Allosaurus Fact Sheet

Total Page：16

File Type：pdf, Size：1020Kb

Allosaurus Fact Sheet Common Name: Allosaurus fragilis Scientific Name: Fagile different lizard Wild Status: Jurassic Period, 155-150 MYA Habitat: North America, Portugal Country: Countries in North America and Portugal Shelter: Unknown Life Span: Unknown Size: 30 feet long, 8 feet tall at the hips, 1.5 tons Details Allosaurus is often referred to as “the lion of the Jurassic” and was one of the most common carnivores of its day. There is considerable debate as to whether or not Allosaurus lived in packs. It is not uncommon to find fossil deposits containing multiple individuals, and some paleontologists cite bite marks on snouts as evidence for establishing hierarchy within a social group. However, others argue that this is evidence for intraspecific competition rather than sociality. Cool Facts • Surprisingly for a large predator, Allosaurus had a relatively weak bite for its size. It most likely attacked prey by inflicting slashing-style injuries with its serrated teeth and then waiting for the animal to succumb to its wounds. • Several Allosaurus specimens bear puncture wounds indicative of being struck by the thagomizer of a Stegosaurus and there are stegosaur plates with U- shaped pieces missing that match up with an allosaur snout, providing clear evidence of a violent predator-prey relationship between the two species. Taxonomic Breakdown Kingdom: Animalia Phylum: Chordata Class: Reptilia Order: Saurischia Family: Allosauridae Genus: Allosaurus Species: A. fragilis Conservation & Helping The Allosaurus is currently extinct, and was believed to exist 155 - 150 Million Years Ago Download all our fact sheets, take our quizzes, and more, all in the Critter Squad Kids’ Zone! https://www.crittersquad.com/kids-zone/.

Copy Link

Recommended publications

Los Restos Directos De Dinosaurios Terópodos (Excluyendo Aves) En España
Canudo, J. I. y Ruiz-Omeñaca, J. I. 2003. Ciencias de la Tierra. Dinosaurios y otros reptiles mesozoicos de España, 26, 347-373. LOS RESTOS DIRECTOS DE DINOSAURIOS TERÓPODOS (EXCLUYENDO AVES) EN ESPAÑA CANUDO1, J. I. y RUIZ-OMEÑACA1,2 J. I. 1 Departamento de Ciencias de la Tierra (Área de Paleontología) y Museo Paleontológico. Universidad de Zaragoza. 50009 Zaragoza. [email protected] 2 Paleoymás, S. L. L. Nuestra Señora del Salz, 4, local, 50017 Zaragoza. [email protected] RESUMEN La mayoría de los restos fósiles de dinosaurios terópodos de España son dientes aislados y escasos restos postcraneales. La única excepción es el ornitomimosaurio Pelecanimimus polyodon, del Barremiense de Las Hoyas (Cuenca). Hay registro de terópodos en el Jurásico superior (Oxfordiense superior-Tithónico inferior), en el tránsito Jurásico-Cretácico (Tithónico superior- Berriasiense inferior) y en todos los pisos del Cretácico inferior, con excepción del Valanginiense. En el Cretácico superior únicamente hay restos en el Campaniense y Maastrichtiense. La mayor parte de las determinaciones son demasiado generales, lo que impide conocer algunas de las familias que posiblemente estén representadas. Se han reconocido: Neoceratosauria, Baryonychidae, Ornithomimosauria, Dromaeosauridae, además de terópodos indeterminados, y celurosaurios indeterminados (dientes pequeños sin dentículos). La mayoría de los restos son de Maniraptoriformes, siendo especialmente abundantes los dromeosáuridos. Las únicas excepciones son por el momento, el posible Ceratosauria del Jurásico superior de Asturias, los barionícidos del Hauteriviense-Barremiense de Burgos, Teruel y La Rioja, el posible carcharodontosáurido del Aptiense inferior de Morella y el posible abelisáurido del Campaniense de Laño. Además hay algunos terópodos incertae sedis, como los "paronicodóntidos" (entre los que se incluye Euronychodon), y Richardoestesia.
