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Fused and Vaulted Nasals of Tyrannosaurid Dinosaurs: Implications for Cranial Strength and Feeding Mechanics
Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics ERIC SNIVELY, DONALD M. HENDERSON, and DOUG S. PHILLIPS Snively, E., Henderson, D.M., and Phillips, D.S. 2006. Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics. Acta Palaeontologica Polonica 51 (3): 435–454. Tyrannosaurid theropods display several unusual adaptations of the skulls and teeth. Their nasals are fused and vaulted, suggesting that these elements braced the cranium against high feeding forces. Exceptionally high strengths of maxillary teeth in Tyrannosaurus rex indicate that it could exert relatively greater feeding forces than other tyrannosaurids. Areas and second moments of area of the nasals, calculated from CT cross−sections, show higher nasal strengths for large tyrannosaurids than for Allosaurus fragilis. Cross−sectional geometry of theropod crania reveals high second moments of area in tyrannosaurids, with resulting high strengths in bending and torsion, when compared with the crania of similarly sized theropods. In tyrannosaurids trends of strength increase are positively allomeric and have similar allometric expo− nents, indicating correlated progression towards unusually high strengths of the feeding apparatus. Fused, arched nasals and broad crania of tyrannosaurids are consistent with deep bites that impacted bone and powerful lateral movements of the head for dismembering prey. Key words: Theropoda, Carnosauria, Tyrannosauridae, biomechanics, feeding mechanics, computer modeling, com− puted tomography. Eric Snively [[email protected]], Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada; Donald M. Henderson [[email protected]], Royal Tyrrell Museum of Palaeontology, Box 7500, Drumheller, Alberta T0J 0Y0, Canada; Doug S. -
PALEONTOLOGY and BIOSTRATIGRAPHY of MONGOLIA the JOINT SOVIET-MONGOLIAN PALEONTOLOGICAL EXPEDITION (Transactions, Vol
PALEONTOLOGY AND BIOSTRATIGRAPHY OF MONGOLIA THE JOINT SOVIET-MONGOLIAN PALEONTOLOGICAL EXPEDITION (Transactions, vol. 3) EDITORIAL BOARD: N. N. Kramarenko (editor-in-chief) B. Luvsandansan, Yu. I. Voronin, R. Barsbold, A. K. Rozhdestvensky, B. A. Trofimov, V. Yu. Reshetov 1976 S. M. Kurzanov A NEW CARNOSAUR FROM THE LATE CRETACEOUS OF NOGON-TSAV, MONGOLIA* The Upper Cretaceous locality of Nogon-Tsav, located in the Zaltaika Gobi, 20 km NW of Mt. Ongon-Ulan-Ula, was discovered by geologists of the MNR. Then, in a series of years (1969–1971, 1973) the joint Soviet-Mongolian Geological Expedition investigated the site. According to the oral report of B. Yu. Reshetova, the deposits in this region are composed basically of sandstone and clay, clearly subdivided into two deposits. The lower great thickness contains many complete skulls, separate bones of tarbosaurs, ornithomimids, and claws of therizinosaurs. The upper red-colored beds are characterized only by scattered fragments of skulls. The fragments described below are of a new carnivorous dinosaur, Alioramus remotus (coll. South Goby region), from the family Tyrannosauridae, which occurs in the lower gray beds. Genus Alioramus Kurzanov, gen. nov. G e n u s n a m e from alius (Lat.) – other, ramus (Lat.) – branch; masc. G e n o t y p e — A. remotus Kurzanov, sp. nov., Upper Cretaceous, Nemegetinskaya suite, southern Mongolia. D i a g n o s i s . Tyrannosaurid of average size. Skull low, with highly elongated jaws. Nasals with well-developed separate crests of 1–l.5 cm height. Second antorbital fenestrae displaced forward, reaching the anterior end of the 5th tooth. -
A. K. Rozhdestvensky HISTORY of the DINOSAUR FAUNA of ASIA
