Old Earth Ministries Online Dinosaur Curriculum
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Lesson 70 - Triceratops, Part 2
Although Triceratops are commonly portrayed as herding animals, there is currently little evidence that they lived in herds. While several other genera of horned dinosaurs are known from bonebeds preserving bones from two to hundreds or thousands of individuals, to date there is only one documented bonebed dominated by Triceratops bones: a site in southeastern Montana with the remains of three juveniles. It may be significant that only juveniles were present.
|Side view of T. horridus skeleton cast, Senckenberg Museum. (Picture Source)|
For many years, Triceratops finds were known only from solitary individuals. However, these remains are very common; for example, Bruce Erickson, a paleontologist of the Science Museum of Minnesota, has reported having seen 200 specimens of T. prorsus in the Hell Creek Formation of Montana. Similarly, Barnum Brown claimed to have seen over 500 skulls in the field. Because Triceratops teeth, horn fragments, frill fragments, and other skull fragments are such abundant fossils in the Lancian faunal stage of the late Maastrichtian (late Cretaceous, 68 to 65 mya) Stage of western North America, it is regarded as among the dominant herbivores of the time, if not the most dominant
Triceratops was one of the last ceratopsian genera to appear before the Cretaceous-Tertiary extinction event. The related Torosaurus, and the more distantly related diminutive Leptoceratops, were also present, though their remains have been rarely encountered.
Dentition and diet
Triceratops were herbivorous, and because of their low head, their primary food was
Triceratops teeth were arranged in groups called batteries, of 36 to 40 tooth columns, in each side of each jaw with 3 to 5 stacked teeth per column, depending on the size of the animal. This gives a range of 432 to 800 teeth, of which only a fraction were in use at any given time (tooth replacement was continuous and occurred throughout the life of the animal). They functioned by shearing in a vertical to near-vertical orientation. The great size and numerous teeth of Triceratops suggests that they ate large volumes of fibrous plant material, with some suggesting palms and cycads, and others suggesting ferns, which then grew in prairies.
Functions of the horns and frill
There has been much speculation over the functions of Triceratops' head adornments. The
Early on, Lull postulated that the frills may have served as anchor points for the jaw muscles to aid chewing by allowing increased size and thus power for the muscles. This has been put forward by other authors over the years, but later studies do not find evidence of large muscle attachments on the frill bones.
Triceratops were long thought to have possibly used their horns and frills in combat with predators such as Tyrannosaurus, the idea being discussed first by C. H. Sternberg in 1917 and 70 years later by Robert Bakker. There is evidence that Tyrannosaurus did have aggressive head-on encounters with Triceratops, based on partially healed tyrannosaur tooth marks on a Triceratops brow horn and squamosal; the bitten horn is also broken, with new bone growth after the break. Which animal was the aggressor is not known. Tyrannosaurus is also known to have fed on Triceratops. Evidence for this includes a heavily tooth-scored Triceratops ilium and sacrum.
In addition to combat with predators using horns, Triceratops are classically shown engaging each other in combat with horns locked. While studies show that such activity would be feasible, if unlike that of present-day horned animals, there is disagreement about whether they actually did so. Additionally, although pitting, holes, lesions, and other damage on Triceratops skulls (and the skulls of other ceratopsids) are often attributed to horn damage in combat, a recent study finds no evidence for horn thrust injuries causing these forms of damage (for example, there is no evidence of infection or healing). Instead, non-pathological bone resorption, or unknown bone diseases, are suggested as causes. However, a newer study compared incidence rates of skull lesions in Triceratops and Centrosaurus and showed that these were consistent with Triceratops using its horns in combat and the frill being adapted as a protective structure, while lower pathology rates in Centrosaurus may indicate visual rather than physical use of cranial ornamentation, or a form of combat focused on the body rather than the head. The researchers also concluded that the damage found on the specimens in the study was often too localized to be caused by bone disease.
The large frill also may have helped to increase body area to regulate body temperature. A similar theory has been proposed regarding the plates of Stegosaurus, although this use alone would not account for the bizarre and extravagant variation seen in different members of the Ceratopsidae. This observation is highly suggestive of what is now believed to be the primary function, display.
The theory of their use in sexual display was first proposed by Davitashvili in 1961 and has gained increasing acceptance since. Evidence that visual display was important, either in courtship or in other social behavior, can be seen in the fact that horned dinosaurs differ markedly in their adornments, making each species highly distinctive. Also, modern living creatures with such displays of horns and adornments use them in similar behavior. A recent study of the smallest Triceratops skull, ascertained to be a juvenile, shows the frill and horns developed at a very early age, predating sexual development and thus probably important for visual communication and species recognition in general. The large eyes and shortened features, a hallmark of "cute" baby animals, also suggest that the parent Triceratops may have cared for its young.
Depiction in recent popular media
The distinctive appearance of Triceratops has led to them being frequently depicted in films, computer games and documentaries, including the Don Bluth film The Land Before Time, which featured a young Triceratops as a main character, the 1993 film Jurassic Park and the 1999 BBC television documentary Walking with Dinosaurs. Triceratops (the species are not identified) is the official state fossil of South Dakota, and the official state dinosaur of Wyoming.
A recurring theme, especially in children's dinosaur books, is a climactic showdown or battle between Triceratops and Tyrannosaurus. In 1942, Charles R. Knight painted a mural incorporating a confrontation between the two dinosaurs in the Field Museum of Natural History for the National Geographic Society, establishing them as enemies in popular thought. Paleontologist Bob Bakker said of the imagined rivalry between Tyrannosaurus and Triceratops, "No matchup between predator and prey has ever been more dramatic. It's somehow fitting that those two massive antagonists lived out their co-evolutionary belligerence through the very last days of the very last epoch of the Age of Dinosaurs."
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