Allosaurus Fossil range: Late Jurassic
Replica of an Allosaurus fragilis skull. The Late Jurassic (or Malm) Epoch of the Jurassic Period is the unit of geologic time from 161
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Sauropsida Superorder: Dinosauria Order: Saurischia Suborder: Theropoda Infraorder: Carnosauria Family: Allosauridae Genus: Allosaurus Marsh, 1877
Species
A. Chordates ( Phylum Chordata) are a group of Animals that includes the Vertebrates together with several closely related Invertebrates Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers Saurischia (sɔːˈrɪskiə, from the Greek sauros ( σαυρος) meaning 'lizard' and ischion ( ισχιον) meaning 'hip joint' Theropods (ˈθɪərəpɒd theropoda /θiːˈrɒpədə/ 'beast feet' are a group of Bipedal Saurischian Dinosaurs Although they were primarily Carnosauria is a group of large Predatory Dinosaurs that lived during the Jurassic and Cretaceous periods Allosauridae was a family of medium to large sized carnivorous Theropod Dinosaurs They lived during the Late Jurassic and Early Cretaceous Othniel Charles Marsh ( October 29, 1831 &ndash March 18, 1899) was one of the pre-eminent Paleontologists of the 19th century who In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. fragilis Marsh, 1877 (type) ?A. In biology a type is that which fixes a name to a Taxon. Depending on the nomenclature code which is applied to the organism in question a type may be a specimen europaeus Mateus et al. , 2006 A. "jimmadseni" Chure, 2000 vide Glut, 2003 (nomen nudum) ?A. Donald F Glut is an American Writer, Motion picture director, Screenwriter, Amateur paleontologist, Musician The phrase nomen nudum is a Latin term meaning "naked name" tendagurensis Janensch, 1925
Synonyms
Creosaurus Marsh, 1878 Labrosaurus Marsh, 1879 ?Antrodemus Leidy, 1870 ?Apatodon Marsh, 1877 ?Epanterias Cope, 1878

Allosaurus (pronounced /ˌæləˈsɔrəs/) is a genus of large theropod dinosaur that lived 155 to 145 million years ago, in the late Jurassic period. Werner Ernst Martin Janensch ( November 11, 1878 in Herzberg (Elster - October 20, 1969 in Berlin) was a German In Scientific nomenclature, synonyms are different Scientific names used for a single Taxon. Antrodemus valens is a scientific name assigned by American Paleontologist Joseph Leidy in 1870 to a very fragmentary Allosaurid fossil Joseph Leidy ( September 9 1823 &ndash 30 April 1891) was an American Paleontologist. Epanterias is a Genus of theropod Dinosaur from the Kimmeridgian - Tithonian -age Upper Jurassic Morrison Edward Drinker Cope (July 28 1840&ndashApril 12 1897 was an American paleontologist and comparative anatomist, as well as a noted herpetologist A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic Theropods (ˈθɪərəpɒd theropoda /θiːˈrɒpədə/ 'beast feet' are a group of Bipedal Saurischian Dinosaurs Although they were primarily The Late Jurassic (or Malm) Epoch of the Jurassic Period is the unit of geologic time from 161 The first remains that can definitely be ascribed to this genus were described in 1877 by Othniel Charles Marsh. Othniel Charles Marsh ( October 29, 1831 &ndash March 18, 1899) was one of the pre-eminent Paleontologists of the 19th century who As one of the first well-known theropod dinosaurs, it has long attracted attention outside of paleontological circles, and has been a lead dinosaur in several films and documentaries. Palaeontology redirects here For the Scientific journal, see Palaeontology (journal. Documentary film is a broad category of visual expression that is based on the attempt in one fashion or another to " Document " reality

Allosaurus was a large bipedal predator with a large skull, equipped with dozens of large, sharp teeth. Bipedalism is a form of Terrestrial locomotion where an organism moves by means of its two rear limbs It averaged 8. 5 meters (30 ft) in length, though fragmentary remains suggest it could have reached over 12 meters (39 ft). The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International A foot (plural feet or foot; symbol or abbreviation ft or sometimes &prime – the prime symbol) is a non-SI unit Relative to the large and powerful hindlimbs, its three-fingered forelimbs were small, and the body was balanced by a long, heavy tail. It is classified as an allosaurid, a type of carnosaurian theropod dinosaur. Allosauridae was a family of medium to large sized carnivorous Theropod Dinosaurs They lived during the Late Jurassic and Early Cretaceous The genus has a complicated taxonomy, and includes an uncertain number of valid species, the best known of which is A. Taxonomy is the practice and science of classification The word comes from the Greek, taxis (meaning 'order' 'arrangement' and, nomos In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. fragilis. The bulk of Allosaurus remains have come from North America's Morrison Formation, with material also from Portugal and possibly Tanzania. The Morrison Formation is a distinctive sequence of Late Jurassic Sedimentary rock that is found in the western United States which has been the most fertile source Portugal, officially the Portuguese Republic (República Portuguesa is a country on the Iberian Peninsula. Tanzania ˌtænzəˈniːə officially the United Republic of Tanzania (Jamhuri ya Muungano wa Tanzania is a country in East Africa bordered by Kenya It was known for over half of the 20th century as Antrodemus, but study of the copious remains from the Cleveland Lloyd Dinosaur Quarry brought the name Allosaurus back to prominence, and established it as one of the best-known dinosaurs. Antrodemus valens is a scientific name assigned by American Paleontologist Joseph Leidy in 1870 to a very fragmentary Allosaurid fossil The Cleveland Lloyd Dinosaur Quarry National Natural Landmark (designated a National Natural Landmark in 1966) is located on a gravel road about 30 miles

As the prominent large predator in the Morrison Formation, Allosaurus was at the top of the food chain, probably preying on contemporaneous large herbivorous dinosaurs. The Morrison Formation is a distinctive sequence of Late Jurassic Sedimentary rock that is found in the western United States which has been the most fertile source Food chains, also called food networks and/or trophic networks, describe the feeding relationships between species within an Ecosystem. Potential prey included ornithopods, stegosaurids, and sauropods. Ornithopods (ɔrˈnɪθoʊpɒd are a group of bird-hipped Dinosaurs that started out as small Bipedal running grazers and grew in size and Known colloquially as stegosaurs the Stegosauria are a group of herbivorous Dinosaurs of the Jurassic and Early Cretaceous Periods Sauropoda (sɔˈrɒpədə or the sauropods (/ˈsɔroʊpɒd/ are a suborder or infraorder of the Saurischian ("lizard-hipped" While it is often thought of as preying on sauropod dinosaurs in groups, there is little evidence for cooperative social behavior in this genus, and individuals may have been aggressive toward each other instead. In Biology, Psychology and Sociology social behavior is behavior directed towards society or taking place between members of the same species It may have attacked large prey by ambush, using its upper jaws like a hatchet. See Hatchet (novel for the Young adult novel. See Hatchet (film for the Horror film.

