Ceratopsidae

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Ceratopsidae
Live reconstruction of Triceratops

Live reconstruction of Triceratops

Temporal occurrence
Upper Cretaceous ( Campanium to Maastrichtian )
83.6 to 66 million years
Locations
Systematics
Pelvic dinosaur (Ornithischia)
Cerapoda
Marginocephalia
Ceratopsia
Neoceratopsia
Ceratopsidae
Scientific name
Ceratopsidae
Marsh , 1890

The Ceratopsidae (also Ceratopidae ) are a group of dinosaurs within the Ceratopsia .

They were large, quadruped (moving on all fours) animals, characterized by their horns on their nose and above their eyes and their neck shield. As far as we know today, these were probably used to identify and deal with conspecifics and less to ward off enemies. With their tooth batteries (teeth arranged in a row, which were replaced by the next tooth when worn), these dinosaurs were well adapted to a plant-based diet. The Ceratopsidae are known almost only from the late Upper Cretaceous (around 83 to 66 million years ago) in western North America , where they achieved a great diversity of species in a short geological period. The only known exception is the Sinoceratops , which was only described in 2010 and found in what is now China .

During the mass extinction at the end of the Cretaceous Period , like all non-avian dinosaurs, they became extinct. There are two subfamilies, the Centrosaurinae and the Chasmosaurinae .

features

General

The Ceratopsidae were the largest representatives of the Ceratopsia. They reached lengths of four to eight meters and a weight of several tons. They were sturdy animals with strong limbs, the hind legs being significantly longer than the front legs.

Although some genera are only known from individual finds, there have been numerous finds of the skull and trunk skeleton of many taxa . Fossil remains of the trunk skeleton are rarer, of some genera such as Arrhinoceratops and Diceratus only the skull is known.

skull

Skull of Pentaceratops with the rostral bone at the tip of the upper jaw and the predental in front of the lower jaw

As with all Neoceratopsia, the skull of the Ceratopsidae was very large and massive. Including the neck shield, it reached over two meters in Pentaceratops and Torosaurus , which is the longest known skull of all land-dwelling animals. Viewed from above, it was almost triangular, with the pointed muzzle and the wide cheek region giving shape. As with all Ceratopsia, the tip of the snout was formed from the rostral bone (in front of the upper jaw) and the predental (in front of the lower jaw). The wrinkled surface of the rostral bone could indicate that it was surrounded by a layer of keratin . In the Centrosaurinae, the rostral bone was approximately triangular laterally (viewed from the side), in the Chasmosaurinae, however, it was significantly more elongated and curved downwards. The predentale was curved upwards at the front and ended in a pointed point that rests against the rostral bone. The cutting edge of the Praedental was flat in the Chasmosaurinae and laterally curved in the Centrosaurinae.

Centrosaurus skull : As with most Centrosaurinae, the nasal horn is long, but the over-eye horns are missing.
Skull of Anchiceratops with the short nasal horn customary for the Chasmosaurinae and strongly elongated outer horns

The intermaxillary bone (premaxillary) behind the rostral bone was very high and one of the most formative elements of the facial skull. The nostrils were clearly enlarged and almost round. In the Chasmosaurinae there was a presumably air-filled cavity in the intermaxillary bone, which was missing in the Centrosaurinae. The tear bone (lacrimale) was reduced in the Ceratopsidae, as was the fenestra antorbitalis (the skull window in front of the eye socket). The nasal bone carried a bony hump, which was often elongated to a nasal horn and was probably coated with keratin. In many Centrosaurinae the nasal horn was long, it reached up to 50 centimeters in Styracosaurus . In Einiosaurus it was noticeably curved forward, in some Centrosaurinae such as Achelousaurus and Pachyrhinosaurus it was transformed into a thickened hump. The nasal horns of the Chasmosaurinae are uniformly short.

The super-eye horns were outgrowths of the postorbital , which also formed the back edge of the eye socket and part of the cheek. In the Centrosaurinae, the over-eye horns were small and reached a maximum of 15 centimeters in length, sometimes they were transformed into indentations or small bones. With the Chasmosaurinae they were well developed except for Chasmosaurus and could be over a meter long in the larger representatives.