A. K. Rozhdestvensky HISTORY OF THE DINOSAUR FAUNA OF ASIA AND OTHER CONTINENTS AND QUESTIONS CONCERNING PALEOGEOGRAPHY* The distribution and evolution of dinosaur faunas during the period of their existence, from the Late Triassic to the end of the Cretaceous, shows a close connection with the paleogeography of the Mesozoic. However these questions were hard to examine on a global scale until recently, because only the dinosaurs of North America were well known, where during the last century were found their richest deposits and where the best paleontologists were studying them — J. Leidy, E. Cope, O. Marsh, R. Lull, H. Osborn, C. Gilmore, B. Brown, and later many others. On the remaining continents, including Europe, where the study of dinosaurs started earlier than it did in America, the information was rather incomplete due to the fragmentary condition of the finds and rare, episodic studies. The Asian continent remained unexplored the longest, preventing any intercontinental comparisons. Systematic exploration and large excavations of dinosaur locations in Asia, which began in the last fifty years (Osborn, 1930; Efremov, 1954; Rozhdestvenskiy, 1957a, 1961, 1969, 1971; Rozhdestvenskiy & Chzhou, 1960; Kielan-Jaworowska & Dovchin, 1968; Kurochkin, Kalandadze, & Reshetov, 1970; Barsbold, Voronin, & Zhegallo, 1971) showed that this continent has abundant dinosaur remains, particularly in its central part (Fig. 1). Their study makes it possible to establish a faunal connection between Asia and other continents, correlate the stratigraphy of continental deposits of the Mesozoic, because dinosaurs are reliable leading forms, as well as to make corrections in the existing paleogeographic structure. The latter, in their turn, promote a better understanding of the possible paths of distribution of the individual groups of dinosaurs, the reasons for their appearance, their development, and disappearance. -
Skulls of Tarbosaurus Bataar and Tyrannosaurus Rex Compared
Giant theropod dinosaurs from Asia and North America: Skulls of Tarbosaurus bataar and Tyrannosaurus rex compared Jørn H. Hurum and Karol Sabath Acta Palaeontologica Polonica 48 (2), 2003: 161-190 The skull of a newly prepared Tarbosaurus bataar is described bone by bone and compared with a disarticulated skull of Tyrannosaurus rex. Both Tarbosaurus bataar and Tyrannosaurus rex skulls are deep in lateral view. In dorsal view, the skull of T. rex is extremely broad posteriorly but narrows towards the snout; in Ta. bataar the skull is narrower (especially in its ventral part: the premaxilla, maxilla, jugal, and the quadrate complex), and the expansion of the posterior half of the skull is less abrupt. The slender snout of Ta. bataar is reminiscent of more primitive North American tyrannosaurids. The most obvious difference between T. rex and Ta. bataar is the doming of the nasal in Ta. bataar which is high between the lacrimals and is less attached to the other bones of the skull, than in most tyrannosaurids. This is because of a shift in the handling of the crushing bite in Ta. bataar . We propose a paleogeographically based division of the Tyrannosaurinae into the Asiatic forms (Tarbosaurus and possibly Alioramus) and North American forms (Daspletosaurus and Tyrannosaurus). The division is supported by differences in anatomy of the two groups: in Asiatic forms the nasal is excluded from the major series of bones participating in deflecting the impact in the upper jaw and the dentary-angular interlocking makes a more rigid lower jaw. Key words: Dinosauria, Theropoda, Tyrannosauridae, Tarbosaurus, Tyrannosaurus, skull, anatomy, Mongolia. -
Immigrant Species, Or Native Species?
