Description and Classification

Yehuecauhceratops was a medium-sized ceratopsian dinosaur, estimated to be about 3 meters (10 feet) in length. Like other ceratopsians, it was a four-legged herbivore with a stocky body, a prominent bony frill at the back of its skull, and a powerful beak for cropping vegetation. Its skull featured a relatively short, somewhat flattened and roughened nasal horn or boss (a bony lump) over its nose. Unlike some of its larger relatives like Triceratops, Yehuecauhceratops appears to have lacked large brow horns above its eyes; if present, they were very small.

Yehuecauhceratops belongs to the family Ceratopsidae, specifically within the subfamily Centrosaurinae. Centrosaurines typically had more prominent nasal horns or bosses and shorter frills compared to their chasmosaurine relatives, which often had longer frills and more developed brow horns. The discovery of Yehuecauhceratops is important because it represents a centrosaurine from the southern part of Laramidia, helping scientists understand how these dinosaurs differed across various geographic areas. It shares some features with other centrosaurines like Avaceratops and Nasutoceratops, but possesses its own unique combination of traits, particularly in its frill ornamentation.

Distinguishing Features

Yehuecauhceratops can be identified by several key characteristics:

• A short, somewhat flattened, and irregularly textured nasal horn or boss.
• Very small or absent postorbital horns (brow horns).
• A relatively wide and short frill (the bony shield at the back of the skull).
• Unique ornamentation on the rear edge of its frill, specifically two prominent hornlets (epiparietals) that curved distinctly forwards and slightly outwards.
• Its presence in the southern region of Laramidia (now Mexico), indicating a distinct local evolution of ceratopsian dinosaurs.

Paleoenvironment and Diet

Fossils of Yehuecauhceratops were found in the Aguja Formation, dating to the late Campanian stage of the Late Cretaceous. During this time, the area in Coahuila, Mexico, was a warm and humid coastal plain environment, with rivers, swamps, and estuaries located near the edge of the Western Interior Seaway, a large inland sea that once divided North America.

Yehuecauhceratops shared this dynamic ecosystem with a variety of other dinosaurs. These included hadrosaurs (duck-billed dinosaurs) like Velafrons and Kritosaurus, other ceratopsians such as the chasmosaurine Agujaceratops, and various small theropods. Larger predators, possibly tyrannosaurids, also roamed the area. The waters were home to turtles, crocodilians, and fish. As an herbivore, Yehuecauhceratops would have used its sharp beak to snip off low-growing plants like ferns, cycads, and early flowering plants. It had powerful dental batteries (densely packed teeth) in its jaws to grind up tough plant material.

Significance and Ongoing Research

The discovery of Yehuecauhceratops is significant because it enhances our understanding of ceratopsian dinosaur diversity and distribution, particularly in the southern parts of Laramidia. It suggests that distinct groups of dinosaurs may have evolved in different regions of the continent, a concept known as faunal provincialism. The unique features of Yehuecauhceratops, especially its frill ornamentation, provide new clues about the evolution of the elaborate display structures in horned dinosaurs and how different species recognized each other.

Ongoing research continues to focus on finding more complete specimens of Yehuecauhceratops. More fossil material would allow paleontologists to better understand its full anatomy, growth stages, and individual variation. Further comparative studies with other centrosaurines will help to clarify its exact position within the ceratopsian family tree and shed more light on the evolutionary relationships between northern and southern Laramidian horned dinosaurs. Continued exploration of the Aguja Formation and similar deposits in Mexico also promises to reveal more about the unique prehistoric ecosystems of this region.