The expansive cheek region was heavily modified. Jugale , quadratojugale and quadratum are pushed into one another, the fenestra infratemporalis (the lower cranial window of the temporal region ) was shifted downwards and greatly reduced in size. Another bone, the epijugale, formed conspicuous cheek horns in some species such as Pentaceratops , while in others it is inconspicuous. The fenestra supratemporalis (the upper cranial window of the temporal region) was formed from the postorbital, the parietal bone (parietal) and the squamous bone (squamosum). A feature only present in the Ceratopsidae is a cavity behind the cranial cavity that opens through a fontanel on the back of the head. This cavity is absent in young animals and is very variable in adult animals. The function of this cavity is still unclear.

In addition to the horns, the most striking feature of the Ceratopsidae is the neck shield, which was formed from the parietal and scale bones. Its length was around 60 to 100% of the length of the actual skull. In general, the neck shields of the Centrosaurinae are short and those of the Chasmosaurinae, with the exception of Triceratops, are long. In almost all species there were paired windows in the shield, the largest in Chasmosaurus and Pentaceratops , but closed in Triceratops . The outer edge of the shield was covered with undulating ossifications called epoccipitalia . In some species, especially in the Centrosaurinae, the Epoccipitalia developed into spine-like structures that could also be directed forward.

teeth

Triceratops teeth in a skull cast in the Natural History Museum Vienna

The teeth of the Ceratopsidae consisted of tooth batteries , which are teeth arranged in rows, which were replaced by the following tooth when they were worn out. This form has developed convergent to that of the Hadrosauridae . The individual teeth were in tightly packed rows of teeth, each tooth position had three to five replacement teeth. The number of tooth positions roughly correlates with the size of the skull: 28 to 31 in Centrosaurus and 36 to 40 in Triceratops . The occlusal surfaces of the dentition were almost vertical, which suggests that the teeth were mainly used for cutting.

Trunk skeleton

As with all coronosauria, the first cervical vertebrae of the Ceratopsidae were fused to form the syncervical , although it is disputed whether this was formed from the first three or four cervical vertebrae. The six cervical vertebrae behind were short and wide. Thereafter there were 12 free vertebrae , up to three further vertebrae were fused with the four sacral vertebrae and the first three caudal vertebrae to form the sacrum. The tail of the Ceratopsidae was long, but the exact number of caudal vertebrae is only known in a few cases. So it was at Anchiceratops 38 or 39 wherein Styracosaurus contrast, 46 in Pentaceratops obtained 28, the last is so small that could be available as five other any more. The tail was stiffened by chevron bones (Y-shaped appendages on the underside of the caudal vertebrae).

Skeleton of triceratops

The limbs of the Ceratopsidae were robustly built, the fore limbs were shorter than the hind limbs, as in almost all dinosaurs, and only reached around 70% of their length. In the larger species, the long bones had greatly enlarged ends with a rough surface and thus resembled those of the sauropods . This could be a sign of thick cartilage tissue . In the smaller species, the ends of the long bones are less pronounced and the surface is smooth.

In the shoulder girdle of Ceratopsidae the relatively large is coracoid (coracoid) striking that in adult animals with the shoulder blade merged. The collarbones were never found. The humerus was longer than the spoke . The front foot was always smaller than the rear foot and built short and wide. It ended in five toes, the first three of which ended in blunt hooves and the last two in bony knobs.

In the pelvis of the Ceratopsidae, the ilium was long and deep, the prepubis protruded just as far forward as the ilium. The pubic bone (pubis) was very short and the ischial (ischium) is robust and bent, especially at the Chasmosaurinae. The femur was always longer than the shin . The hind foot was short and strong and ended in four toes with blunt hooves .

Integument (skin)

Fossilized remains of the Centrosaurus integument

In several finds of Ceratopsidae, remains of the integument (skin) can be seen. In Chasmosaurus part of the pelvic region is known, here the skin was covered with large, round plates with a diameter of up to 55 millimeters. The plates ran in irregular rows and became smaller towards the belly. The large plates were separated from each other by around 50 to 100 millimeters, the spaces between them were covered with small, irregularly shaped plates. Another finding of the skin on the thigh of Centrosaurus shows a similar pattern, only here the large plates were further apart.