[Show full text]
The Nonavian Theropod Quadrate II: Systematic Usefulness, Major Trends and Cladistic and Phylogenetic Morphometrics Analyses
See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/272162807 The nonavian theropod quadrate II: systematic usefulness, major trends and cladistic and phylogenetic morphometrics analyses Article · January 2014 DOI: 10.7287/peerj.preprints.380v2 CITATION READS 1 90 3 authors: Christophe Hendrickx Ricardo Araujo University of the Witwatersrand Technical University of Lisbon 37 PUBLICATIONS 210 CITATIONS 89 PUBLICATIONS 324 CITATIONS SEE PROFILE SEE PROFILE Octávio Mateus University NOVA of Lisbon 224 PUBLICATIONS 2,205 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Nature and Time on Earth - Project for a course and a book for virtual visits to past environments in learning programmes for university students (coordinators Edoardo Martinetto, Emanuel Tschopp, Robert A. Gastaldo) View project Ten Sleep Wyoming Jurassic dinosaurs View project All content following this page was uploaded by Octávio Mateus on 12 February 2015. The user has requested enhancement of the downloaded file. The nonavian theropod quadrate II: systematic usefulness, major trends and cladistic and phylogenetic morphometrics analyses Christophe Hendrickx1,2 1Universidade Nova de Lisboa, CICEGe, Departamento de Ciências da Terra, Faculdade de Ciências e Tecnologia, Quinta da Torre, 2829-516, Caparica, Portugal. 2 Museu da Lourinhã, 9 Rua João Luis de Moura, 2530-158, Lourinhã, Portugal. s t [email protected] n i r P e 2,3,4,5 r Ricardo Araújo P 2 Museu da Lourinhã, 9 Rua João Luis de Moura, 2530-158, Lourinhã, Portugal. 3 Huffington Department of Earth Sciences, Southern Methodist University, PO Box 750395, 75275-0395, Dallas, Texas, USA.
[Show full text]
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.
[Show full text]
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.
[Show full text]
Tyrannosaurus
Natural Sciences 360 Legacy of Life Lecture 16 Dr. Stuart S. Sumida Theropoda (Including Birds) Recall: Crocodylomorpha Pterosauria Eoraptor Herrerasauridae Saurischia Ornithischia Dinosauria Archosauria THEROPODA •Pronograde bipeds. •Pneumatic (hollow) bones. •Enlarged hand. •Vestigial digits IV and V on hand. •Highly extendable digits I-III on hand. •Compact, elongate, narrow foot – usually missing digit V. Theropod Feet: Note missing V. I IV II III CERATOSAURIA: COELOPHYSOIDEA Difficult to diagnose, as they retain many primitive features: •Pronograde bipeds. •Relatively small. •Skulls are narrow, not boxy in shape. •Many undifferentiated teeth. Best known taxa: Coelophysis Dilolphosaurus “Syntarsus” Dilophosaurus: a crested ceratosaur (No, they didn’t spit.) Coelophysis, skull Coelophysis: reconstructed in northern New Mexico Sauropodomorpha THEROPODA Coelophysoidea Saurischia * Abelisauridae Theropoda Spinosauroidea Allosauroidea Tetanurae Compsognathidae Tyrannosauroidea Coelurosauria Ornithomimosauria Oviraptorisauria Maniraptora Dromaeosauridae Ceratosauria * Troodontidae Avialae CERATOSAURIA: ABELISAURIDAE •Bony outgrowths over the orbits. •Relatively short skull compared to Coelophysoidea. •Blunt snout. •Ornamentation on skull •Reduced forelimbs (like T. rex), but retain a well-developed pectoral girdle. Bony outgrowths over the orbits. Blunt snout. Relatively short skull compared to Coelophysoidea. Carnotaurus Majungatholus Sauropodomorpha THEROPODA Coelophysoidea Saurischia * Abelisauridae Theropoda Spinosauroidea Allosauroidea
[Show full text]
Jurassic- Cretaceous Transition) of Galve (Aragon, NE Spain)