Contents 1 Description 1.1 Skull 1.2 Postcranial skeleton 2 Classification 3 Discovery and history 3.1 Early discoveries and research 3.2 Cleveland-Lloyd discoveries 3.3 Recent work: 1980s–present 3.3.1 "Big Al" 4 Species and taxonomy 5 Paleoecology 6 Paleobiology 6.1 Life history 6.2 Feeding 6.3 Social behavior 6.4 Brain and senses 7 In popular culture 8 References 9 External links

Description

Allosaurus was a typical large theropod, having a massive skull on a short neck, a long tail and reduced forelimbs. The neck is the part of the Body on many limbed Vertebrates that distinguishes the head from the Torso or trunk The tail is the section at the rear end of an Animal 's Body; in general the term refers to a distinct flexible Appendage to the Torso. Allosaurus fragilis, the best-known species, had an average length of 8. 5 meters (28 ft),^[1] with the largest definitive Allosaurus specimen (AMNH 680) estimated at 9. The American Museum of Natural History ( AMNH) located on the Upper West Side, Manhattan, New York, USA is one of the largest and most 7 meters long (32 ft),^[2] and an estimated weight of 2. 3 metric tons (2. This article is about the tonne or metric ton For other tons see Ton. 5 short tons). The short ton ( S/T) is a unit of mass equal to 2000 lb (around 907 ^[2] In his 1976 monograph on Allosaurus, James Madsen mentioned a range of bone sizes which he interpreted to show a maximum length of 12 to 13 meters (40 to 43 ft). A monograph ( Classical Greek, "One Writer" or "Single Writing") is a work of writing upon a single subject usually also by a single ^[3] As with dinosaurs in general, weight estimates are debatable, and since 1980 have ranged between 1500 kilograms (3300 lb), 1000 to 4000 kilograms (2200 to 8800 lb), and 1010 kilograms (2230 lb) for modal adult weight (not maximum). In Statistics, the mode is the value that occurs the most frequently in a Data set or a Probability distribution. ^[4]

Several gigantic specimens have been attributed to Allosaurus, but may in fact belong to other genera. The closely related genus Saurophaganax (OMNH 1708) reached perhaps 10. Saurophaganax ("lizard-eating master" is a Genus of Allosaurid Dinosaur from the Morrison Formation of Jurassic The Sam Noble Oklahoma Museum of Natural History is a Natural history Museum in Norman Oklahoma, operated by the University of Oklahoma. 9 meters (36 ft) in length,^[2] and its single species has sometimes been included in the genus Allosaurus as Allosaurus maximus, though recent studies support it as a separate genus. ^[5] Another potential specimen of Allosaurus, once assigned to the genus Epanterias (AMNH 5767), may have measured 12. Epanterias is a Genus of theropod Dinosaur from the Kimmeridgian - Tithonian -age Upper Jurassic Morrison 1 meters in length (40 ft). ^[2]

Skull

The skull and teeth of Allosaurus were modestly proportioned for a theropod of its size. Paleontologist Gregory S. Paul gives a length of 845 millimeters (33. Gregory S Paul (born 1954) is a Freelance Paleontologist, Author and Illustrator. The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to 3 in) for a skull belonging to an individual he estimates at 7. 9 meters long (26 ft). ^[6] Each premaxilla (the bones that formed the tip of the snout), held five teeth with D-shaped cross-sections, and each maxilla (the main tooth-bearing bones in the upper jaw) had between fourteen and seventeen teeth; the number of teeth does not exactly correspond to the size of the bone. The premaxilla is a pair of small Cranial bones at the very tip of the jaws of many animals usually bearing Teeth, but not always This article is about the Mammal maxilla For Arthropod maxillae see Mouthparts; for Insect maxillae in particular see Insect mouthparts Each dentary (the tooth-bearing bone of the lower jaw) had between fourteen and seventeen teeth, with an average count of sixteen. The mandible (from Latin mandibula, "jawbone" or inferior maxillary bone forms the lower Jaw and holds the lower teeth in place The teeth became shorter, more narrow, and more curved toward the back of the skull. All of the teeth had saw-like edges. They were shed easily, and were replaced continually, making them common fossils. ^[3]

The skull had a pair of horns above and in front of the eyes. A horn is a pointed projection of the Skin on the head of various Mammals consisting of a covering of horn ( Keratin and other Proteins These horns were composed of extensions of the lacrimal bones,^[3] and varied in shape and size. The lacrimal bone, the smallest and most fragile Bone of the face is situated at the front part of the medial wall of the orbit. There were also lower paired ridges running along the top edges of the nasal bones that led into the horns. The nasal bones are two small oblong Bones varying in size and form in different individuals they are placed side by side at the middle and upper part of the Face ^[3] The horns were probably covered in a keratin sheath and may have had a variety of functions, including acting as sunshades for the eye,^[3] being used for display, and being used in combat against other members of the same species^[7][6] (although they were fragile). Keratins are a family of fibrous structural proteins; tough and insoluble they form the hard but nonmineralized structures found in Reptiles Birds ^[3] There was a ridge along the back of the skull roof for muscle attachment, as is also seen in tyrannosaurids. Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards" is a family of Coelurosaurian Theropod Dinosaurs which ^[6]

Inside the lacrimal bones were depressions that may have held glands, such as salt glands. A gland is an organ in an animal's body that synthesizes a substance for release such as Hormones or Breast milk, often into the Bloodstream The salt gland is an organ for excreting excess Salt. It is found in Elasmobranchs marine Birds and some Reptiles In Sharks ^[8] Within the maxillae were sinuses that were better developed than those of more basal theropods such as Ceratosaurus and Marshosaurus; they may have been related to the sense of smell, perhaps holding something like Jacobson's organ. The maxillary sinus (or Antrum of Highmore) is the largest of the Paranasal sinuses and is pyramidal in shape In Phylogenetics, a basal Clade is the earliest clade to branch in a larger clade it appears at the base of a cladogram Ceratosaurus (ˌsɛrətəˈsɔrəs meaning 'horned lizard' in reference to the horn on its nose ( Greek κερας/κερατος keras/keratos meaning Marshosaurus was a genus of medium sized theropod, with a size up to 5 or 6 meters in length and a skull about 60 cm long Olfaction (also known as olfactics or smell) refers to the Sense of smell. The vomeronasal organ ( VNO) or Jacobson's organ, is an auxiliary Olfactory Sense organ that is found in many Animals It was The roof of the braincase was thin, perhaps to improve thermoregulation for the brain. Thermoregulation is the ability of an Organism to keep its body temperature within certain boundaries even when temperature surrounding is very different The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain ^[3] The skull and lower jaws had joints that permitted motion within these units. In the lower jaws, the bones of the front and back halves loosely articulated, permitting the jaws to bow outward and increasing the animal's gape. ^[9] The braincase and frontals may also have had a joint. The frontal bone is a Bone in the Human Skull that resembles a cockleshell in form and consists of two portions a vertical ^[3]

