Triceratops is a genus of plant-eating, horned dinosaur. There are two species of Triceratops: T. Horridus and T. Prorsus. Triceratops lived between 68 million and 66 million years ago during the Late Cretaceous period. The name Triceratops is of Greek origin and means “three-horned face.” Triceratops remains are among the most abundant dinosaur fossils found, though this is more true in the United States than in Canada. In 1921, paleontologist Charles M. Sternberg found the first Triceratops fossil from Canada, discovered in southern Saskatchewan. Paleontologists have also discovered Triceratops fossils in Alberta. (See also Dinosaurs Found in Canada.)
Triceratops is a member of the Ceratopsidae family, a group of large, horned dinosaurs. Male and female Triceratops cannot be distinguished from each other in the fossil record, suggesting they had only subtle physical differences.
Adult individuals measured between 8 and 9 m long and weighed as much as 5–9 metric tonnes. Triceratops had two horns above its eyes, a parrot-like beak and a smaller horn on its snout. The larger horns measured almost 1 m. A frill measuring up to 2 m ran along the back of its skull, framing its face. Paleontologists believe the frill was for protection, recognizing their species and to attract mates (see Palaeontology). The two species of Triceratops, which paleontologists believed evolved one into the other, differed in terms of their facial ornamentation. T. Horridus, the older of the two species, had a small nasal horn and long beak, while T. Prorsus had a long nasal horn and shorter beak.
A Triceratops’ head weighed about 450 kg and accounted for up to a third of its body length. Strong limbs supported its iconic tank-like body, with the shorter front limbs having three hooves and the back limbs four.
The preserved skin of a Triceratops shows it had scales up to 10 cm across, though most scales were smaller. Triceratops had teeth designed for shearing plant matter. These teeth were arranged in up to 40 columns, known as batteries, with 3–5 teeth vertically stacked in each column. Its mouth could hold as many as 800 teeth, with new ones pushing the worn ones out.
Triceratops’ diet consisted mostly of low-lying foliage such as ferns, cycads and palms, all of which were abundant vegetation at the time. (See also Fossil Plants.) It used its beak-like mouth to grasp food and its powerful limbs and bulky body helped it take down whole trees.
Range and Habitat
As a herbivore, Triceratops did not stray far from the wetlands, rivers and streams where it grazed and nested. In Canada, paleontologists have found Triceratops fossils in Alberta and Saskatchewan. ( See also Dinosaurs Found in Canada.) They have also been found in the United States, in Wyoming, eastern Montana, North Dakota, Colorado and South Dakota.
While some dinosaurs travelled in groups, there’s no evidence suggesting this was true for Triceratops. Paleontologists have only discovered solitary individuals, with the exception of three juveniles discovered in Montana in 2005. Their remains were deposited at the same time, suggesting they were travelling or living together when their lives ended.
Reproduction and Development
Although no Triceratops eggs have been discovered, most paleontologists believe that all dinosaurs reproduced by laying eggs (see Dinosaur Eggs).In general, dinosaur eggs took 3–6 months to hatch and juvenile dinosaurs a year or more to reach sexual maturity.
Young Triceratops had little stubs for horns. The horns curved backwards, and twisted and lengthened as the juvenile grew. As Triceratops grew the horns would straighten, reaching up to 1 m in length.
For a long time, paleontologists believed that the horns and frills of ceratopsids were used for defence against predators like tyrannosaurs (see Dinosaurs Found in Canada). While there is no evidence that these species fought, there is evidence to suggest that Triceratops fought each other. In a 2009 study, paleontologists examined injury patterns on Triceratops fossils, concluding that the species used their cranial ornamentation both to engage in combat with one another as well as for visual display.
A large Triceratops fossil called Big John, found in South Dakota in 2014, also supports this theory. Bone samples from its neck frill show signs of injury and regrowth. Moreover, the shape of its injury, which occurred at least six months before Big John died, suggests it was caused by a Triceratops.
Discovery and Evolution
An American fossil collector named George Lyman Cannon is often credited as being the first to discover a Triceratops fossil, a pair of horns attached to a skull plate, near Denver, Colorado, in 1887. He sent the horns to Othniel Charles Marsh, a professor of vertebrate paleontology at Yale University. Marsh identified the partial remains as a prehistoric bison. A year later, John Bell Hatcher discovered a more complete skull in Wyoming, causing Marsh to change his mind and identify the species as Triceratops.
Paleontologist Charles M. Sternberg discovered the first Triceratops specimen from Canada in 1921, which he found while working for the Geological Survey of Canada in southern Saskatchewan. Years later, in 1946, Sternberg also discovered the first Triceratops fossil from Alberta, found in the Edmonton Formation (now known as Horseshoe Canyon Formation).
In 2014, a group of researchers looked at evolutionary changes in over 50 Triceratops skulls from the Hell Creek Formation in Montana. They correlated the placement of the fossils in the rock with structural changes in the skulls. The skulls of T. Horridus came exclusively from lower layers of rock, while the skulls of T. Prorsus came from the upper layers. Skulls from the middle layers had characteristics of both species of Triceratops, suggesting that one species evolved into another over a period of 1–2 million years.