The Journal of Paleontological Sciences: JPS.C.2017.01 TESTING THE HYPOTHESES OF THE ORIGIN OF TYRANNOSAURUS REX: IMMIGRANT SPECIES, OR NATIVE SPECIES? __________________________________________________________________________________________________________________ Chan-gyu Yun Vertebrate Paleontological Institute of Incheon, Incheon 21974, Republic of Korea & Biological Sciences, Inha University, Incheon 22212, Republic of Korea [email protected] __________________________________________________________________________________________________________________ Abstract: It is an undoubtable fact that Tyrannosaurus rex is the most iconic dinosaur species of all time. However, it is currently debatable whether this species has a North American origin or Asian origin. In this paper, I test these two hypotheses based on current fossil records and former phylogenetic analyses. Phylogenetic and fossil evidence, such as derived tyrannosaurine fossils of Asia, suggests that the hypothesis of an Asian origin of Tyrannosaurus rex is the most plausible one, but this is yet to be certain due to the scarcity of fossil records. INTRODUCTION The most famous and iconic dinosaur of all time, Tyrannosaurus rex, is only known from upper Maastrichtian geological formations in Western North America (e.g. Carr and Williamson, 2004; Larson, 2008). However, older relatives of Tyrannosaurus rex (e.g. Daspletosaurus, Tarbosaurus) are known from both Asia and North America. This leads to an evolutionary question: is the origin of Tyrannosaurus rex from Asia, or North America? About six of the currently valid tyrannosaurine taxa were described in the twenty-first century (based on parsimony analysis of Brusatte and Carr, 2016), with new species which are being described (Sebastian Dalman, Pers. Comm., 2016; Thomas Carr, Pers. Comm., 2016). It can be said that "now" is the "golden age” for studying tyrannosaurine evolution. -
Limb Design, Function and Running Performance in Ostrich-Mimics and Tyrannosaurs
GAIA Nº 15, LISBOA/LISBON, DEZEMBRO/DECEMBER 1998, pp. 257-270 (ISSN: 0871-5424) LIMB DESIGN, FUNCTION AND RUNNING PERFORMANCE IN OSTRICH-MIMICS AND TYRANNOSAURS Gregory S. PAUL 3109 N Calvert St. Side Apt., BALTIMORE MD 21218. USA ABSTRACT: Examination of the limb morphology of small ornithomimids and large tyranno- saurids shows that they remained remarkably constant in design regardless of size. The changes that were present were consistent with maintaining limb strength and function constant with size. It is concluded that ornithomimid and tyrannosaurid legs functioned in a similar manner, and always exhibit the features normally associated with a fast running gait. This is in contrast to modern animals, in which elephants as gigantic as large tyranno- saurids have limbs that are modified for a slow walking gait. INTRODUCTION to run observed in elephants. The hypothesis can be challenged if it can be shown that at least some ex- Because they had long, gracile, bird-like legs, it tinct giants retained the skeletal adaptations for run- has long been accepted that the smaller predatory ning observed in smaller species, and in their own dinosaurs were swift runners (O [& GREG- SBORN offspring. In turn, the hypothesis that giants can run ], 1916; COLBERT, 1961; RUSSELL, 1972; ORY fast if they retain limbs similar to smaller runners can C , 1978; THULBORN, 1982; PAUL, 1988; OOMBS be challenged if it is shown that the skeleton is too H , 1994). Much more controversial has been OLTZ vulnerable to structural failure. the locomotory abilities of their giant relatives, which have been restored as no faster than elephants BODY MASSES (LAMBE, 1917; HALSTEAD &HALSTEAD, 1981; THUL- BORN, 1982; BARSBOLD, 1983), able to run at only Sources for mass data for extinct and extant ani- modest speeds (COOMBS, 1978; MOLNAR &FAR- mals include PAUL (1988, 1997), NOWAK (1991) and LOW, 1990; HORNER &LESSEM, 1993; FARLOW, MATTHEWS (1994). -
Cranial Anatomy of Allosaurus Jimmadseni, a New Species from the Lower Part of the Morrison Formation (Upper Jurassic) of Western North America
Cranial anatomy of Allosaurus jimmadseni, a new species from the lower part of the Morrison Formation (Upper Jurassic) of Western North America Daniel J. Chure1,2,* and Mark A. Loewen3,4,* 1 Dinosaur National Monument (retired), Jensen, UT, USA 2 Independent Researcher, Jensen, UT, USA 3 Natural History Museum of Utah, University of Utah, Salt Lake City, UT, USA 4 Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, USA * These authors contributed equally to this work. ABSTRACT Allosaurus is one of the best known theropod dinosaurs from the Jurassic and a crucial taxon in phylogenetic analyses. On the basis of an in-depth, firsthand study of the bulk of Allosaurus specimens housed in North American institutions, we describe here a new theropod dinosaur from the Upper Jurassic Morrison Formation of Western North