Postcranial skeleton

Allosaurus had nine vertebrae in the neck, fourteen in the back, and five in the sacrum supporting the hips. A vertebra (plural vertebrae) is an individual Irregular bone in the spinal or Vertebral column ( aka ischis a flexuous and flexible column The sacrum is a large triangular bone at the base of the spine and at the upper and back part of the Pelvic cavity, where it is inserted like a wedge between ^[10] The number of tail vertebrae is unknown and varied with individual size; James Madsen estimated about 50,^[3] while Gregory S. Paul considered that to be too many and suggested 45 or less. ^[6] There were hollow spaces in the neck and anterior back vertebrae. In fields of Anatomy, anatomical terms of location are descriptive terms to help identify relative positions or directions within a species ^[3] Such spaces, which are also found in modern theropods (that is, the birds), are interpreted as having held air sacs used in respiration. Bird anatomy, or the physiological structure of Birds In living organisms a respiratory system functions to allow Gas exchange. ^[11] The rib cage was broad, giving it a barrel chest, especially in comparison to less derived theropods like Ceratosaurus. In Phylogenetics, a trait is derived if it is present in an organism but was absent in the last common ancestor of the group being considered ^[12] Allosaurus had gastralia (belly ribs), but these are not common findings,^[3] and they may have ossified poorly. Gastralia (singular gastralium) are Dermal bones found in the ventral body wall of Crocodilian and Sphenodon species Ossification is the process of Bone formation in which connective tissues such as Cartilage are turned to bone or bone-like tissue ^[6] In one published case, the gastralia show evidence of injury during life. ^[13] A furcula (wishbone) was also present, but has only been recognized since 1996; in some cases furculae were confused with gastralia. The furcula (" little fork " in Latin is a forked Bone found in Birds and Theropod Dinosaurs formed by the fusion of the two ^[14][13] The ilium, the main hip bone, was massive, and the pubic bone had a prominent foot that may have been used for both muscle attachment and as a prop for resting the body on the ground. The ilium of the Pelvis is divisible into two parts the body and the ala the separation is indicated on the top surface by a curved line the arcuate line and on the For the bone in many mammals often called the penis bone see Baculum The android pubic bone is the Ventral and Anterior Madsen noted that in about half of the individuals from the Cleveland Lloyd Dinosaur Quarry, independent of size, the pubes had not fused to each other at their foot ends. He suggested that this was a sexual characteristic, with females lacking fused bones to make egg-laying easier. Sexual dimorphism is the systematic difference in form between individuals of different Sex in the same Species. ^[3] This proposal has not attracted further attention, however.

The forelimbs of Allosaurus were short in comparison to the hindlimbs (only about 35% the length of the hindlimbs in adults)^[15] and had three fingers per hand, tipped with large, strongly curved and pointed claws. ^[3] The arms were powerful,^[6] and the forearm was somewhat shorter than the upper arm (1:1. 2 humerus/ulna ratio). The humerus is a Long bone in the Arm or Forelimb that runs from the Shoulder to the Elbow. The ulna ( elbow bone) is a long bone prismatic in form placed at the medial side of the Forearm, parallel with the radius. ^[16] The wrist had a version of the semilunate carpal^[17] also found in more derived theropods like maniraptorans. In Tetrapods the carpus is the sole cluster of the Bones in the Wrist between the radius and Ulna and the Metacarpus Maniraptora ("hand snatchers" is a Clade of Coelurosaurian Dinosaurs which includes the Birds and the dinosaurs that were more closely Of the three fingers, the innermost (or thumb) was the largest,^[6] and diverged from the others. The thumb is the medial -most digit of the hand The English adjective for thumb is pollical ^[16] The legs were not as long or suited for speed as those of tyrannosaurids, and the claws of the toes were less developed and more hoof-like than those of earlier theropods. Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards" is a family of Coelurosaurian Theropod Dinosaurs which HoofRearHoovesjpg|thumb|200px|right|Rear hooves of a horse]] A hoof is the tip of a Toe of an Ungulate Mammal, strengthened by a thick horny ( ^[6] Each foot had three weight-bearing toes and an inner dewclaw, which Madsen suggested could have been used for grasping in juveniles. A dewclaw is a vestigial digit of the Foot of many Mammals Birds and Reptiles (including some extinct orders like certain ^[3] There was also what is interpreted as the splint-like remnant of a fifth (outermost) metatarsal, perhaps used as a lever between the Achilles tendon and foot. The metatarsus consists of the five long Bones of the Foot, which are numbered from the medial side ( ossa metatarsalia I The Achilles tendon (or occasionally Achilles’ tendon) also known as the calcaneal tendon or the tendocalcaneous, is a Tendon of the posterior ^[18]

Classification

Allosaurus was an allosaurid, a member of a family of large theropods within the larger group Carnosauria. In Biological classification, family ( Latin Carnosauria is a group of large Predatory Dinosaurs that lived during the Jurassic and Cretaceous periods The family name Allosauridae was created for this genus in 1878 by Othniel Charles Marsh,^[19] but the term was largely unused until the 1970s in favor of Megalosauridae, another family of large theropods that eventually became a wastebasket taxon. Allosauridae was a family of medium to large sized carnivorous Theropod Dinosaurs They lived during the Late Jurassic and Early Cretaceous Othniel Charles Marsh ( October 29, 1831 &ndash March 18, 1899) was one of the pre-eminent Paleontologists of the 19th century who Megalosauridae was a family of relatively primitive tetanuran theropod dinosaurs order Saurischia. Wastebasket taxon (also called a wastebin taxon or dustbin taxon) is a term used in taxonomic circles to refer to a Taxon that has the sole purpose This, along with the use of Antrodemus for Allosaurus during the same period, is a point that needs to be remembered when searching for information on Allosaurus in publications that predate James Madsen's 1976 monograph. Major publications using the name Megalosauridae instead of Allosauridae include Gilmore, 1920,^[16] von Huene, 1926,^[20] Romer, 1956 and 1966,^[21][22] Steel, 1970,^[23] and Walker, 1964. Charles Whitney Gilmore (1874-1945 was an American paleontologist, who named Dinosaurs in North America and Mongolia, including the Friedrich von Huene ( March 22, 1875 &ndash April 4, 1969) was a German Paleontologist who named more Dinosaurs Alfred Sherwood Romer ( December 28, 1894 - November 5, 1973) was an American Paleontologist and comparative Anatomist and Alick Walker ( October 26, 1925 - December 4, 1999) was a British Palaeontologist, after whom the Alwalkeria ^[24]

