Utahraptor
| Utahraptor | ||||||||||||
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Skeletal reconstruction of Utahraptor ostrommaysorum |
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| Temporal occurrence | ||||||||||||
| Lower Cretaceous ( Barremium ) | ||||||||||||
| 130.7 to 126.3 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Utahraptor | ||||||||||||
| Kirkland , Gaston , Burge , 1993 | ||||||||||||
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Utahraptor is a genus of carnivorous dinosaurs from the Dromaeosauridae group . Utahraptor is known only from very fragmentary remains that were discovered in eastern Utah ( USA ) andare dated tothe Lower Cretaceous ( Barremium ).
With an estimated length of 7 meters, Utahraptor is the largest known dromaeosaurid. This genus was scientifically described in 1993 by James Ian Kirkland , Robert Gaston and Donald Burge , the only species being Utahraptor ostrommaysorum . Because of its size, Utahraptor is one of the dromaeosaurids most frequently received in popular depictions.
features
The Utahraptor is estimated by Kirkland and colleagues to be about 7 meters long and 500 kg. Only Achillobator from the Upper Cretaceous Mongolia reached a similar size among the dromaeosaurids , which is estimated to be almost 5 meters long. The most common claws are fossilized. Like other dromaeosaurids, the Utahraptor exhibited an enlarged sickle claw on the inner toe. This is handed down through a 22 cm long fossil; reconstructed it was probably 24 cm long. Kirkland and colleagues described supposed hand claws that were large and significantly thinner than all other dromaeosaurids, which is why they would have been better suited as weapons for cutting. However, it later turned out that these claws were actually foot claws.
The intermaxillary bone (premaxillary) of the skull is known. Kirkland and colleagues described a lacrimal bone , but this later turned out to be the postorbital of the nodosaur Gastonia . The paired intermaxillary bone, a tooth-bearing bone that lies in front of the upper jaw (maxilla), has four teeth on each side, as in other dromaeosaurids. Only two teeth are largely preserved: the first tooth is 31 mm long, the second 45 mm long. In most of the other dromaeosaurids, the denticles (teeth) on the front incisal edge of the teeth are significantly smaller and more numerous than on the rear; in the case of Utahraptor , however, this difference is only slight. Unlike other dromaeosaurids, the denticles are simple and blunt; Similar denticles are found only in Dromaeosaurus . The denticles of Dromaeosaurus are proportionally larger. There are three known tail vertebrae. The vertebral bodies were platycoel, that is, flat on one end and convex on the other. The vertebrae show that the tail, like most other dromaeosaurids, was reinforced by rod-like vertebral processes (elongated post- and prezygapophyses and chevron bones ). The shin is straight and massive, which indicates a strong leg. Kirkland and colleagues speculate that this adaptation served to use the sickle claw as powerfully as possible.
Systematics
Today Utahraptor is considered to be closely related to Achillobator and Dromaeosaurus , together these genera form a separate group within the Dromaeosauridae, the Dromaeosaurinae. Kirkland and colleagues already suspected on the basis of the similarities in the shape of the denticles that Utahraptor is more likely to be attributed to the Dromaeosaurinae than to the Velociraptorinae.
Function of the hands and feet and speed
Kirkland and colleagues speculated that if Utahraptor lived in packs, it could hunt down very large prey, such as sauropods up to 20 meters long. They followed the common view at the time that dromaeosaurids had jumped on large prey, held on with their long arms and slashed the prey's belly with their sickle claws. They speculated that, thanks to its sheer size , Utahraptor could have stabbed prey with its sickle claw without running the risk of losing its balance as a result of the force of this attack. In contrast to smaller dromaeosaurids, he could have used his hand claws not only to hold on, but also to wound the prey. This would be indicated by the thinner hand claws, which were better adapted to cutting than the claws of other dromaeosaurids. With Utahraptor, the hand claws could have played an almost as important role in killing the prey as the sickle claw. However, it later became apparent that the supposed hand claws were actually foot claws.
Recent studies by Manning and colleagues (2005) using a mechanical robotic model of the Deinonychus foot have shown that the sickle claw of the dromaeosaurids cannot be used for slitting. Instead, it was ideal for clinging to prey. Injuries, according to these researchers, were primarily caused by the claws and teeth. The sickle claw could also have been used to puncture the carotid artery and windpipe, as suggested by the famous fossil of a fighting Velociraptor .
Comparisons with Deinonychus suggest that the tibia was proportionally shorter than this one, and that the femur and tibia were about the same length. This corresponds to the proportions found in other larger theropods. The researchers conclude that Utahraptor could not run proportionally as fast as Deinonychus or Velociraptor . Utahraptor was at least as fast as the Iguanodontids , which could have been among its prey.
Finds, history of discovery and naming
The fossils come from two quarries located approximately 25 miles apart in eastern Utah near Arches National Park. The sedimentary rocks from which the fossils originate belong stratigraphically to the Cedar Mountain Formation , an important fossil deposit of the Lower Cretaceous.
The first Utahraptor fossils were excavated in the summer of 1975 by Jim Jensen and his group in the Dalton Well Quarry and have since been kept in the Brigham Young Earth Science Museum in Provo, Utah. The Dalton Well Quarry contained hundreds of relatively well-preserved bones. Since the bones were transported before they were embedded, it is a hodgepodge of individual bones from different individuals. The bones that were later ascribed to Utahraptor are two foot claws (BYU 13068 and BYU 9438, originally identified as hand claws), a middle caudal vertebra (BYU 9435), and two rear (distal) caudal vertebrae (BYU 9435 and 9436) .
