Horned dinosaurs, known scientifically as ceratopsians. These ancient creatures, whose name means “horned face,” often spark curiosity about their distinctive headgear. While many are recognized for their elaborate frills and multiple horns, the question of which dinosaurs possessed just two horns is a common one. While some ceratopsians indeed sported three horns, several other species prominently featured two brow horns.
The Prominent Horns of Triceratops
Triceratops often comes to mind first. Its name, meaning “three-horned face,” directly references its distinguishing features. This large, quadrupedal herbivore is renowned for its two substantial brow horns, positioned above its eyes, which could reach lengths of up to 3 feet in adult specimens. A smaller, blunter horn was also present on its snout.
Fossil evidence indicates Triceratops underwent changes in its horn morphology as it matured. Juvenile Triceratops possessed small, backward-curving brow horns that would straighten and then curve forward as the animal aged. These dinosaurs lived during the late Maastrichtian age of the Late Cretaceous period, approximately 68 to 66 million years ago. Their remains are particularly abundant in western North America, found in formations such as the Hell Creek and Lance Formations. Two recognized species, Triceratops horridus and Triceratops prorsus, have been identified, with T. prorsus typically having a longer nasal horn and a deeper snout compared to T. horridus.
Dinosaurs with Two Distinct Brow Horns
One such dinosaur is Nasutoceratops titusi, whose name translates to “large-nosed horned face.” This ceratopsian, discovered in Utah’s Kaiparowits Formation, lived during the Late Cretaceous period, around 76.0 to 75.5 million years ago. Nasutoceratops is characterized by its unusually large, forward-curving brow horns that have been likened to those of a Texas Longhorn bull, extending significantly from above its eyes. Its snout region was notably deep but short, setting it apart from other ceratopsids.
Another significant example is Zuniceratops christopheri, an earlier ceratopsian that provides insights into the evolution of horned dinosaurs. Found in New Mexico and dating back to the Turonian stage of the Late Cretaceous, about 90.9 to 88.6 million years ago, Zuniceratops is recognized as the earliest known ceratopsian to possess brow horns. This dinosaur had two prominent, albeit smaller, horns above its eyes, along with a nasal horn. Its discovery suggests that the lineage of horned ceratopsians may have originated in North America.
Beyond Two: The Diversity of Horned Dinosaurs
The array of horn and frill structures among ceratopsians highlights remarkable diversity, demonstrating that two brow horns represent just one of many variations. Styracosaurus albertensis, for instance, is known for its single, large nasal horn and a frill adorned with numerous long spikes. Another example is Diabloceratops eatoni, whose name means “devil-horned face.” This ceratopsian, which lived about 79.5 million years ago in Utah, featured two large, upward and sideways curving horns originating from the back of its neck frill, in addition to smaller horns above its eyes and a short nasal horn.
Other ceratopsians, like Pachyrhinosaurus, diverged even further from the typical horned appearance. Instead of a prominent nasal horn, Pachyrhinosaurus possessed a large, rough bony boss or thickened area over its snout. The diverse forms underscore the evolutionary experimentation within this group, where different horn and frill configurations developed.
Life and Times of Horned Dinosaurs
Ceratopsians were exclusively herbivorous dinosaurs, relying on plant matter for sustenance. Their powerful beaks and rows of grinding teeth were well-suited for processing tough, fibrous vegetation, such as cycads, palms, and ferns. These dinosaurs roamed the Earth primarily during the Cretaceous Period, a geological interval spanning from approximately 145 to 66 million years ago.
The horns and frills of ceratopsians likely served multiple purposes. While defense against large predators, such as Tyrannosaurus rex, is a possibility, these structures are also thought to have played a role in species recognition, display for mating, and establishing dominance within their groups. Evidence from fossil bone beds suggests that many ceratopsians exhibited social behaviors, possibly living in herds, which could have provided collective protection and facilitated foraging. These magnificent creatures, alongside most other non-avian dinosaurs, eventually vanished during the Cretaceous-Paleogene extinction event approximately 66 million years ago.