America, Allosaurus jimmadseni sp. nov., based upon a remarkably complete articulated skeleton and skull and a second specimen with an articulated skull and associated skeleton. The present study also assigns several other specimens to this new species, Allosaurus jimmadseni, which is characterized by a number of autapomorphies present on the dermal skull roof and additional characters present in the postcrania. In particular, whereas the ventral margin of the jugal of Allosaurus fragilis has pronounced sigmoidal convexity, the ventral margin is virtually straight in Allosaurus jimmadseni. The paired nasals of Allosaurus jimmadseni possess bilateral, blade-like crests along the lateral margin, forming a pronounced nasolacrimal crest that is absent in Allosaurus fragilis. Submitted 20 July 2018 Accepted 31 August 2019 Subjects Paleontology, Taxonomy Published 24 January 2020 Keywords Allosaurus, Allosaurus jimmadseni, Dinosaur, Theropod, Morrison Formation, Jurassic, Corresponding author Cranial anatomy Mark A. -
New Tyrannosaur from the Mid-Cretaceous of Uzbekistan Clarifies Evolution of Giant Body Sizes and Advanced Senses in Tyrant Dinosaurs
New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs Stephen L. Brusattea,1, Alexander Averianovb,c, Hans-Dieter Suesd, Amy Muira, and Ian B. Butlera aSchool of GeoSciences, University of Edinburgh, Edinburgh EH9 3FE, United Kingdom; bZoological Institute, Russian Academy of Sciences, St. Petersburg 199034, Russia; cDepartment of Sedimentary Geology, Saint Petersburg State University, St. Petersburg 199178, Russia; and dDepartment of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560 Edited by Neil H. Shubin, The University of Chicago, Chicago, IL, and approved January 29, 2016 (received for review January 5, 2016) Tyrannosaurids—the familiar group of carnivorous dinosaurs in- We here report the first diagnostic tyrannosauroid from the mid- cluding Tyrannosaurus and Albertosaurus—were the apex predators Cretaceous, a new species from the Turonian (ca. 90–92 million in continental ecosystems in Asia and North America during the years ago) Bissekty Formation of Uzbekistan. This formation has latest Cretaceous (ca. 80–66 million years ago). Their colossal sizes recently emerged as one of the most important records of mid- and keen senses are considered key to their evolutionary and eco- Cretaceous dinosaurs globally (9–11). Possible tyrannosauroid logical success, but little is known about how these features devel- specimens from the Bissekty Formation were reported more than oped as tyrannosaurids evolved from smaller basal tyrannosauroids a half century ago (12), and, more recently, several isolated fossils that first appeared in the fossil record in the Middle Jurassic (ca. 170 were assigned to the group (9, 13), but none of these has been million years ago). -
The Expanding Earth: Indisputable Evidences of the Gobi Desert
Open Journal of Geology, 2020, 10, 1-12 https://www.scirp.org/journal/ojg ISSN Online: 2161-7589 ISSN Print: 2161-7570 The Expanding Earth: Indisputable Evidences of the Gobi Desert Alexey Ju. Retejum Lomonosov Moscow State University, Moscow, Russia How to cite this paper: Retejum, A.Ju. Abstract (2020) The Expanding Earth: Indisputable Evidences of the Gobi Desert. Open Journal The most striking contrasts that are found on the continents in paleogeographic of Geology, 10, 1-12. reconstructions of the end of the Mesozoic era are the occurrence on the place of https://doi.org/10.4236/ojg.2020.101001 the disappeared humid subtropics of the largest Gobi Desert in Eurasia with air temperatures falling below 50˚ from the freezing point and annual precipitation Received: October 28, 2019 Accepted: December 28, 2019 totals at the level of 100 mm. Science does not know the processes that can lead Published: December 31, 2019 to a cooling of the atmosphere at 70˚ and other equally radical changes in nature with a stable position of the blocks of the earth’s crust in space. Changes in the Copyright © 2020 by author(s) and environment of this magnitude can only be the result of land moving north- Scientific Research Publishing Inc. ward for a distance equal to about half the radius of the Earth. Titanosaurs, This work is licensed under the Creative Commons Attribution International described by the remains in the Gobi deposits, had a body volume, which at License (CC BY 4.0). modern gravity corresponds to a mass of 10 to 30 ton. -
Tyrannosaurs in Science