N. Jb. Geol. Palaont. Abh. 239 (1) 77- 99 Stutigart, Januar 2006 A megatheropod tooth from the late Tithonian - middle Berriasian (Jurassic- Cretaceous transition) of Galve (Aragon, NE Spain) JosÃ Ignacio Canudo, JosÃ Ignacio Ruiz-OmeÃ±acaMarc Aurell, JosÃ Luis Barco and Gloria Cuenca-Bescos, Zaragoza With 4 figures and 1 table CANUDO,J. I., RUIZ-OMERACA,J., AURELL,M., BARCO, J. L. & CUENCA-BESCOS,G. (2006): A megatheropod tooth from the late Tithonian - middle Berriasian (Jurassic-Cretaceous transition) of Galve (Aragon, NE Spain). -N. Jb. Geol. Palaont. Abh., 239: 77-99; Stuttgart. Abstract: We herein describe the biggest theropod tooth hitherio found in Spain. The tooth (IPS-G1) comes from the Villar del Arzobispo Formation (Upper Tithonian- Middle Berriasian) in the Galve Sub-basin. The specimen is a nearly complete maxillary tooth with a FABL of 34 mrn and DSDI = 1. Considering its geological age and the crown morphology (including the size), it is most likely that the tooth belongs to an allosauroid. This clade of theropods was present in the Late Jurassic of Portugal and the Early Cretaceous (Bemasian and Barremian) of England. The tooth represents the first allosaurid from Spain, and the biggest theropod from the European Bemasian. Zusammenfassung: Wi beschreiben hier den grofiten bisher in Spanien gefimdenen Theropodenzahn. Dieser Zahn (IPS-G1) stanunt aus der Villar-del-Arzobispo- Formation (spates Tithonium - mittleres Berriasium) im Teilbecken von Galve. Das Exemplar ist ein beinahe vollstandiger Oberkieferzahn mit einer Basislange (FABL) von 34 mm und DSDI = 1. In Anbetracht seines geologischen Alters und der Morphologie der Zahnkrone (auch deren GroOe) stammt der Zahn mit grofier Wahr- scheinlichkeit von einem Allosauroiden.
[Show full text]
Allosauroid (Dinosauria: Theropoda) Phylogeny: Conflict, Consensus, and a New Cladistic Analysis
Edinburgh Research Explorer Phylogeny of Allosauroidea (Dinosauria Citation for published version: Brusatte, SL & Sereno, PC 2008, 'Phylogeny of Allosauroidea (Dinosauria: Theropoda): Comparative analysis and resolution', Journal of Systematic Palaeontology, vol. 6, no. 2, pp. 155-182. https://doi.org/10.1017/S1477201907002404 Digital Object Identifier (DOI): 10.1017/S1477201907002404 Link: Link to publication record in Edinburgh Research Explorer Document Version: Peer reviewed version Published In: Journal of Systematic Palaeontology Publisher Rights Statement: This is an Author's Accepted Manuscript of an article published in Journal of Systematic Palaeontology copyright Taylor & Francis (2008) available online at: http://www.tandfonline.com/ (10.1080/08957950902747411) General rights Copyright for the publications made accessible via the Edinburgh Research Explorer is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policy The University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorer content complies with UK legislation. If you believe that the public display of this file breaches copyright please contact [email protected] providing details, and we will remove access to the work immediately and investigate your claim. Download date: 27. Sep. 2021 Authors Post-Print Version. Final article was published in Journal of Systematic Palaeontology by Taylor and Francis (2008) Cite As: Brusatte, SL & Sereno, PC 2008, 'Phylogeny of Allosauroidea (Dinosauria: Theropoda): Comparative analysis and resolution' Journal of Systematic Palaeontology, vol 6, no. 2, pp. 155- 182. DOI: 10.1017/S1477201907002404 PHYLOGENY OF ALLOSAUROIDEA (DINOSAURIA: THEROPODA): COMPARATIVE ANALYSIS AND RESOLUTION Stephen L.
