Anchiceratops (meaning "near horned face" or "long snout"[note 1][1] is a genus of extinct chasmosaurine ceratopsid dinosaur that lived during the Late Cretaceous Period of western North America. Like other ceratopsids, it was a quadrupedal herbivore with three horns on its face, a parrot-like beak, and a long frill extending from the back of its head. The two horns above the eyes were longer than the single horn on its snout, as in other chasmosaurines. Anchiceratops approached 20 feet (6 m) in length.[2]
Description[]
Size comparison with postcranium restored after NMC 8547
Like other ceratopsids, A. ornatus was a quadrupedal herbivore with three horns on its face, a parrot-like beak, and a long frill extending from the back of its head. The two horns above the eyes were longer than the single horn on its snout, as in other chasmosaurines.
Anchiceratops was a medium-sized ceratopsid. If specimen NMC 8547 is not taken into account, no very exact estimations of the body length of Anchiceratops can be given. Some popular science books state that it approached 20 feet (6 m) in length. In 2010 Gregory S. Paul, on the assumption that specimen NMC 8547 represented Anchiceratops, estimated its length at 4.3 metres, its weight at 1.2 tonnes.
Anchiceratops frills are very distinctive. Rectangular in shape, the frill is edged by large epoccipitals, which are osteoderms in the form of triangular bony projections. These are exceptionally wide and coarse. Some of these epoccipitals are on the side of the frill, formed by the squamosal; these episquamosals vary between five and nine in number. The last episquamosal is very large, approaching the size of the three osteoderms per side on the rear edge of the frill, the epiparietals. Another characteristic feature is the pair of bony knobs located on either side of the midline, towards the end of the frill. These are pointing sideways and are very variable in form and size between individuals. The parietal bone, forming the rear edge and the middle of the frill, has smaller parietal fenestrae, window-like openings, than those seen in other chasmosaurines like Pentaceratops and Torosaurus. The frill has deep arterial grooves on both the upper and the underside.
Specimen NMC 8547, on which traditionally descriptions of the postcrania of Anchiceratops have been based, has many traits that are unique in the Chasmosaurinae. The vertebral column contains seventy-four vertebrae: ten of the neck, thirteen dorsals, twelve sacrals and thirty-nine caudals. Typically chasmosaurines have twelve dorsals, ten sacrals and up to forty-six tail vertebrae. Mallon presumed that the synsacrum, the fused vertebrae supporting the pelvis, had shifted to the rear. The neck of NMC 8547 is exceptionally long, with four syncervicals, fused anterior cervical vertebrae. Also the pelvis is very long. The tail is short. The forelimbs are very robust, with a large deltopectoral crest on the humerus, indicating a heavy musculature.
Discoveries and species[]
Type specimen AMNH 5251
American paleontologist Barnum Brown named Anchiceratops in 1914, as he believed Anchiceratops was a transitional form closely related to both Monoclonius and Triceratops and intermediate between them. When the type skull was first recovered, it sported an astounding frill, but lacked part of the face.[1] There is one valid species known today (A. ornatus), whose name refers to the ornate margin of its frill. A second species was named A. longirostris by Charles M. Sternberg in 1929, but this species is widely considered a junior synonym of A. ornatus today.
The first remains of Anchiceratops were discovered along the Red Deer River in the Canadian province of Alberta in 1912 by an expedition led by Barnum Brown.[2] The holotype is the back half of a skull, including the long frill,[2] and several other partial skulls were found at the same time, which are now stored in the American Museum of Natural History in New York City. A complete skull was discovered by C.M. Sternberg in 1924 20 kilometers northwest of Morrin, Alberta, Canada,[1] and described as A. longirostris five years later.[2] This specimen had a frill that measured 1.66 meters long, much smaller than the original type specimen discovered in 1912.[1] Another specimen, collected by Sternberg in 1925 12 kilometers southwest of Rumsey, Alberta,[1] lacks the skull but is otherwise the most complete skeleton known from any ceratopsid, preserving a complete spinal column down to the last tail vertebra. Sternberg's material is now housed in the Canadian Museum of Nature in Ottawa. Other material has been found since, including one or two bonebed deposits in Alberta, but very little Anchiceratops material has been described.[1]
Fossils[]
NMC 8547 mounted at the Canadian Museum of Nature, completed with a skull cast of NMC 8535. NMC 8547 might represent a separate taxon
Most Anchiceratops fossils have been discovered in the Horseshoe Canyon Formation of Alberta, which belongs to the early part of the Maastrichtian stage of the Late Cretaceous Period (74-70 million years ago). Frill fragments found in the early Maastrichtian Almond Formation of Wyoming in the United States resemble Anchiceratops (Farke, 2004). However, pieces of a frill have been found from two localities in the older Dinosaur Park Formation (late Campanian, 78-74 million years ago) with the characteristic pattern of points seen in Anchiceratops frills. This may represent an early record of A. ornatus or possibly a second, related species (Langston, 1959). Two Anchiceratops skulls have been found in Toronto, however, these specimens have yet to be described in formal literature.[1] Fragmentary fossil skull bones have also been found in the St. Mary River Formation deposits dated to the same age as the Horseshoe Canyon Formation by Wann Langston.[1]
Frill[]
Anchiceratops frills are very distinctive. Rectangular in shape, the frill is edged by large epoccipitals (triangular bony projections), and has smaller fenestrae (window-like openings) than those seen in other chasmosaurines like Pentaceratops and Torosaurus.[2] Another characteristic feature is the pair of bony knobs located on either side of the midline, towards the end of the frill.