Media Inquiries: Kristin Elise Phillips, Department of Communications September 2010 212-496-3419; [email protected] www.amnh.org ________________________________________________________________________ SCIENTIFIC UNDERSTANDING OF T. REX REVISED BY A DECADE OF NEW RESEARCH AND DISCOVERY TYRANNOSAURS ARE MORE THAN LARGE CARNIVORES AT THE TOP OF THE FOOD CHAIN We’ve all heard this story: the Late Cretaceous of Asia and North America— about 65 million years ago—was dominated by several large-headed, bipedal predatory dinosaurs like Tyrannosaurus rex and Tarbosaurus that had tiny arms. But a decade of new fossil discoveries that have more than doubled the number of known tyrannosaur species has changed this tale. Older and smaller tyrannosaurs have made the evolutionary tree of this group richer and more complex. Furthermore, a series of innovative research projects on topics like bone growth and biomechanics have added an enormous amount of information about tyrannosaurs, so much so that the group could now be considered an exemplar for studying many themes in paleontology research. A new paper describing recent research and a new evolutionary tree is published in Science this week. “T. rex is the most iconic of all dinosaurs,” says Mark Norell, curator in the Division of Paleontology at the American Museum of Natural History. “Its star power has allowed a research focus into questions not normally undertaken with fossils, questions like bone growth, biomechanics, and neurology.” “We know more about tyrannosaurs than any other group of dinosaurs—even more than some groups of living organisms,” says Stephen Brusatte, a graduate student affiliated with the Museum and first author of the paper. -
Raptors in Action 1 Suggested Pre-Visit Activities
PROGRAM OVERVIEW TOPIC: Small theropods commonly known as “raptors.” THEME: Explore the adaptations that made raptors unique and successful, like claws, intelligence, vision, speed, and hollow bones. PROGRAM DESCRIPTION: Razor-sharp teeth and sickle-like claws are just a few of the characteristics that have made raptors famous. Working in groups, students will build a working model of a raptor leg and then bring it to life while competing in a relay race that simulates the hunting techniques of these carnivorous animals. AUDIENCE: Grades 3–6 CURRICULUM CONNECTIONS: Grade 3 Science: Building with a Variety of Materials Grade 3–6 Math: Patterns and Relations Grade 4 Science: Building Devices and Vehicles that Move Grade 6 Science: Evidence and Investigation PROGRAM ObJECTIVES: 1. Students will understand the adaptations that contributed to the success of small theropods. 2. Students will explore the function of the muscles used in vertebrate movement and the mechanics of how a raptor leg works. 3. Students will understand the function of the raptorial claw. 4. Students will discover connections between small theropod dinosaurs and birds. SUGGESTED PRE-VISIT ACTIVITIES UNDERstANDING CLADIstICS Animals and plants are often referred to as part of a family or group. For example, the dog is part of the canine family (along with wolves, coyotes, foxes, etc.). Scientists group living things together based on relationships to gain insight into where they came from. This helps us identify common ancestors of different organisms. This method of grouping is called “cladistics.” Cladistics is a system that uses branches like a family tree to show how organisms are related to one another. -
The Origin and Evolution of the Dinosaur Infraorder Carnosauria*
PALEONTOLOGICHESKIY ZHURNAL 1989 No. 4 KURZANOV S. M. THE ORIGIN AND EVOLUTION OF THE DINOSAUR INFRAORDER CARNOSAURIA* Paleontological Institute of the Academy of Sciences of the USSR Based on a revision of the systematic composition of the carnosaur families, a new diagram of the phylogenetic relationships within the infraorder is proposed. The question of carnosaurs cannot be considered to be resolved. Excluding the Triassic forms, carnosaurs in the broad or narrow sense have always been considered to be a group of theropods because they are only slightly different from them in fundamental features associated with large body size and a predatory lifestyle. The Late Triassic genera, such as Teratosaurus and Sinosaurus [33], were assigned to these on the basis of extremely meager material and without sufficient justification. This assignment has subsequently been rejected by most authors [13, 16, 17, 24, 25]. Huene [23] suggested that, along with the Sauropoda and Prosauropoda, the carnosaurs form a natural group Pachypodosauria, within which they are thought to be direct descendants of the prosauropods (the carnosaurs proceed directly from Teratosaurus through Magnosaurus). Studies of abundant cranial material (which actually belongs to Sellosaurus gracilis Huene) gave reason to think that the first species had been a prosauropod, whereas typical material (maxilla, ischium) belong to thecodonts from the family Poposauridae [24]. Huene’s diagram, which initially did not receive support, was widely propagated by the discovery of an unusual carnosaur Torvosaurus tanneri Galton et Jensen in the Upper Triassic deposits of Colorado [25]. The exceptionally plesiomorphic nature of some of its features, in the authors’ opinion, gave sufficient justification for removing them from the prosauropods.