Variance and gender dimorphism

Since there are numerous fossil remains of many genera, the variance within a taxon can be better compared than with other, lesser-known dinosaurs. There are around 50 completely or partially preserved skulls from Triceratops, some of which differ slightly from one another. These differences have resulted in 16 species of the genus Triceratops being described. Today's view is based on the assumption that it is a question of intraspecific variations, and combines all finds into one or at most two species.

Related to this and also connected with the search for the function of the horns and neck shields is the question of a sexual dimorphism in the Ceratopsidae, i.e. whether there were differences in body structure between males and females. Such sexual dimorphism has been found in several dinosaurs, including Protoceratops , an ancient ancestor of the Ceratopsidae. Various low sexual dimorphisms have also been postulated in the Ceratopsidae, mainly in the area of ​​the horns and the neck shield. Even if two morphs can be distinguished within a taxon , it cannot be clearly stated whether this is due to sexual dimorphism, to several species or to an intraspecific variation. Accordingly, there is no unequivocal evidence for a sexual dimorphism in the Ceratopsidae - neither in body size nor in the construction of the headdress.

Paleobiology

Social behavior and habitat

Fossil remains of Ceratopsidae mostly come from individual animals, but there are also numerous bone beds in which the often dismembered bones have been found by dozens, sometimes even thousands, of individuals. Such bone beds are known, for example, from Anchiceratops , Centrosaurus , Chasmosaurus , Einiosaurus , Pachyrhinosaurus and Styracosaurus , but not from Triceratops , one of the most common Ceratopsidae. These bone beds almost always contain the remains of a single species and are composed of the remains of young animals, subadult (half-grown) and adult animals, while individual finds mostly come from adult animals.

Finds of remains of several animals in one place do not necessarily have to indicate a group life, but can also be due to deposition technology . It is also conceivable that during periods of drought, many otherwise solitary animals would come together at watering holes and die there due to the spring's drying up. In fact, rock investigations from the Ceratopsidae period indicate a dry, seasonally strongly fluctuating climate .

Statements about the social behavior of the Ceratopsidae are accordingly difficult and it cannot be assumed that all species lived in groups. The investigations of the mass deposits, however, lead to the conclusion that some species formed associations with conspecifics for at least part of the year.

There are also still uncertainties about the preferred habitat. In general, however, they are more likely to have inhabited open habitats . Some research suggests that these animals were more common in coastal areas than inland. D. Brinkmann et al. consider a migration behavior to be conceivable. As a result, they may have lived alone or in small groups in coastal areas and then banded together in large herds, possibly in the context of reproduction.

Function of the horns and neck shields

The different forms of the horns of the Ceratopsidae (here Styracosaurus ) speak against the fact that their main function was defense.

Several hypotheses have been put forward regarding the function of the horns and neck shields. The most common one assumes that they were used to defend against predators. The horns are shock weapons and the shields protect the neck from being bitten. The main predators in this scenario are the Tyrannosauridae , especially the " Late Cretaceous All-Star Game " between Tyrannosaurus and Triceratops is a popular motif in popular dinosaurs. But this hypothesis has some weaknesses: If defense were the main motive for the development of these head outgrowths, not every Ceratopsidae genus would have developed its own shape of horns and shields, some of which would be useless or even counterproductive, such as the regression of the over-eye horns in many Centrosaurinae or the hook-shaped spines on the edge of the Centrosaurus shield . In addition, the shields were very thin, often measuring less than 2 millimeters. In addition, they were equipped with windows and provided with numerous blood vessels and therefore hardly suitable as protection against neck bites.

Another hypothesis sees the neck shield as a starting point for a greatly enlarged masticatory muscles . Morphological reasons speak against it: The fenestra supratemporalis (the upper cranial window of the temporal region ) is relatively small, and a smooth area next to it has already been identified as the starting point of the masticatory muscles, and the structure of the surface of the shields speaks against it. Ultimately, it is doubtful whether a masticatory muscle over a meter long would actually have brought an evolutionary advantage, since lengthening a muscle does not strengthen it to the same extent.

A third hypothesis, first formulated by Wheeler in 1978, sees the horns and shields as tools for thermoregulation . This view is based on the signs of numerous blood vessels in these structures combined with the increase in surface area - the neck shield could be more than a square meter. Although the thermoregulation hypothesis is not implausible, it does not explain the strong morphological differences between the individual genera.