Following the publication of Madsen's influential monograph, Allosauridae became the preferred family assignment, but it too was not strongly defined. Semi-technical works used Allosauridae for a variety of large theropods, usually those that were larger and better-known than megalosaurids. Typical theropods that were thought to be related to Allosaurus included Indosaurus, Piatnitzkysaurus, Piveteausaurus, Yangchuanosaurus,^[25] Acrocanthosaurus, Chilantaisaurus, Compsosuchus, Stokesosaurus, and Szechuanosaurus. Indosaurus (meaning "Indian lizard" is a Genus of Theropod Dinosaur in what is now India. Piatnitzkysaurus is the name given to a Genus of Megalosaurid Dinosaur. Piveteausaurus is a Genus of Megalosaurid Dinosaur from the Middle Jurassic of Europe known largely from a fossilized braincase Yangchuanosaurus was a Theropod Dinosaur that lived in China during the Late Jurassic period, and was similar in size and appearance Acrocanthosaurus (, meaning 'high-spined lizard' is a Genus of Allosauroid Theropod Dinosaur that existed in what is now North Chilantaisaurus ("Ch'i-lan-t'ai lizard" was a possible spinosauroid Dinosaur from early Cretaceous China. Compsosuchus (meaning "pretty crocodile" is an Extinct Genus of Abelisaurian Dinosaur. Stokesosaurus ("Stokes' lizard" is a Genus of small (around 3 to 4 meters in length early Tyrannosaur from the Late Jurassic Szechuanosaurus (" Szechuan lizard" is a Genus of Sinraptorid Dinosaur from the Late Jurassic. ^[26] Given modern knowledge of theropod diversity and the advent of cladistic study of evolutionary relationships, none of these theropods is now recognized as an allosaurid, although several, like Acrocanthosaurus and Yangchuanosaurus, are members of related families. eVolution is the third Album by eLDee, it was due to be released in 2008 ^[11]

Allosauridae is one of three families in Carnosauria; the other two are Carcharodontosauridae and Sinraptoridae. Carcharodontosaurids (from the Greek Carcharodontosauros: "shark-toothed lizards" were a group of carnivorous Theropod Dinosaurs Sinraptorids were a family of carnivorous Theropod Dinosaurs They tended to be large Predators some growing to sizes of 30 ft (10 ^[11] Allosauridae has at times been proposed as ancestral to the Tyrannosauridae (which would make it paraphyletic), one recent example in Gregory S. Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards" is a family of Coelurosaurian Theropod Dinosaurs which In Phylogenetics, a group of organisms is said to be paraphyletic if the group contains its most recent common ancestor but does not contain all Paul's Predatory Dinosaurs of the World,^[27] but this has been rejected, with tyrannosaurids identified as members of a separate branch of theropods, the Coelurosauria. For the prehistoric gliding reptile see Coelurosauravus. Coelurosauria (sɨˌljʊərəˈsɔriə is defined as the clade containing all Theropod ^[28] Allosauridae is the smallest of the carnosaur families, with only Saurophaganax and a currently unnamed French allosauroid accepted as possible valid genera besides Allosaurus in the most recent review. This article is about the country For a topic outline on this subject see List of basic France topics. Allosauroidea is a superfamily or Clade of Theropod Dinosaurs which contains three families — the Sinraptoridae, Carcharodontosauridae A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic ^[11] Another genus, Epanterias, is a potential valid member, but it and Saurophaganax may turn out to be large examples of Allosaurus. ^[6] Recent reviews have kept the genus Saurophaganax and included Epanterias with Allosaurus. ^[4][11]

Discovery and history

Early discoveries and research

The discovery and early study of Allosaurus is complicated by the multiplicity of names coined during the Bone Wars of the late 1800s. The Bone Wars is the name given to a period of intense fossil speculation and discovery during the Gilded Age of American history marked by a heated rivalry between Edward The first described fossil in this history was a bone obtained secondhand by Ferdinand Vandiveer Hayden in 1869. FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. Dr Ferdinand Vandeveer Hayden ( September 7, 1829 – December 22, 1887) was an American Geologist noted for his pioneering It came from Middle Park, near Granby, Colorado, probably from Morrison Formation rocks. Middle Park (elev 8000 ft/2500 m is a high basin in the Rocky Mountains of north-central Colorado in the United States The Town of Granby is a Statutory Town that is the most populous town in Grand County, Colorado, United States. The Morrison Formation is a distinctive sequence of Late Jurassic Sedimentary rock that is found in the western United States which has been the most fertile source The locals had identified such bones as "petrified horse hoofs". The horse ( Equus caballus) is a hoofed ( Ungulate) Mammal, one of eight living species of the family Equidae. Hayden sent his specimen to Joseph Leidy, who identified it as half of a tail vertebra, and tentatively assigned it to the European dinosaur genus Poekilopleuron as Poicilopleuron [sic] valens. Joseph Leidy ( September 9 1823 &ndash 30 April 1891) was an American Paleontologist. Poekilopleuron is an Extinct Genus of large basal tetanuran Theropod dinosaur pertaining to the Clade Megalosauroidea ^[29] He later decided it deserved its own genus, Antrodemus. ^[30]

Allosaurus itself is based on YPM 1930, a small collection of fragmentary bones including parts of three vertebrae, a rib fragment, a tooth, a toe bone, and, most useful for later discussions, the shaft of the right humerus (upper arm). A holotype is one of several possible Biological types A type is what fixes a name to a Taxon. The Peabody Museum of Natural History at Yale University is among the oldest largest and most prolific university natural history museums in the world Othniel Charles Marsh gave these remains the formal name Allosaurus fragilis in 1877. Allosaurus comes from the Greek allos/αλλος, meaning "strange" or "different" and saurus/σαυρος, meaning "lizard" or "reptile". The Ancient Greek language is the historical stage in the development of the Hellenic language family spanning the Archaic (c ^[31] It was named 'different lizard' because its vertebrae were different from those of other dinosaurs known at the time of its discovery. ^[32][33] The species epithet fragilis is Latin for "fragile", referring to lightening features in the vertebrae. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. The bones were collected from the Morrison Formation of Garden Park, north of Cañon City. Garden Park, in southcentral Colorado, is known for its Jurassic dinosaurs and the role the specimens played in the infamous Bone wars of the late For other similar names see also Canyon City. The City of Cañon City (ˈkænjən ˈsɪti ^[32] Marsh and Edward Drinker Cope, who were in scientific competition, went on to coin several other genera based on similarly sparse material that would later figure in the taxonomy of Allosaurus. Edward Drinker Cope (July 28 1840&ndashApril 12 1897 was an American paleontologist and comparative anatomist, as well as a noted herpetologist These include Marsh's Creosaurus^[19] and Labrosaurus,^[34] and Cope's Epanterias. ^[35]