Additional Utahraptor bones were discovered in the Gaston Quarry in October 1991 during the excavation of a nodosaur skeleton. A total of over 300 bones were discovered in this quarry in the summers of 1991 and 1992. These excavations were led by Kirkland and Burge and were part of a joint project between the Dinamation International Society and the College of Eastern Utah Prehistoric Museum . The fossils are kept in the latter. The age of the sediments from this site was dated radiometrically to 126 million years (Upper Barremian, Lower Cretaceous). Utahraptor fossils from this site include the holotype specimen (specimen number CEU 184v.86), which is the sickle claw of the right foot. In addition, a claw (CEU 184v.294), a shin (tibia, CEU 184v.260), a tear bone (lacrimale, CEU 184v.83) and an intermaxillary bone (premaxillary, CEU 184v.400) were found.
In 1993 the new species and genus was scientifically described by Kirkland, Gaston and Burge. The name Utahraptor is made up of the place where it was found, the US state of Utah, and raptor , which comes from Latin and means "predator". The species name ostrommaysorum honors John Ostrom and Chris Mays. John Ostrom was an eminent palaeontologist who made a special contribution to the study of Deinonychus . Chris Mays is the founder of the Dinamation International Society, which initiated the research and helped fund it. The original plan was to name the species Utahraptor spielbergi in honor of Steven Spielberg , the director of the highly successful dinosaur adventure film Jurassic Park . Spielberg's lawyers objected, however. In the first description the species is called Utahraptor ostrommaysi . However, the International Rules for Zoological Nomenclature (ICZN) mandate that the correct Latin genitive plural ending -orum must be used, as ostrommaysi refers to more than one person.
In popular culture
Utahraptor appears in a variety of popular depictions about dinosaurs. The novel Raptor Red (1995) by paleontologist Robert Bakker is written from the perspective of a female Utahraptor . Utahraptor appears in the BBC documentary film Dinosaurier - Im Reich der Gianten ( Walking with Dinosaurs ). Another example is the novella Raptor by Paul Zindel . In most of these depictions, Utahraptor appears without feathers. In fact, feathers have never been found associated with Utahraptor fossils. Nevertheless, the evidence of feathers in a large number of other dromaeosaurids suggests that all members of the group, including the Utahraptor, were feathered (principle of phylogenetic clasp).
supporting documents
literature
- James Ian Kirkland , Donald Burge, Robert Gaston: A large dromaeosaur [Theropoda] from the Lower Cretaceous of eastern Utah. In: Hunteria. Vol. 2, No. 10, 1993, ZDB -ID 1251702-1 , pp. 1-16, digitized version (PDF, 5.77 MB) .
Individual evidence
- ^ A b Alan H. Turner, Diego Pol, Julia A. Clarke, Gregory M. Erickson, Mark A. Norell : A Basal Dromaeosaurid and Size Evolution Preceding Avian Flight. In: Science . Vol. 317, No. 5843, 2007, pp. 1378-1381, doi : 10.1126 / science.1144066 , digitized version (PDF; 507.41 KB) , Supporting Online Material (PDF; 755.11 KB) .
- ↑ a b c Phil Senter: A method for distinguishing dromaeosaurid manual unguals from pedal “sickle claws” In: Bulletin of Gunma Museum of Natural History. Vol. 11, 2005, ISSN 1342-4092 , pp. 1–6, (PDF; 201.22 KB) ( Memento of the original dated August 8, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. .
- ↑ a b Micky Mortimer: Utahraptor ostrommaysorum. In: The Theropod Database Blog. Retrieved June 18, 2010 .
- ↑ Nicholas R. Longrich, Philip J. Currie : A microraptorine (Dinosauria – Dromaeosauridae) from the Late Cretaceous of North America. In: Proceedings of the National Academy of Sciences of the United States of America . Vol. 106, No. 13, 2009, pp. 5002-5007, doi : 10.1073 / pnas.0811664106 .
- ^ Phillip L. Manning, David Payne, John Pennicott, Paul M. Barrett , Roland A. Ennos: Dinosaur killer claws or climbing crampons? In: Biology Letters. Vol. 2, No. 1, 2005, ISSN 1744-9561 , pp. 110-112, doi : 10.1098 / rsbl.2005.0395 .
- ↑ Ken Carpenter : Evidence of predatory behavior by theropod dinosaurs. In: Gaia. Revista de Geociências. Vol. 15, 1998, ISSN 0871-5424 , pp. 135-144.
- ↑ James I. Kirkland, Scott K. Madsen: The Lower Cretaceous Cedar Mountain Formation, eastern Utah: the view up an always interesting learning curve. In: William R. Lund (Ed.): Field Guide to Geologic Excursions in Southern Utah (= Utah Geological Association. Publication. Vol. 35, ISSN 0375-8176 ). Geological Society of America Rocky Mountain Section, 2007 Annual Meeting, Dixie State College, St. George, Utah, May 7-9, 2007. Utah Geological Association, Salt Lake City UT 2007, pp. 1-108.
- ^ Donald F. Glut : Dinosaurs. The Encyclopedia. McFarland & Co, Jefferson NC et al. 1997, ISBN 0-89950-917-7 .
- ↑ Xing Xu , Zhonghe Zhou , Xiaolin Wang, Xuewen Kuang, Fucheng Zhang, Xiangke Du: Four-winged dinosaurs from China. In: Nature . Vol. 421, No. 6921, 2003, pp. 335-340, doi : 10.1038 / nature01342 .