Arrows indicate (healed) bone lesions on two skulls of Triceratops caused by fighting (from Farke et al. 2009). Scale 10 cm

A fourth hypothesis, first formulated by L. Davitashvili in 1961, says that the horns and neck shields were used for communication and the discussion about territories or mating partners. This view is supported by the fact that the individual taxa often only differed in the construction of the horns and shields. As a result, the characteristics may have played a crucial role in how the individual species recognized each other. Another point is - as finds from young animals show - that these characteristics were only fully developed after reaching adult size, i.e. only at the point in time when the fight for territories or mating partners began. Some stab wounds in the cheek region and the shields could be traced back to fights with conspecifics. In connection with the presumed at least temporary formation of larger herds, a scenario can be anticipated in which the display of protruding heads, threatening gestures or fights between conspecifics played a role, in which it was a question of contests for territories, the mating privilege or the formation of rankings. A 2009 investigation found many wounds in the shields of Triceratops compared to few wounds in Centrosaurus . This finding suggests that Triceratops used its horns in fights with conspecifics, while with Centrosaurus the display could have been the main function (or the thrusts were directed against other body parts).

It is quite conceivable that the horns and neck shields served several purposes, and apart from the point of attachment for a disproportionate masticatory muscles, all of the hypotheses presented above could apply. In analogy to animal species living today, the hypothesis of identifying and dealing with conspecifics is considered to be the most plausible based on current knowledge.

Posture and locomotion

Mounted skeleton of Triceratops : the kinked front legs with the humerus bones held almost horizontally should not correspond to the actual posture.

The question of the posture and locomotion of the Ceratopsidae has turned out to be difficult to answer. Many old drawings as well as the first skeletal structures ( Triceratops 1904 and Chasmosaurus 1923) showed the animals with upright, vertical hind legs and widely spread, kinked forelegs, with the humerus being held almost horizontally. The reasons for this were probably the structure of the head, the humerus and the raven bone. Later studies, for example by Robert Bakker , however, came to the conclusion that the Ceratopsidae kept the front legs vertical and columnar. Anatomical research contradicted this and advocated a semi-erect position of the front legs with the elbows slightly bent outwards . In addition to anatomical examinations, Ichnofossils (fossilized footprints) were also used. Paul and Christiansen came to the conclusion that these animals had their front legs almost straight, i.e. parallel to the longitudinal plane of the body ( parasagittal ), and with only slightly angled elbows.

Equally controversial is the question of how and at what speed these animals could move. Due to their presumed high weight and their massive, rather short limbs, they are more likely to be considered clumsy, slow animals. According to the calculations of RA Thulborn, they could reach a speed of 25 km / h. Paul and Christiansen come to the assumption that they were capable of a locomotion similar to the gallop and could reach a speed similar to that of the rhinos (over 40 km / h).

food

Ceratopsidae had a pointed snout - presumably for selective feeding - and tooth batteries with vertical occlusal surfaces.

The construction of the jaws of the Ceratopsidae with the tooth batteries with a vertical occlusal surface is unique among vertebrates. This specialization is the same for all Ceratopsidae and has not changed in the development history of these dinosaurs. The teeth were aligned for a cutting, not grinding, motion. The temporomandibular joint was deeper than the row of teeth and the muscle process (coronoid process) on the lower jaw branch was enlarged and provided the starting point for what was probably very strong masticatory muscles, all of which indicates that these animals have a high bite force. The narrow, pointed snout, which the Ceratopsidae had in common with all Ceratopsia , is commonly regarded as a sign of selective feeding. It should have been more suitable for grabbing and plucking, but not for biting off.

Possibly they had an enlarged digestive tract with symbiotic microorganisms for better utilization of the difficult to digest plant food. For example, a multi-chambered stomach (as in ruminants ) or an enlarged intestinal tract (as in odd-toed ungulates ) are conceivable .

Since the head was kept close to the ground, they probably ate mainly herbaceous plants . It is also conceivable that they bent down or broken off higher plants with their horns and beaks. However, it is not clear which plants they ate exactly. Because of their large size, dental batteries, and possible tendency to form larger herds, they have likely consumed inferior, high fiber plants. Cycads and palms are often adopted as the main food. However, fossil remains of these plants are rarely found in the rock layers from which the Ceratopsidae are known. It is therefore conceivable that ferns played an important role in the nutrition of the Ceratopsidae. Coe et al. believe it is possible that there were real fern prairies that fed these animals.