In their haste, Cope and Marsh did not always follow up on their discoveries (or, more commonly, those made by their subordinates). For example, after the discovery by Benjamin Mudge of the type specimen of Allosaurus in Colorado, Marsh elected to concentrate work in Wyoming; when work resumed at Garden Park in 1883, M. Benjamin Franklin Mudge ( August 11 1817 &ndash November 21 1879) was an American Lawyer, Geologist and The State of Wyoming ( is a sparsely populated state in the western region of the United States. P. Felch found an almost complete Allosaurus and several partial skeletons. ^[8] In addition, one of Cope's collectors, H. F. Hubbell, found a specimen in the Como Bluff area of Wyoming in 1879, but apparently did not mention its completeness, and Cope never unpacked it. Como Bluff is a long ridge extending east-west located between the towns of Rock River and Medicine Bow, Wyoming. Upon unpacking in 1903 (several years after Cope had died), it was found to be one of the most complete theropod specimens then known, and in 1908 the skeleton, now cataloged as AMNH 5753, was put on public view. ^[36] This is the well-known mount poised over a partial Apatosaurus skeleton as if scavenging it, illustrated as such by Charles R. Scavenging, or necrophagy, is a Carnivorous Feeding behaviour in which a predator consumes Corpses or Carrion that were killed Knight. Although notable as the first free-standing mount of a theropod dinosaur, and often illustrated and photographed, it has never been scientifically described. ^[37]

The multiplicity of early names complicated later research, with the situation compounded by the terse descriptions provided by Marsh and Cope. Even at the time, authors such as Samuel Wendell Williston suggested that too many names had been coined. Samuel Wendell Williston ( July 10, 1852 &ndash August 30, 1918) was an American Educator and Paleontologist who was the ^[38] For example, Williston pointed out in 1901 that Marsh had never been able to adequately distinguish Allosaurus from Creosaurus. ^[39] The most influential early attempt to sort out the convoluted situation was produced by Charles W. Gilmore in 1920. Charles Whitney Gilmore (1874-1945 was an American paleontologist, who named Dinosaurs in North America and Mongolia, including the He came to the conclusion that the tail vertebra dubbed Antrodemus by Leidy was indistinguishable from those of Allosaurus, and Antrodemus thus should be the preferred name because as the older name it had priority. ^[16] Antrodemus became the accepted name for this familiar genus for over fifty years, until James Madsen published on the Cleveland-Lloyd specimens and concluded that Allosaurus should be used because Antrodemus was based on material with poor, if any, diagnostic features and locality information (for example, the geological formation that the single bone of Antrodemus came from is unknown). ^[3] "Antrodemus" has been used informally for convenience when distinguishing between the skull Gilmore restored and the composite skull restored by Madsen. ^[40]

Cleveland-Lloyd discoveries

Although sporadic work at what became known as the Cleveland-Lloyd Dinosaur Quarry in Emery County, Utah had taken place as early as 1927, and the fossil site itself described by William J. The Cleveland Lloyd Dinosaur Quarry National Natural Landmark (designated a National Natural Landmark in 1966) is located on a gravel road about 30 miles Emery County is a County located in the US state of Utah. As of 2000 the population was 10860 and by 2005 had been estimated to decrease to 10711 The State of Utah (ˈjuːtɔː or) is a western state of the United States. Stokes in 1945,^[41] major operations did not begin there until 1960. Under a cooperative effort involving nearly 40 institutions, thousands of bones were recovered between 1960 and 1965. ^[3] The quarry is notable for the predominance of Allosaurus remains, the condition of the specimens, and the lack of scientific resolution on how it came to be. The majority of bones belong to the large theropod Allosaurus fragilis (it is estimated that the remains of at least 46 A. fragilis have been found there, out of at minimum 73 dinosaurs), and the fossils found there are disarticulated and well-mixed. Nearly a dozen scientific papers have been written on the taphonomy of the site, coming up with numerous contradictory explanations for how it formed. Taphonomy is the study of a decaying Organism over time The term taphonomy (from the Greek taphos - τάφος meaning burial and nomos - Suggestions have ranged from animals getting stuck in a bog, to becoming trapped in deep mud, to falling victim to drought-induced mortality around a waterhole, to getting trapped in a spring-fed pond or seep. A drought is an extended period of months or years when a region notes a deficiency in its water supply ^[42] Regardless of the actual cause, the great quantity of well-preserved Allosaurus remains has allowed this genus to be known in detail, making it among the best-known theropods. Skeletal remains from the quarry pertain to individuals of almost all ages and sizes, from less than 1 meter (3. 3 ft)^[43] to 12 meters (39 ft) long, and the disarticulation is an advantage for describing bones usually found fused. ^[3]

Recent work: 1980s–present

The period since Madsen's monograph has been marked by a great expansion in studies dealing with topics concerning Allosaurus in life (paleobiological and paleoecological topics). Paleobiology (sometimes spelled palaeobiology) is a growing and comparatively new discipline which combines the methods and findings of the Natural science Biology Paleoecology uses data from Fossils and subfossils to reconstruct the Ecosystems of the past Such studies have covered topics including skeletal variation,^[44] growth,^[45][46] skull construction,^[47] hunting methods,^[48] the brain,^[49] and the possibility of gregarious living and parental care. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain ^[50] Reanalysis of old material (particularly of large 'allosaur' specimens),^[6][51] new discoveries in Portugal,^[52] and several very complete new specimens^[53][13][54] have also contributed to the growing knowledge base.

"Big Al"

One of the more significant Allosaurus finds was the 1991 discovery of "Big Al" (MOR 693), a 95% complete, partially articulated specimen that measured about 8 meters (about 26 ft) in length. The Museum of the Rockies, affiliated with Montana State University in Bozeman and the Smithsonian Institution, is located in Bozeman, Montana MOR 693 was excavated near Shell, Wyoming, by a joint Museum of the Rockies and University of Wyoming Geological Museum team. Shell is an unincorporated community in Big Horn County, Wyoming, United States. The University of Wyoming is a Land-grant university located in Laramie, Wyoming, situated on Wyoming's high Laramie Plains, at an elevation ^[55] This skeleton was discovered by a Swiss team, led by Kirby Siber. The same team later excavated a second Allosaurus, "Big Al Two", which is the best preserved skeleton of its kind to date. ^[54]

The completeness, preservation, and scientific importance of this skeleton gave "Big Al" its name; the individual itself was below the average size for Allosaurus fragilis,^[55] and was a subadult estimated at only 87% grown. ^[56] The specimen was described by Breithaupt in 1996. ^[53] Nineteen of its bones were broken or showed signs of infection, which may have contributed to "Big Al"'s death. An infection is the detrimental Colonization of a host Organism by a foreign Species. Pathologic bones included five ribs, five vertebrae, and four bones of the feet; several damaged bones showed osteomyelitis, a bone infection. Pathology (from Greek grc πάθος pathos, "fate harm" and grc -λογία -logia) is the study and Osteomyelitis is an Infection of Bone or Bone marrow, usually caused by Pyogenic Bacteria or Mycobacteria. A particular problem for the living animal was infection and trauma to the right foot that probably affected movement and may have also predisposed the other foot to injury because of a change in gait. ^[56]

