Product Code Database
Ceratopsia or Ceratopia ( or ; Ancient Greek: "horned faces") is a group of herbivore, beaked that thrived in what are now North America, Asia and Europe, during the Cretaceous Period, although ancestral forms lived earlier, in the Late Jurassic of Asia. The earliest known ceratopsian, Yinlong downsi, lived between 161.2 and 155.7 million years ago.Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix. The last ceratopsian species, Triceratops prorsus, became extinct during the Cretaceous–Paleogene extinction event, .
Triceratops is by far the best-known ceratopsian to the general public. It is traditional for ceratopsian genus names to end in " -ceratops", although this is not always the case. One of the first named genera was Ceratops itself, which lent its name to the group, although it is considered a nomen dubium today as its fossil remains have no distinguishing characteristics that are not also found in other ceratopsians.
Ceratopsians are easily recognized by features of the skull. On the tip of a ceratopsian upper jaw is the rostral bone, an edentulous (toothless) ossification, unique to ceratopsians. Othniel Charles Marsh recognized and named this bone, which acts as a mirror image of the predentary bone on the lower jaw. This ossification evolved to morphologically aid the chewing of plant matter.Holtz, Thomas R., Jr.; Rey, Luis V. (2007). Dinosaurs: the most complete, up-to-date encyclopedia for dinosaur lovers of all ages. New York: Random House. . Along with the predentary bone, which forms the tip of the lower jaw in all , the rostral forms a superficially parrot-like beak. Also, the jugal bones below the eye are prominent, flaring out sideways to make the skull appear somewhat triangular when viewed from above. This triangular appearance is accentuated in later ceratopsians by the rearwards extension of the parietal bone and squamosal bones of the skull roof, to form the neck frill.You H. & Dodson, P. 2004. Basal Ceratopsia. In: Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 478-493.
The neck frills of ceratopsids are surrounded by the epoccipital bones. The name is a misnomer, as they are not associated with the occipital bone. Epoccipitals begin as separate bones that ossification during the animal's growth to either the squamosal or parietal bone bones that make up the base of the frill. These bones were ornamental instead of functional, and may have helped differentiate species. Epoccipitals probably were present in all known ceratopsids. They appear to have been broadly different between short-frilled ceratopsids (centrosaurinae) and long-frilled ceratopsids (chasmosaurinae), being elliptical with constricted bases in the former group, and triangular with wide bases in the latter group. Within these broad definitions, different species would have somewhat different shapes and numbers. In centrosaurines especially, like Centrosaurus, Pachyrhinosaurus, and Styracosaurus, these bones become long and spike- or hook-like. A well-known example is the coarse sawtooth fringe of broad triangular epoccipitals on the frill of Triceratops. When regarding the ossification's morphogenetic traits, it can be described as dermal. The term epoccipital was coined by paleontologist Othniel Charles Marsh in 1889.
In 1888 and 1889, Othniel Charles Marsh described the first well preserved horned dinosaurs, Ceratops and Triceratops. In 1890 Marsh classified them together in the family Ceratopsidae and the order Ceratopsia. This prompted Cope to reexamine his own specimens and to realize that Triceratops, Monoclonius, and Agathaumas all represented a single group of similar dinosaurs, which he named Agathaumidae in 1891. Cope redescribed Monoclonius as a horned dinosaur, with a large nasal horn and two smaller horns over the eyes, and a large Neck frill.
Following Marsh, Ceratopsia has usually been classified as a suborder within the order Ornithischia. While ranked taxonomy has largely fallen out of favor among dinosaur paleontologists, some researchers have continued to employ such a classification, though sources have differed on what its rank should be. Most who still employ the use of ranks have retained its traditional ranking of suborder, though some have reduced to the level of infraorder.Benton, M.J. (2004). Vertebrate Palaeontology, Third Edition. Blackwell Publishing, 472 pp.