Reproduction and development

Head of a young triceratops : the horns and neck shield are significantly smaller than those of adult animals

Compared to other dinosaurs, relatively little is known about the reproduction and individual development of the Ceratopsidae. Like all dinosaurs, they laid eggs, but so far there are no egg finds that can be clearly assigned to the Ceratopsidae. Neither have nests or hatchlings been brought to light so far.

Based on the findings in the mass deposits, Sampson et al. three age levels can be identified: juvenile (adolescent), subadult (half-grown) and adult (fully grown). It turns out that the distinguishing features in the area of ​​the horns and neck shields only emerged in the adult animals. Accordingly, it is very difficult to distinguish the juveniles of different genera from one another - at least the Centrosaurinae, the group studied. Sampson et al. therefore advocate using taxa that have only been described on the basis of fossil finds of juvenile animals ( Brachyceratops and Monoclonius ) as the Nomina dubia .

Systematics

External system and history of development

The Ceratopsidae are integrated within the Ceratopsia into the Neoceratopsia and here again into the Coronosauria . Their sister group is Zuniceratops , with whom they form the Ceratopsoidea, more distantly they are related to the Protoceratopsidae and Leptoceratopsidae . This is expressed in a simplified cladogram of the Ceratopsia:

 Ceratopsia  
  NN  

 Psittacosauridae


  Neoceratopsia  

 basal Neoceratopsia (e.g. Archaeoceratops )


  Coronosauria  

 Protoceratopsidae


  NN  

 Leptoceratopsidae


  Ceratopsoidea  

 Zuniceratops


   

 Ceratopsidae







   

 Yinlong



Map of North America during the "Middle" Cretaceous Period . The Ceratopsidae were essentially restricted to western North America, which was isolated from the rest of the continent by an inlet ( Western Interior Seaway ).

Whether the Leptoceratopsidae, known primarily from North America, or the Asian Protoceratopsidae are more closely related to the Ceratopsoidea is disputed. In contrast to the point of view presented here, a number of studies assume that the Protoceratopsidae are the sister group of the Ceratopsoidea.

The Ceratopsidae were found almost exclusively in western North America, finds are known from today's Alaska to Mexico . Since a closest relative, Zuniceratops , also lived there, the group may have developed on this continent as well. The only known exception is the Sinoceratops , which was only described in 2010 and found in what is now China .

The Ceratopsidae are only known from the Upper Cretaceous for a relatively short geological period, from the Campanian to the Maastrichtian , and are therefore around 83 to 66 million years old.

Internal system

The Ceratopsidae can be divided into two subfamilies, the Centrosaurinae and the Chasmosaurinae . The Centrosaurinae usually had a longer nasal horn, shorter or missing over-eye horns and a shorter neck-shield. In the Chasmosaurinae, the nasal horn was mostly short, the over-eye horns and the neck shield, however, elongated. (For details see under Features .)

The generic list below follows P. Dodson et al. (2004), but includes genera described since then.

Several studies came to the conclusion that both the Ceratopsidae and the two subfamilies are very likely monophyletic . The greatest uncertainty arose in the position of Einiosaurus within the Centrosaurinae, which is either the sister group of all other Centrosaurinae, the Achelousaurus - Pachyrhinosaurus clade or the Styracosaurus - Centrosaurus clade. The other lineages are stable and are shown in the following cladogram.

 Ceratopsidae  
  Centrosaurinae  
  NN  

 Achelousaurus


   

 Pachyrhinosaurus



  NN  

 Styracosaurus


   

 Centrosaurus



   

 Einiosaurus (position unclear)


Template: Klade / Maintenance / 3

  Chasmosaurinae  
  NN  

 Chasmosaurus


   

 Pentaceratops



  NN  
  NN  

 Arrhinoceratops


   

 Anchiceratops



  NN  
  NN  

 Diceratus


   

 Torosaurus



   

 Triceratops






The Albertaceratops , first described in 2007 , is classified by its researchers within the Centrosaurinae as a sister taxon of the other representatives of this group.