Species and taxonomy

Main article: Species of Allosaurus

It is unclear how many species of Allosaurus there were. There have been a number of potential Species assigned to the Carnosaurian Dinosaur Genus Allosaurus since its Seven species have been considered potentially valid since 1988 (A. amplexus,^[6] A. atrox,^[6] A. europaeus,^[57] the type species A. In Taxonomy, a type species is the species that originally defined a genus. fragilis,^[11] the as-yet not formally described "A. jimmadseni",^[5] A. maximus,^[44] and A. tendagurensis^[11]), although only a fraction are usually considered valid at any given time. Additionally, there are at least ten dubious or undescribed species that have been assigned to Allosaurus over the years, along with the species belonging to genera now sunk into Allosaurus. In the most recent review of basal tetanuran theropods, only A. Tetanurae, or "stiff tails" is a Clade that includes most theropod dinosaurs including Birds Tetanurans (or tetanurines first appear during the early fragilis (including A. amplexus and A. atrox as synonyms), "A. jimmadseni" (as an unnamed species), and A. tendagurensis were accepted as potentially valid species, with A. europaeus not yet proposed and A. maximus assigned to Saurophaganax. ^[11]

A. amplexus, A. atrox, A. fragilis, "A. jimmadseni", and A. maximus are all known from remains discovered in the Kimmeridgian–Tithonian Upper Jurassic-age Morrison Formation of the United States, spread across the states of Colorado, Montana, New Mexico, Oklahoma, South Dakota, Utah, and Wyoming. The Kimmeridgian is a stage of the Late Jurassic Epoch. It spans the time between 155 The Tithonian is the final stage of the Late Jurassic Epoch. It spans the time between 150 The Late Jurassic (or Malm) Epoch of the Jurassic Period is the unit of geologic time from 161 The United States of America —commonly referred to as the The State of Colorado ( or chiefly by nonresidents) is a state located in the Rocky Mountain region of the United States of America. Montana ( is a state in the Western United States. One-third of the state in the western part contains numerous mountain ranges (approximately 77 named of the northern New Mexico ( is a state located in the southwestern region of the United States of America. Oklahoma ( is a state located in the South Central region of the United States of America. South Dakota ( is a state located in the Midwestern region of the United States of America. A. fragilis is regarded as the most common, known from the remains of at least sixty individuals. ^[11] Debate has gone on since the 1980s regarding the possibility that there are two common Morrison Formation species of Allosaurus, with the second known as A. atrox;^[6][58] recent work has followed a "one species" interpretation,^[11] with the differences seen in the Morrison Formation material attributed to individual variation. ^[59][60] A. europaeus was found in the Kimmeridgian-age Porto Novo Member of the Lourinhã Formation,^[57] but may be the same as A. Lourinhã Formation is a Geological formation located in West Portugal, named for the municipality of Lourinhã, from which a wide array of fossils come fragilis. ^[61] A. tendagurensis was found in Kimmeridgian-age rocks of Tendaguru, in Mtwara, Tanzania. The Tendaguru beds are a fossil rich formation in Tanzania. It has been considered the richest of Late Jurassic strata in Africa. This article is about the region for the city see Mtwara (city. ^[62] Although the most recent review tentatively accepted it as a valid species of Allosaurus, it may be a more basal tetanuran,^[63] or simply a dubious theropod. In zoological nomenclature, a nomen dubium ( Latin for "doubtful name" plural nomina dubia) is a scientific name that is ^[1] Although obscure, it was a large theropod, possibly around 10 meters long (33 ft) and 2. 5 metric tons (2. 8 short tons) in weight. ^[2]

Allosaurus is regarded as a probable synonym of the genera Antrodemus, Creosaurus, Epanterias, and Labrosaurus. ^[11] Most of the species that are regarded as synonyms of A. fragilis, or that were misassigned to the genus, are obscure and were based on scrappy remains. One exception is Labrosaurus ferox, named in 1884 by Marsh for an oddly formed partial lower jaw, with a prominent gap in the tooth row at the tip of the jaw, and a rear section greatly expanded and turned down. ^[64] Later researchers suggested that the bone was pathologic, showing an injury to the living animal,^[16] and that part of the unusual form of the rear of the bone was due to plaster reconstruction. Pathology (from Greek grc πάθος pathos, "fate harm" and grc -λογία -logia) is the study and ^[65] It is now regarded as an example of A. fragilis. ^[11] Other remains thought to pertain to Allosaurus have come from across the world, including Australia,^[66] Siberia,^[67] and Switzerland,^[1] but these fossils have been reassessed as belonging to other dinosaurs. For a topic outline on this subject see List of basic Australia topics. Siberia (Сиби́рь Sibir) is the name given to the vast region constituting almost all of Northern Asia and for the most part currently serving Switzerland (English pronunciation; Schweiz Swiss German: Schwyz or Schwiiz Suisse Svizzera Svizra officially the Swiss Confederation

Paleoecology

Allosaurus was the most common large theropod in the vast tract of Western American fossil-bearing rock known as the Morrison Formation, and as such was at the top trophic level of the Morrison food web. The Western United States &mdashcommonly referred to as the American West or simply the West &mdashtraditionally refers to the region comprising the westernmost In Ecology, trophic dynamics is the system of trophic levels ( Greek trophē, food which describe the position that an organism occupies Food chains, also called food networks and/or trophic networks, describe the feeding relationships between species within an Ecosystem. ^[68] The Morrison Formation is interpreted as a semiarid environment with distinct wet and dry seasons, and flat floodplains. A Semi-arid climate or steppe climate generally describes climatic regions that receive low annual Rainfall (250-500 mm or 10-20 in A wet season or rainy season is a Season in which the average Rainfall in a region is significantly increased The dry season is a term commonly used when describing the weather in the Tropics. ||-||-||-||-||-||-||-||}A floodplain, or flood plain, is flat or nearly flat land adjacent to a Stream or River that experiences occasional or periodic ^[69] Vegetation varied from river-lining forests of conifers, tree ferns, and ferns, to fern savannas with rare trees. "Riverine" redirects here For the use of that term in Maritime geography, see there The order Cyatheales is a Taxonomic division of the Fern subclass Cyatheatae, which includes the tree ferns. A fern is any one of a group of about 20000 Species of Plants classified in the phylum or division Pteridophyta, also known as Filicophyta A savanna or savannah is a Tropical or Subtropical Grassland or Woodland Ecosystem. ^[70]