[Show full text]
An Inventory of Non-Avian Dinosaurs from National Park Service Areas
Lucas, S.G. and Sullivan, R.M., eds., 2018, Fossil Record 6. New Mexico Museum of Natural History and Science Bulletin 79. 703 AN INVENTORY OF NON-AVIAN DINOSAURS FROM NATIONAL PARK SERVICE AREAS JUSTIN S. TWEET1 and VINCENT L. SANTUCCI2 1National Park Service, 9149 79th Street S., Cottage Grove, MN 55016 -email: [email protected]; 2National Park Service, Geologic Resources Division, 1849 “C” Street, NW, Washington, D.C. 20240 -email: [email protected] Abstract—Dinosaurs have captured the interest and imagination of the general public, particularly children, around the world. Paleontological resource inventories within units of the National Park Service have revealed that body and trace fossils of non-avian dinosaurs have been documented in at least 21 National Park Service areas. In addition there are two historically associated occurrences, one equivocal occurrence, two NPS areas with dinosaur tracks in building stone, and one case where fossils have been found immediately outside of a monument’s boundaries. To date, body fossils of non- avian dinosaurs are documented at 14 NPS areas, may also be present at another, and are historically associated with two other parks. Dinosaur trace fossils have been documented at 17 NPS areas and are visible in building stone at two parks. Most records of NPS dinosaur fossils come from park units on the Colorado Plateau, where body fossils have been found in Upper Jurassic and Lower Cretaceous rocks at many locations, and trace fossils are widely distributed in Upper Triassic and Jurassic rocks. Two NPS units are particularly noted for their dinosaur fossils: Dinosaur National Monument (Upper Triassic through Lower Cretaceous) and Big Bend National Park (Upper Cretaceous).
[Show full text]
The Early Origin of Feathers
Trends in Ecology & Evolution Review The Early Origin of Feathers Michael J. Benton,1,* Danielle Dhouailly,2 Baoyu Jiang,3 and Maria McNamara4 Feathers have long been regarded as the innovation that drove the success of Highlights birds. However, feathers have been reported from close dinosaurian relatives of Feathers are epidermal appendages birds, and now from ornithischian dinosaurs and pterosaurs, the cousins of dino- comprising mostly corneous β-proteins saurs. Incomplete preservation makes these reports controversial. If true, these (formerly β-keratins), and are characteris- tic of birds today. findings shift the origin of feathers back 80 million years before the origin of birds. Gene regulatory networks show the deep homology of scales, feathers, and hairs. There are close connections in terms of Hair and feathers likely evolved in the Early Triassic ancestors of mammals and genomic regulation between numerous birds, at a time when synapsids and archosaurs show independent evidence of regularly arrayed structures in the epider- mis, including denticles in sharks, dermal higher metabolic rates (erect gait and endothermy), as part of a major resetting of scales in teleost fish, epidermal scales in terrestrial ecosystems following the devastating end-Permian mass extinction. reptiles, feathers in birds, and hairs in mammals. Early Origin of Feathers The discovery that genes specifictothe It is shocking to realise that feathers originated long before birds because feathers have generally production of feathers evolved at the – base of Archosauria rather than the been regarded as the key avian innovation [1 4]. However, thousands of astonishing fossils from base of Aves or Avialae (birds) is China have shown that many nonavian dinosaurs (see Glossary) also had feathers, including matched by fossil evidence that feathers feather types not found in birds today.
[Show full text]
The Dinosaurs (Carnosaurs, Allosaurids, Sauropods, Cetiosaurids) of the Middle Jurassic of Cerro Cóndor (Chubut, Argentina)*
Annales de Paléontologie (Vert.-Invert.) 1986, vol. 72, no. 4, pp. 325-386. ______ THE DINOSAURS (CARNOSAURS, ALLOSAURIDS, SAUROPODS, CETIOSAURIDS) OF THE MIDDLE JURASSIC OF CERRO CÓNDOR (CHUBUT, ARGENTINA)* by J. F. BONAPARTE ________ Key-words: Dinosaurs. Carnosauria. Allosauridae. Sauropoda. Cetiosauridae. Anatomy. Middle Jurassic. Argentina. * CONICET MACN, Museo “B. Rivadavia”, Avenida Angel Gallardo 470, 1405 Buenos Aires, Argentina. Translation: B. LANGE-BADRE. * Original citation: Bonaparte, J. F. 1986. Les dinosaures (Carnosaures, Allosauridés, Sauropodes, Cétosauridés) du Jurassique Moyen de Cerro Cóndor (Chubut, Argentina). Annales de Paléontologie (Vert.-Invert.) 72(3):247- 289. Translated by Matthew Carrano, University of Chicago, October 1995. Abstract. - The stratigraphy and the dinosaurs of the Middle Jurassic (Callovian of Cerro Cóndor) of west-central Chubut province (Patagonia, Argentina) are briefly described. Piatnitzkysaurus floresi Bonaparte (1979) is an allosaurid carnosaur known from a large part of the skeleton. The basicranium of this species is different from that of Allosaurus fragilis, Ceratosaurus nasicornis, Acrocanthosaurus atokensis, Piveteausaurus divesensis and Dilophosaurus wetherilli and shows some similarities to that of Eustreptospondylus oxoniensis. The postcranial skeleton has similarities to that of Allosaurus fragilis, although it has many plesiomorphic characters relative to the North American species: the pubis has a completely closed obturator foramen and a less developed distal process; the femur is directed anteromedially at its head and not medially as in A. fragilis; the tibia is more gracile and the cnemial crest less developed in Piatnitzkysaurus floresi. Many elements of the postcranial skeleton are hollowed by pneumatic cavities. Patagosaurus fariasi Bonaparte (1979) is a cetiosaurid sauropod represented by several incomplete specimens, providing considerable information about the postcranial skeleton.