Ceratopsidae and humans

History of discovery and research

Othniel Charles Marsh coined the term Ceratopsidae and described well-known genera such as Triceratops

The first known Ceratopsidae were Agathaumas in 1872 , Polyonax in 1874 and Dysganus in 1876 , all described by Cope . The rudimentary finds initially did not allow any conclusions to be drawn about the animals, which is also evident from the fact that Marsh named a find bison alticornis in 1887, i.e. thought it was a long-horned bison . It was only with the discovery of Triceratops in 1889 and Torosaurus in 1891 (both also described by Marsh) that the actual appearance of the Ceratopsidae could be guessed for the first time. The name Ceratopsidae was coined by Marsh in 1890, after which it was named Ceratops , a poorly preserved find from 1888. Although the forms “Ceratopia” and “Ceratopidae” (each without s) would be grammatically correct, many frameworks still use the incorrect ones, coined by Marsh Designations.

At the beginning of the 20th century, other representatives of this group were discovered with Centrosaurus and Diceratus , and in 1904 the first assembled skeleton was erected in the National Museum of Natural History in Washington . In 1907, " The Ceratopsia " was the first comprehensive monograph on these animals, written by Lull based on the studies of Marsh and Hatcher , who had recently died . In the 1910s and 1920s, Canada was the site of numerous genera such as Anchiceratops , Chasmosaurus and Styracosaurus . In 1933 Lull wrote his revised studies in which he distinguished a group with a short neck shield and a group with a long neck shield. Except for the fact that Triceratops belonged to the long-shielded Chasmosaurinae despite having a short neck shield, this classification already corresponded to the subfamilies recognized today.

After the Second World War, Pachyrhinosaurus (1950) was initially only discovered as a single new genus; paleobiological and ecological studies increasingly came to the fore. More than 30 years after Pachyrhinosaurus , Avaceratops, the next representative of the Ceratopsidae, was described in 1986 . In the 1990s, Achelousaurus and Einiosaurus emerged . Since then, the systematics of this family has also been investigated using cladistic methods, among others by Thomas Lehman and Peter Dodson.

New genera were also described in the 21st century, Agujaceratops , Albertaceratops and Eotriceratops in 2006 and 2007. The unanswered questions suggest that intensive future research can be expected.

In popular culture

Some representatives of the Ceratopsidae, especially Triceratops , are among the most famous dinosaurs and have a fixed place in popular works on dinosaurs. Triceratops and Agathaumas could already be seen in the 1925 film The Lost World . They appear in Jurassic Park as well as in the cartoon In a Land Before Time . Even documentaries dealing with these animals, such as dinosaurs - In the Realm of the Giants (Walking with Dinosaurs) or fight the dinosaur (The Truth About Killer Dinosaurs), where the battle between Triceratops and Tyrannosaurus is discussed.