The Morrison Formation has been a rich fossil hunting ground, holding fossils of green alage, fungi, mosses, horsetails, ferns, cycads, ginkgoes, and several families of conifers. Chlorophyta, a division of Green algae, of mostly aquatic Photosynthetic Eukaryotic organisms A fungus (ˈfʌŋgəs is a eukaryotic Organism that is a member of the kingdom Fungi (ˈfʌndʒaɪ Mosses are small soft Plants that are typically 1–10  cm (0 Equisetum is a genus of Vascular plants that reproduce by spores rather than seeds Cycads are a group of Seed plants characterized by a large crown of compound leaves and a stout trunk. Ginkgo is a genus of highly unusual non-flowering plants with one extant species G Other fossils discovered include bivalves, snails, ray-finned fishes, frogs, salamanders, turtles, sphenodonts, lizards, terrestrial and aquatic crocodylomorphans, several species of pterosaur, numerous dinosaur species, and early mammals such as docodonts, multituberculates, symmetrodonts, and triconodonts. Bivalves are Molluscs belonging to the class Bivalvia. They have two-part shells and typically both valves are symmetrical along the hinge line The word snail is a Common name that can be used for almost all members of the Molluscan class Gastropoda which have coiled shells in the The Actinopterygii (the plural form of Actinopterygius) comprise the class of the ray-finned fishes. This article is about the block cipher algorithm For the ultrafast laser pulse measurement technique see Frequency-resolved optical gating. Salamander (orig from Persian: sām, "fire" and andarūn, "within" is the common name for a group of approximately 500 Species Turtles are Reptiles of the Order Testudines (all living turtles belong to the Crown group Chelonia) most of Sphenodontia is an order of lizard-like reptiles that includes only one living genus the Tuatara ( Sphenodon) Lizards are a large and widespread group of Reptiles of the order Squamata, with nearly 5000 species and ranging across all continents except The Crocodylomorpha are an important group of Archosaurs that include the Crocodilians and their extinct relatives For other meanings see Pterodactyl (disambiguation. Pterosaurs (ˈtɛrəsɔr from the Greek πτερόσαυρος pterosauros Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands Docodonta is an order of extinct proto- Mammals that lived during the mid- to late- Mesozoic era The Multituberculata (multituberculates are a major branch of mammals that survived for a long period of time but eventually became completely extinct at the end of the Symmetrodonta is a basal group of Mesozoic Mammals characterized by the triangular aspect of the molars when viewed from above and the absence of a well-developed Triconodonta (also known as Eutriconodonta) is the generic name for a group of early Mammals which were close relatives of the ancestors of all present-day mammals Such dinosaurs as the theropods Ceratosaurus, Ornitholestes, and Torvosaurus, the sauropods Apatosaurus, Brachiosaurus, Camarasaurus, and Diplodocus, and the ornithischians Camptosaurus, Dryosaurus, and Stegosaurus are known from the Morrison. Ornitholestes (meaning "bird robber" was a small Theropod Dinosaur of the late Jurassic of Western Laurasia (the area that Torvosaurus (ˌtɔrvoʊˈsɔrəs TOR-vo-SOR-us) is a Genus of giant carnivorous Dinosaur, relatively similar in appearance to Sauropoda (sɔˈrɒpədə or the sauropods (/ˈsɔroʊpɒd/ are a suborder or infraorder of the Saurischian ("lizard-hipped" Brachiosaurus (ˌbrækiəˈsɔrəs meaning "arm lizard" from the Greek brachion /βραχιων meaning "arm" and sauros Camarasaurus (ˌkæmərəˈsɔrəs KAM-uh-ruh-SAWR-us meaning 'chambered lizard' referring to the holes in its Vertebrae ( Greek καμαρα Diplodocus (dɪˈplɒdəkəs /daɪˈplɒdəkəs/ Diplodocus is among the most easily identifiable dinosaurs with its classic dinosaur shape long neck Ornithischia (ɔrnɪˈθɪskiə) or Predentata is an extinct order of beaked herbivorous Dinosaurs The name ornithischia Camptosaurus (ˌkæmptəˈsɔrəs KAMP-to-SAWR-us is a Genus of plant-eating beaked Dinosaurs of the Late Jurassic and Early Cretaceous Dryosaurus (ˌdraɪoʊˈsɔrəs DRY-oh-SAWR-us meaning 'oak lizard' due to the vague oak shape of its cheek teeth ( Greek δρυο/dryo Stegosaurus (ˌstɛgəˈsɔrəs is a Genus of stegosaurid armoured Dinosaur from the Late Jurassic period ( ^[71] The Late Jurassic formations of Portugal where Allosaurus is present are interpreted as having been similar to the Morrison but with a stronger marine influence. An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. Many of the dinosaurs of the Morrison Formation are the same genera as those seen in Portuguese rocks (mainly Allosaurus, Ceratosaurus, Torvosaurus, and Apatosaurus), or have a close counterpart (Brachiosaurus and Lusotitan, Camptosaurus and Draconyx). Lusotitan is the name given to a genus of Dinosaur from the Late Jurassic Period. Draconyx (meaning "dragon claw" is a Genus of Dinosaur from the Late Jurassic. ^[72]

Allosaurus coexisted with fellow large theropods Ceratosaurus and Torvosaurus in both the United States and Portugal. ^[72] The three appear to have had different ecological niches, based on anatomy and the location of fossils. In Ecology, a niche (pronounced nich nēsh or nish A shorthand definition of niche is how an organism makes a living Ceratosaurs and torvosaurs may have preferred to be active around waterways, and had lower, thinner bodies that would have given them an advantage in forest and underbrush terrains, whereas allosaurs were more compact, with longer legs, faster but less maneuverable, and seem to have preferred dry floodplains. ^[73] Ceratosaurus, better known than Torvosaurus, differed noticeably from Allosaurus in functional terms by having a taller, narrower skull with large, broad teeth. ^[40] Allosaurus was itself a potential food item to other carnivores, as illustrated by an Allosaurus pubic foot marked by the teeth of another theropod, probably Ceratosaurus or Torvosaurus. For the bone in many mammals often called the penis bone see Baculum The android pubic bone is the Ventral and Anterior The location of the bone in the body (along the bottom margin of the torso and partially shielded by the legs), and the fact that it was among the most massive in the skeleton, indicates that the Allosaurus was being scavenged. ^[74]

Paleobiology

Life history

The wealth of Allosaurus fossils, from nearly all ages of individuals, allows scientists to study how the animal grew and how long its lifespan may have been. Remains may reach as far back in the lifespan as eggs—crushed eggs from Colorado have been suggested as those of Allosaurus. In most Birds and Reptiles an egg ( Latin ovum) is the Zygote, resulting from Fertilization of the Ovum. ^[1] Based on histological analysis of limb bones, the upper age limit for Allosaurus is estimated at 22 to 28 years, which is comparable to that of other large theropods like Tyrannosaurus. Histology (from the Greek = 'tissue' is the study of the microscopic anatomy of cells and tissues of Plants and Tyrannosaurus ( or, meaning 'tyrant lizard' is a Genus of Theropod Dinosaur. From the same analysis, its maximum growth appears to have been at age 15, with an estimated growth rate of about 150 kilograms (330 lb) per year. The pound or pound-mass (abbreviation lb, lbm, or sometimes in the United States #) is a unit of Mass ^[45]

