Triceratops
| Triceratops | ||||||||||||
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Skeleton reconstruction of Triceratops in the Senckenberg Nature Museum in Frankfurt |
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| Temporal occurrence | ||||||||||||
| Upper Cretaceous (Upper Maastrichtian ) | ||||||||||||
| 68 to 66 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Triceratops | ||||||||||||
| Marsh , 1889 | ||||||||||||
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Triceratops horridus Marsh, 1889 |
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Triceratops (from ancient Greek τρεῖς treis 'three', κέρας kéras 'horn' and ὤψ ōps 'face'; literally therefore "three-hornedface") is a genus of bird basin dinosaurs (Ornithischia) from the group of Ceratopsia . It is one of the largest representatives of the Ceratopsidae , which were characterized by their horns and their neck shield, and one of the most famous dinosaurs at all. Triceratops lived at the end of the Upper Cretaceous in what is now North America .
features
Triceratops reached a length of up to 9 meters, its weight is estimated at 6 to 12 tons. This makes it the largest representative of the Ceratopsidae next to the but little known Eotriceratops, which was described in 2007 . A complete skeleton has not yet been found, but over 50 at least partially preserved skulls and parts of the rest of the skeleton are known.
skull
As with all Neoceratopsia, the skull of Triceratops was very large and massive. Seen from above, it had a roughly triangular shape, which was due to the pointed muzzle and the wide cheek region. 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 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. The nasal bone had a relatively small nasal horn that may have been coated with keratin .
The super-eye horns were outgrowths of the postorbital , which also formed the back edge of the eye socket and part of the cheek. These horns were relatively long, but the shape of the individual finds is very variable. The expansive cheek region was heavily modified, the Jugale formed a cheek hump.
As with all Ceratopsidae, the neck shield was formed from the parietal and scaled bones . Compared to the neck shield of related species, it was relatively short and did not have the otherwise paired openings. The outer edge of the shield was sometimes covered with undulating ossifications called epoccipitalia .
As with all Ceratopsidae, the teeth of Triceratops consisted of tooth batteries, teeth arranged in rows, which were replaced by the following tooth when they were worn out. The individual teeth were in tightly packed rows of teeth, each tooth position had three to five replacement teeth. Triceratops had 36 to 40 tooth positions. The occlusal surfaces of the dentition were almost vertical, which suggests that the teeth were mainly used for cutting.
Trunk skeleton
As in all Ceratopsidae, the first cervical vertebrae of Triceratops were fused to form the syncervical . Its limbs were robustly built, the forelegs were, as with almost all dinosaurs, shorter than the hind limbs and only reached around 70% of their length. The long bones had greatly enlarged ends with a rough surface, which could be an indication of thick cartilage balls . 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 femur was also always longer than the shin . The hind foot was short and strong and ended in four toes with blunt hooves .
Paleobiology
Social behavior and habitat
Although Triceratops one of Ceratopsidae most commonly found, but there is in contrast to many other representatives no bone beds ( "bone bed"). These are mass deposits of dozens, sometimes even thousands, of individuals. These mass deposits are an indication that some species formed associations with conspecifics for at least part of the year. Due to the lack of mass deposits of Triceratops , no statements about social behavior are possible.
Function of the horns and neck shields
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 ; in particular the “ Late Cretaceous All-Star Game ” between Tyrannosaurus and Triceratops is a popular motif in the popular representation of dinosaurs. This hypothesis, however, has some weak points: The relatives of Triceratops have each developed their own forms of horns and shields, some of which would be useless or even counterproductive, such as the regression of the super-eye horns in some species. In addition, the shield was very thin and hardly suitable as a protection against neck bites.
Today the hypothesis is rejected that the neck shield served as a starting point for a greatly enlarged masticatory muscles . Under certain circumstances the hypothesis that the shield is a tool for thermoregulation is conceivable .
The hypothesis most commonly held today is that the horns and neck shields were used for communication and discussions about territories or mating partners. One can imagine a scenario in which the display of the headdress, threatening gestures or fights between conspecifics played a role, in which it was a question of contests for territories or the mating privilege or the formation of rankings. An investigation from 2009 found many injuries in the shields of these animals, which suggests that the horns were used in fights with conspecifics.
It is quite possible that the horns and neck shields served several purposes at the same time. 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
The question of the posture and locomotion of Triceratops has turned out to be difficult to answer. Many old drawings as well as the first skeleton structures showed the animals with erect, vertical hind legs and wide apart, 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.