literature

Individual evidence

  1. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , pp. 257-272, online ( memento of the original from July 13, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / press.princeton.edu
  2. ↑ a b c Xing Xu , KeBai Wang, XiJin Zhao , DunJing Li: First ceratopsid dinosaur from China and its biogeographical implications. In: Chinese Science Bulletin. Vol. 55, No. 16, 2010, ISSN  1001-6538 , pp. 1631-1635, doi : 10.1007 / s11434-009-3614-5 .
  3. ↑ Dodson et al. (2004), p. 494.
  4. ↑ a b c d Dodson et al. (2004).
  5. ↑ Donald B. Brinkman, Michael J. Ryan, David A. Eberth: The paleogeographic and stratigraphic distribution of ceratopsids (Ornithischia) in the Upper Judith River Group of Western Canada. In: Palaios. Vol. 13, No. 2, 1998, ISSN  0883-1351 , pp. 160-169, doi : 10.1043 / 0883-1351 (1998) 013 <0160: TPASDO> 2.0.CO; 2 .
  6. ↑ Fastovsky & Weishampel (2005), p. 171.
  7. ^ PE Wheeler: Elaborate CNS cooling structures in large dinosaurs. In: Nature . Vol. 275, No. 5679, 1978, pp. 441-443, doi : 10.1038 / 275441a0 .
  8. ↑ Лео Шйович Давиташвили: Теория полового отбора. Изд-во Академии наук СССР, Москва 1961.
  9. ↑ Fastovsky & Weishampel (2005), pp. 174-175.
  10. ^ Andrew A. Farke, Ewan DS Wolff, Darren H. Tanke: Evidence of Combat in Triceratops. In: PLoS ONE . Vol. 4, No. 1, 2009, e4252, doi : 10.1371 / journal.pone.0004252 .
  11. ^ Section Horns and Frills. In: Dodson et al. (2004), p. 512.
  12. ^ Robert T. Bakker : The Return of the Dancing Dinosaurs. In: Sylvia J. Czerkas, Everett C. Olson (Eds.): Dinosaurs Past and Present. Volume 1. Natural History Museum of Los Angeles County, Los Angeles CA 1987, ISBN 0-938644-24-6 , pp. 38-69.
  13. ^ Rolf E. Johnson, John H. Ostrom : The forelimb of Torosaurus and an analysis of the posture and gait of ceratopsian dinosaurs. In: Jeff Thomason (Ed.): Functional Morphology in Vertebrate Paleontology. Cambridge University Press, Cambridge et al. 1995, ISBN 0-521-44095-5 , pp. 205-218; or Peter Dodson, James O. Farlow: The forelimb carriage of ceratopsid dinosaurs. In: Donald L. Wolberg, Edmund Stump, Gary Rosenberg (Eds.): Dinofest International. Proceedings of a symposium held at Arizona State University. Academy of Natural Sciences, Philadelphia PA 1997, ISBN 0-935868-94-1 , pp. 393-398.
  14. ^ A b Gregory S. Paul, Per Christiansen: Forelimb Posture in Neoceratopsian Dinosaurs: Implications for Gait and Locomotion. In: Paleobiology. Vol. 26, No. 3, 2000, ISSN  0094-8373 , pp. 450-465, doi : 10.1666 / 0094-8373 (2000) 026 <0450: FPINDI> 2.0.CO; 2 .
  15. ^ Richard A. Thulborn: Speeds and gaits of dinosaurs . In: Palaeogeography, Palaeoclimatology, Palaeoecology. Vol. 38, No. 3/4, 1982, ISSN  0031-0182 , pp. 227-256, doi : 10.1016 / 0031-0182 (82) 90005-0 .
  16. ↑ a b Section Feeding, Diet and Respiration. In: Dodson et al. (2004), pp. 511-512.
  17. Jump up ↑ MJ Coe, David L. Dilcher, James O. Farlow, David M. Jarzen, Dale A. Russell : Dinosaurs and Land Plants. In: Else Marie Friis, William Gilbert Chaloner, Peter R. Crane (Eds.): The Origins of Angiosperms and their Biological Consequences. Cambridge University Press, Cambridge et al. 1987, ISBN 0-521-32357-6 , pp. 225-259.
  18. ↑ Scott D. Sampson, Michael Ryan, Darren H. Tanke: Craniofacial ontogeny in centrosaurine dinosaurs (Ornithischia: Ceratopsidae): Taxonomic and behavioral implications. In: Zoological Journal of the Linnean Society. Vol. 121, No. 3, 1997, ISSN  0024-4082 , pp. 293-337, doi : 10.1111 / j.1096-3642.1997.tb00340.x .
  19. ↑ after Xing Xu , Catherine A. Forster, James M. Clark , Jinyou Mo: A basal ceratopsian with transitional features from the Late Jurassic of northwestern China. In: Proceedings of the Royal Society. Series B: Biological Sciences. Vol. 273, No. 1598, 2006, ISSN  0950-1193 , pp. 2135-2140, doi : 10.1098 / rspb.2006.3566 , digital copy (PDF; 916.04 kB) ; and Dodson et al., (2004).