Classification[]
ROM 802, a skull in the Royal Ontario Museum
C.M. Sternberg originally designated a smaller skull as the new species Anchiceratops longirostris, because of its size, and also its proportionally longer snout and much shorter horns that point forwards instead of upwards. However, modern paleontologists find that the size and form of this skull falls within the range of variation seen in A. ornatus and so it is probably a member of that species.
It has been proposed that Anchiceratops is a sexually dimorphic species, where the skull of A. longirostris actually represents a female.[3] Other Anchiceratops skulls are larger and show shorter, more robust snouts, as well as much longer horns that point more vertically. This form is thought to represent the male. Sexual dimorphism is also seen in most other chasmosaurine genera, very strongly in some (Triceratops, Torosaurus, Pentaceratops), and more weakly in others (Chasmosaurus). The basal ceratopsian Protoceratops also exhibits strong sexual dimorphism (Lehman, 1990).
Paleobiology[]
Restoration
Anchiceratops is rare compared to other ceratopsians in the area, and usually found near marine sediments, in both the Horseshoe Canyon and Dinosaur Park Formations. This indicates that Anchiceratops may have lived in estuaries where other ceratopsids did not live. Flowering plants were increasingly common but still rare compared to the conifers, cycads and ferns which probably made up the majority of ceratopsian diets.
Skull cast of TMP 1983.001.0001, Geological Museum, Copenhagen
JPInstitute.com Description[]
Anchiceratops is a lesser-known member of the family of dinosaurs that includes Triceratops. It was very similar in looks to its more famous cousin, except that its frill was not solid and it was squarer shaped. Anchiceratops also had shorter horns and was a little smaller than Triceratops.
Barnum Brown of the American Museum of Natural History first discovered Anchiceratops along the Red River in Alberta, Canada in 1912. This original specimen consisted of only the back part of the skull, but since that time a number of specimens have been found, including a nearly complete skeleton now at the National Museum of Canada. Anchiceratops' body was very much like other ceratopsians except that it had a very short tail. Its most distinctive feature was its strange neck frill - moderately long and rectangular with small oval openings. On the back of the frill there were six large bony knobs that expanded into short, triangular, backward pointing spikes. Anchiceratops also had two short spikes that curve up and outward. It had a short nasal horn, a very long nose, and two moderate-sized brow horns. It was probably a fairly common dinosaur in its time, as a number of fossils have been found.
Links[]
References[]
- Farke, A.A. 2004. Ceratopsid dinosaurs from the Upper Cretaceous Almond Formation of southwestern Wyoming. Rocky Mountain Geology. 39: 1-5.
- Langston, W.J. 1959. Anchiceratops from the Oldman Formation of Alberta. National Museum of Canada Natural History Papers. 3: 1-11.
- Lehman, T.M. 1990. The ceratopsian subfamily Chasmosaurinae: sexual dimorphism and systematics. In: Carpenter, K. & Currie, P.J. (Eds.). Dinosaur Systematics: Approaches and Perspectives. Cambridge: Cambridge University Press. Pp. 211-219.
- Sternberg, C.M. 1929. A new species of horned dinosaur from the Upper Cretaceous of Alberta. National Museum of Canada Bulletin. 54: 34-37.
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- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Dodson, P., 1996. The Horned Dinosaurs. Princeton: Princeton University Press. pg. 111-115.
- ↑ 2.0 2.1 2.2 2.3 2.4 "Anchiceratops." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 124. ISBN 0-7853-0443-6.
- ↑ Brown, B. 1914. Anchiceratops, a new genus of horned dinosaurs from the Edmonton Cretaceous of Alberta. With a discussion of the origin of the ceratopsian crest and the brain casts of Anchiceratops and Trachodon. Bulletin of the American Museum of Natural History. 33: 539-548.