparisons with newly discovered horned dinosaurs from similar time periods help to build a more complete picture of dinosaur ecosystems in North America during the Late Cretaceous. The discovery of more complete fossil material of Xenoceratops would greatly enhance our understanding of this “alien horned face” and its role in the evolution of horned dinosaurs.