  20. ↑ about Peter J. Makovicky : A Montanoceratops cerorhynchus (Dinosauria: Ceratopsia) braincase from the Horseshoe Canyon Formation of Alberta. In: Darren H. Tanke, Kenneth Carpenter (Eds.): Mesozoic Vertebrate Life. Indiana University Press et al., Bloomington IN et al. 2001, ISBN 0-253-33907-3 , pp. 243-262; or Brenda Chinnery: Description of Prenoceratops pieganensis gen et sp. nov. (Dinosauria: Neoceratopsia) from the Two Medicine Formation of Montana. In: Journal of Vertebrate Paleontology. Vol. 24, No. 3, 2004, ISSN  0272-4634 , pp. 572-590, doi : 10.1671 / 0272-4634 (2004) 024 [0572: DOPPGE] 2.0.CO; 2 .
  21. ↑ Scott D. Sampson, Eric K. Lund, Mark A. Loewen, Andrew A. Farke, Katherine E. Clayton: A remarkable short-snouted horned dinosaur from the Late Cretaceous (late Campanian) of southern Laramidia. In: Proceedings of the Royal Society. Series B: Biological Sciences. Vol. 280, No. 1766, 2013, ISSN  0950-1193 , pp. 1–7, doi : 10.1098 / rspb.2013.1186 .
  22. ^ Andrew T. McDonald, John R. Horner : New Material of "Styracosaurus" ovatus from the Two Medicine Formation of Montana. In: Michael J. Ryan, Brenda J. Chinnery-Allgeier, David A. Eberth (Eds.): New Perspectives on Horned Dinosaurs. The Royal Tyrrell Museum Ceratopsian Symposium. Indiana University Press, Bloomington IN et al. 2010, ISBN 978-0-253-35358-0 , pp. 156-168.
  23. ↑ Andrew A. Farke, Michael J. Ryan, Paul M. Barrett , Darren H. Tanke, Dennis R. Braman, Mark A. Loewen, Mark R. Graham: A new centrosaurine from the Late Cretaceous of Alberta, Canada, and the evolution of parietal ornamentation in horned dinosaurs. In: Acta Palaeontologica Polonica. Vol. 56, No. 4, 2011, ISSN  0567-7920 , pp. 691-702, doi : 10.4202 / app.2010.0121 .
  24. ↑ David C. Evans, Michael J. Ryan. Cranial Anatomy of Wendiceratops pinhornensis gen. Et sp. nov., a Centrosaurine Ceratopsid (Dinosauria: Ornithischia) from the Oldman Formation (Campanian), Alberta, Canada, and the Evolution of Ceratopsid Nasal Ornamentation. PLOS ONE, 2015; 10 (7): e0130007 DOI: 10.1371 / journal.pone.0130007
  25. ↑ a b Scott D. Sampson, Mark A. Loewen, Andrew A. Farke, Eric M. Roberts, Catherine A. Forster, Joshua A. Smith, Alan L. Titus: New Horned Dinosaurs from Utah Provide Evidence for intra Continental Dinosaur endemism. In: PLoS ONE. Vol. 5, No. 9, 2010, e12292, doi : 10.1371 / journal.pone.0012292 .
  26. ↑ Michael J. Ryan, David C. Evans, Philip J. Currie , Mark A. Loewen: A new chasmosaurine from northern Laramidia expands frill disparity in ceratopsid dinosaurs. In: Natural Sciences . Vol. 101, No. 6, 2014, pp. 505-512, doi : 10.1007 / s00114-014-1183-1 .
  27. ↑ John B. Scannella, John R. Horner : Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny. In: Journal of Vertebrate Paleontology. Vol. 30, No. 4, 2010, pp. 1157–1168, doi : 10.1080 / 02724634.2010.483632 .
  28. ^ Michael J. Ryan: A new basal centrosaurine ceratopsid from the Oldman Formation, southeastern Alberta. In: Journal of Paleontology. Vol. 81, No. 2, 2007, ISSN  0022-3360 , pp. 376-396, doi : 10.1666 / 0022-3360 (2007) 81 [376: ANBCCF] 2.0.CO; 2 .
  29. ^ John B. Hatcher : The Ceratopsia (= Monographs of the United States Geological Survey. 49, ISSN  0886-7550 ). Based on preliminary studies by Othniel C. Marsh . Edited and completed by Richard S. Lull . US Government Printing Office, Washington DC 1907.
  30. ^ Richard Swann Lull: A revision of the Ceratopsia or horned dinosaurs (= Memoirs of the Peabody Museum of Natural History. Vol. 3, Part 3, ZDB -ID 1002336-7 ). The Tuttle - Morehouse & Taylor, New Haven CT 1933, digitized .

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This article was added to the list of excellent articles on October 29, 2008 in this version .