[Show full text]
A New Specimen of Acrocanthosaurus Atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA
A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA Philip J. CURRIE Royal Tyrrell Museum of Palaeontology, Box 7500, Drumheller, Alberta T0J 0Y0 (Canada) [email protected] Kenneth CARPENTER Denver Museum of Natural History, Department of Earth Sciences, City Park, Denver, Colorado 80205 (USA) [email protected] Currie P. J. & Carpenter K. 2000. — A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA. Geodiversitas 22 (2) : 207-246. The data matrix is available at http://www.mnhn.fr/publication/matadd/g00n2a3.html ABSTRACT A new skeleton of Acrocanthosaurus atokensis is the most complete specimen collected and has the only known complete skull. Aspects of the new skeleton are described in detail, with special attention directed to the morphology of the skull and forelimb. Although unquestionably one of the largest theropods ever found, it is smaller than Carcharodontosaurus, Giganotosaurus and Tyrannosaurus. Comparison with other theropods suggests that Acrocanthosaurus bears a strong resemblance to these taxa because of charac- KEY WORDS ters that are size determinate, and the evidence suggests Acrocanthosaurus is Dinosaurs, more closely related to Allosauridae than to Carcharodontosauridae. Three theropods, Early Cretaceous, families (Allosauridae, Carcharodontosauridae, Sinraptoridae) are recognized USA. in the Allosauroidea. GEODIVERSITAS • 2000 • 22 (2) © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. www.mnhn.fr/publication/ 207 Currie P. J. & Carpenter K. RÉSUMÉ Un nouveau specimen d’Acrocanthosaurus atokensis (Theropoda, Dinosauria) du Crétacé inférieur de la Formation Antlers (Crétacé inférieur, Aptien) de l’Oklahoma, États-Unis.
[Show full text]
Tyrannosaurids (Dinosauria) of Asia and North America
Aspects of Nonmarine Cretaceous Geology Tyrannosaurids (Dinosauria) of Asia and North America KENNETH CARPENTER Oklahoma Museum of Natural History, University of Oklahoma, Norman, Oklahoma 73019, U.S. A. * ' ABSTRACT The theropod family Tyrannosauridae (Dinosauria) is composed of four genera and seven species. All taxa are known from nearly complete skeletons and/or skulls, thus making it one of the best documented large theropod families. The stratigraphic and palaeobiogeographic distribution of the Tyrannosauridae extends from the lower Campanian to upper Maastrichtian of North America,and to the Campanian-Maas- trichtian of Asia. INTRODUCTION Tyrannosaurid theropods are known only from the Upper Cretaceous of Asia and North America. Their earliest record is a fragmentary skeleton (genus unknown) from the lower Campanian Eagle Ford Sandstone of Montana (U.S.A. ) (Gilmore, 1920). By the upper Campanian, however, tyrannosaurids occur through out the western Interior and Gulf Coast of North America. They are known to have survived until the latest Maastrichtian in the Western Interior. In Asia, tyran nosaurids are known only from the Nemegt Formation estimated to be Campanian- Maastrichtian in age (Fox, 1978). Their apparent absence from upper Maastrichtian deposits in Asia is probably not due to extinction, but due to the lack of upper Maas trichtian deposits. The earliest tyrannosaurids described were the result of explorations by the geo logical surveys of Canada and the United States. The first specimen consisted of sev eral isolated and scattered teeth collected from the Judith River Formation of Mon tana. These were the first theropod teeth found in North America and were named Deinodon horridusby Leidy (1857).
[Show full text]