The clade Neoceratopsia is defined as "the largest clade containing Triceratops horridus, but not Chaoyangsaurus youngi and Psittacosaurus mongoliensis". By this definition, only the members of Chaoyangosauridae and Psittacosaurus are excluded from Neoceratopsia, while all more derived ceratopsians are part of this clade. A slightly less inclusive group is Euceratopsia, named and defined by Daniel Madzia and colleagues in 2021 as "the smallest clade containing Leptoceratops gracilis, Protoceratops andrewsi, and Triceratops horridus". This clade includes the family Leptoceratopsidae and all more derived ceratopsians. Leptoceratopsids are a mostly North American group of mostly small bodied and quadrupedal ceratopsians. Another subset of neoceratopsians is called Coronosauria, which is "the smallest clade containing Protoceratops andrewsi and Triceratops horridus". Coronosaurs show the first development of the neck frill and the fusion of the first several neck to support the increasingly heavy head. Within Coronosauria, two groups are generally recognized. One group can be called Protoceratopsidae and includes Protoceratops and its closest relatives, all Asian. The other group, Ceratopsoidea, includes the family Ceratopsidae and closely related animals like Zuniceratops. This clade is defined as "the largest clade containing Ceratops montanus and Triceratops horridus, but not Protoceratops andrewsi". Ceratopsidae itself includes Triceratops and all the large North American ceratopsians and is further divided into the subfamilies Centrosaurinae and Chasmosaurinae.
All previously published neoceratopsian phylogenetic analyses were incorporated into the analysis of Eric M. Morschhauser and colleagues in 2019, along with all previously published diagnostic species excluding the incomplete juvenile Archaeoceratops yujingziensis and the problematic genera Bainoceratops, Lamaceratops, Platyceratops and Gobiceratops that are very closely related to and potentially synonymous with Bagaceratops. While there were many unresolved areas of the strict consensus, including all of Leptoceratopsidae, a single most parsimonious tree was found that was most consistent with the relative ages of the taxa included, which is shown below.
Most restorations of ceratopsians show them with erect hindlimbs but semi-sprawling forelimbs, which suggest that they were not fast movers. But Paul and Christiansen (2000) argued that at least the later ceratopsians had upright forelimbs and the larger species may have been as fast as rhinoceros, which can run at up to 56 km or 35 miles per hour.
A nocturnal lifestyle has been suggested for the primitive ceratopsian Protoceratops.Longrich, N. (2010). "The Function of Large Eyes in Protoceratops: A Nocturnal Ceratopsian?", In: Michael J. Ryan, Brenda J. Chinnery-Allgeier, and David A. Eberth (eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, Indiana University Press, 656 pp. . However, comparisons between the sclerotic ring of Protoceratops and Psittacosaurus and modern birds and reptiles indicate that they may have been cathemeral, active throughout the day at short intervals.
The traditional view that ceratopsoids originated in North America was called into question by the 2009 discovery of better specimens of the dubious Asian form Turanoceratops, which may it as a ceratopsid. It is unknown whether this would indicates ceratopsids actually originated in Asia, or if the Turanoceratops immigrated from North America.
Possible ceratopsians from the Southern Hemisphere include the Serendipaceratops, known from an ulna, and Notoceratops from Argentina is known from a single toothless jaw (which has been lost).Rich, T.H. & Vickers-Rich, P. 2003. Protoceratopsian? ulnae from the Early Cretaceous of Australia. Records of the Queen Victoria Museum. No. 113. Craspedodon from the Late Cretaceous (Santonian) of Belgium may also be a ceratopsian, specifically a neoceratopsian closer to ceratopsoidea than protoceratopsidae. Possible leptoceratopsid remains have also been described from the early Campanian of Sweden.
Some species of ceratopsians, especially Centrosaurus and its relatives, appear to have been gregarious, living in . This is suggested by bonebed finds with the remains of many individuals of different ages. Like modern migratory herds, they would have had a significant effect on their environment, as well as serving as a major food source for predators.
|
|