Anatomical studies as well as the examination of Ichnofossils (petrified footprints) came to the conclusion that these animals had their forelegs almost straight, i.e. parallel to the longitudinal plane of the body ( parasagittal ), and with only slightly angled elbows. The same investigation also came to the conclusion that these animals were able to move similar to a gallop and could reach a speed similar to that of the rhinoceros (over 40 km / h).
food
Triceratops' teeth were aligned with the perpendicular occlusal surfaces 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 that Triceratops had in common with all Ceratopsia is commonly seen as a sign of selective feeding. It should have been more suitable for grabbing and plucking, but not for biting off.
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. Exactly which plants they ate is not known; cycads , palms or ferns are conceivable .
Discovery and dating
The genus Triceratops was first described by Othniel Charles Marsh in 1889 , the type species is T. horridus . Although there have been finds of related genera (such as Agathaumas or Monoclonius ) since the 1870s , these were fragmentary and did not allow any conclusions to be drawn about the appearance of these animals. Only with Triceratops and the Torosaurus discovered at the same time did the shape of these animals become clearer. Fossil finds are known from the western USA ( Wyoming , Montana , South Dakota , North Dakota and Colorado ) and from Canada ( Alberta and Saskatchewan ).
The finds are dated in the Upper Cretaceous (late Maastrichtian ) to an age of 68 to 66 million years. Triceratops is one of the last dinosaurs. At the end of the Cretaceous Period, like all non-avian dinosaurs, it became extinct.
In a paper from 2010, John Scannella and John Horner come to the conclusion that the genera Torosaurus and Triceratops are identical, because Torosaurus individuals are only fully grown individuals of Triceratops . The genera are essentially differentiated by the different forms of the neck shield, but according to Scannella and Horner, its shape and size changes considerably in the course of the life of Triceratops . Since the two genera are only about different growth stages of the same Ceratopsiden and Triceratops is the first described genus, the name Torosaurus would only be a younger synonym of Triceratops and no longer valid ( valid ) according to the priority rule .
Systematics
External system
Triceratops is classified within the Ceratopsidae in the Chasmosaurinae , which were generally characterized by a reduced nasal horn, long over-eye horns and a long neck shield. Triceratops differs from this group with its relatively short shield and the lack of openings, which is why its membership was not recognized for a long time. According to cladistic studies, it forms a common clade with Torosaurus and Nedoceratops , the recently discovered Eotriceratops could have been an ancestor or an early representative of this clade.
Internal system
Of Triceratops skulls are completely or partially preserved known over 50, as well as numerous parts of the fuselage skeleton. Some of the finds differ from one another, but it is disputed to what extent they are different species, intraspecific variation or gender dimorphism . A total of 16 Triceratops species have been described, which are said to differ in smaller variations in the structure of the skull. Today the point of view is rather to see all the differences as intraspecific variation and to combine all the finds into a single species, Triceratops horridus .
Trivia
The main belt asteroid (9937) Triceratops was named after the genus.
The Triceratops was the mascot of the television show Neo Magazin Royale .
literature
- Peter Dodson , Catherine A. Forster, Scott D. Sampson: Ceratopsidae. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 494-513.
- David E. Fastovsky , David B. Weishampel : The Evolution and Extinction of the Dinosaurs. 2nd edition. Cambridge University Press, Cambridge et al. 2005, ISBN 0-521-81172-4 .
Web links
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , pp. 265-266, online .
- ^ Wilhelm Gemoll : Greek-German school and hand dictionary. 9th edition, reviewed and expanded by Karl Vretska ; with an introduction to the history of language by Heinz Kronasser. Freytag et al., Munich et al. 1965.
- ↑ Robert McN. Alexander: Zoological Journal of the Linnean Society. In: Mechanics of posture and gait of some large dinosaurs. Vol. 83, No. 1, 1985, ISSN 0024-4082 , pp. 1-25, doi : 10.1111 / j.1096-3642.1985.tb00871.x .
- ↑ Fastovsky & Weishampel (2005), p. 171.
- ↑ Fastovsky & Weishampel (2005), pp. 174-175.
- ^ 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 .
- ^ Section Horns and Frills. In: Dodson et al. (2004), p. 512.
- ^ 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 .
- ↑ New Analyzes Of Dinosaur Growth May Wipe Out One-Third Of Species . In: Science Daily , October 31, 2009.
- ↑ A third of the dinosaur species wrong? In: scinexx.de Das Wissensmagazin , November 4, 2009.
- ^ Montana State University: Triceratops and Torsaurus Were Same Dinosaur at Different Stages . In: ScienceDaily , July 14, 2010.
- Jump up ↑ John B. Scannell, 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, ISSN 0272-4634 , pp. 1157-1168, doi : 10.1080 / 02724634.2010.483632 .
- ↑ Dodson et al. (2004), p. 507.
- ↑ Jan Böhmermann on ZDF Neo: Waiting for the dinosaur to die , Stuttgarter Zeitung, October 31, 2013