Medullary bone tissue, also found in dinosaurs as diverse as Tyrannosaurus and Tenontosaurus, has been found in at least one Allosaurus specimen, a shin bone from the Cleveland-Lloyd Quarry. Tyrannosaurus ( or, meaning 'tyrant lizard' is a Genus of Theropod Dinosaur. Tenontosaurus (tɨˌnɒntəˈsɔrəs ten-ON-toe-SORE-us is a Genus of medium- to large-sized Ornithopod Dinosaur. The tibia, shinbone, or shankbone is the larger and stronger of the two Bones in the Leg below the Knee in vertebrates and connects Today, this bone tissue is only formed in female birds that are laying eggs, as it is used to supply calcium to shells. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Its presence in the Allosaurus individual establishes sex and shows she had reached reproductive age. By counting growth lines, it was shown that she was 10 years old at death, so sexual maturity in Allosaurus was attained well before maximum growth and size. ^[75]

The discovery of a juvenile specimen with a nearly complete hindlimb shows that the legs were relatively longer in juveniles, and the lower segments of the leg (shin and foot) were relatively longer than the thigh. These differences suggest that younger Allosaurus were faster and had different hunting strategies than adults, perhaps chasing small prey as juveniles, then becoming ambush hunters of large prey upon adulthood. ^[46] The thigh bone became thicker and wider during growth, and the cross-section less circular, as muscle attachments shifted, muscles became shorter, and the growth of the leg slowed. These changes imply that juvenile legs has less predictable stresses compared with adults, which would have moved with more regular forward progression. ^[76]

Feeding

Paleontologists accept Allosaurus as an active predator of large animals. Sauropods seem to be likely candidates as both live prey and as objects of scavenging, based on the presence of scrapings on sauropod bones fitting allosaur teeth well and the presence of shed allosaur teeth with sauropod bones. Sauropoda (sɔˈrɒpədə or the sauropods (/ˈsɔroʊpɒd/ are a suborder or infraorder of the Saurischian ("lizard-hipped" ^[77] There is dramatic evidence for allosaur attacks on Stegosaurus, including an Allosaurus tail vertebra with a partially healed puncture wound that fits a Stegosaurus tail spike, and a Stegosaurus neck plate with a U-shaped wound that correlates well with an Allosaurus snout. The thagomizer, or tail spikes, is an arrangement of four to ten spikes on the tails of particular Dinosaurs of the clade Stegosauria, of ^[78] However, as Gregory Paul noted in 1988, Allosaurus was probably not a predator of fully grown sauropods, unless it hunted in packs, as it had a modestly sized skull and relatively small teeth, and was greatly outweighed by contemporaneous sauropods. ^[6] Another possibility is that it preferred to hunt juveniles instead of fully grown adults. ^[58] Research in the 1990s and 2000s may have found other solutions to this question. Robert T. Bakker, comparing Allosaurus to Tertiary sabre-toothed carnivorous mammals, found similar adaptations, such as a reduction of jaw muscles and increase in neck muscles, and the ability to open the jaws extremely wide. Robert T Bakker (born March 24, 1945, in Bergen County New Jersey) is an American Paleontologist who helped reshape modern theories about The chuprichondira geological time interval covers roughly the time span between the demise of the non- avian Dinosaurs and beginning of the most recent Ice Age, approximately Although Allosaurus did not have sabre teeth, Bakker suggested another mode of attack that would have used such neck and jaw adaptations: the short teeth in effect became small serrations on a saw-like cutting edge running the length of the upper jaw, which would have been driven into prey. A saw is a Tool that uses a hard blade or wire with an abrasive edge to cut through softer materials This type of jaw would permit slashing attacks against much larger prey, with the goal of weakening the victim. ^[48]

Similar conclusions were drawn by another study using finite element analysis on an Allosaurus skull. According to their biomechanical analysis, the skull was very strong but had a relatively small bite force. By using jaw muscles only, it could produce a bite force of 805 to 2,148 N, less than the values for alligators (13,000 N), lions (4,167 N), and leopards (2,268 N), but the skull could withstand nearly 55,500 N of vertical force against the tooth row. The newton (symbol N) is the SI derived unit of Force, named after Isaac Newton in recognition of his work on Classical for differences between alligators and crocodiles please see Crocodilia An Alligator is a Crocodilian in the Genus The lion ( Panthera leo) is a member of the family Felidae and one of four Big cats in the Genus Panthera. The leopard (lɛpɚd Panthera pardus) is an Old World Mammal of the Felidae family and the smallest of the four roaring The authors suggested that Allosaurus used its skull like a hatchet against prey, attacking open-mouthed, slashing flesh with its teeth, and tearing it away without splintering bones, unlike Tyrannosaurus, which is thought to have been capable of damaging bones. They also suggested that the architecture of the skull could have permitted the use of different strategies against different prey; the skull was light enough to allow attacks on smaller and more agile ornithopods, but strong enough for high-impact ambush attacks against larger prey like stegosaurids and sauropods. ^[47] Their interpretations were challenged by other researchers, who found no modern analogues to a hatchet attack and considered it more likely that the skull was strong to compensate for its open construction when absorbing the stresses from struggling prey. ^[79] The original authors noted that Allosaurus itself has no modern equivalent, that the tooth row is well-suited to such an attack, and that articulations in the skull cited by their detractors as problematic actually helped protect the palate and lessen stress. The palate (ˈpælɨt is the roof of the Mouth in humans and Vertebrate animals ^[80] Another possibility for handling large prey is that theropods like Allosaurus were "flesh grazers" which could take bites of flesh out of living sauropods that were sufficient to sustain the predator so it would not have needed to expend the effort to kill the prey outright. This strategy would also potentially have allowed the prey to recover and be fed upon in a similar way later. ^[11]

Other aspects of feeding include the eyes, arms, and legs. The shape of the skull of Allosaurus limited potential binocular vision to 20° of width, slightly less than that of modern crocodilians. Binocular vision is vision in which both Eyes are used together Crocodilia is an order of large Reptiles that appeared about 84 million years ago in the late Cretaceous Period ( Campanian stage As with crocodilians, this may have been enough to judge prey distance and time attacks. ^[81] The arms, compared with those of other theropods, were suited for both grasping prey at a distance or clutching it close,^[17] and the articulation of the claws suggests that they could have been used to hook things. ^[16] Finally, the top speed of Allosaurus has been estimated at 30 to 55 kilometers per hour (19 to 34 miles per hour). ^[82]

Social behavior

Allosaurus has long been regarded in the semitechnical and popular literature as an animal that preyed on sauropods and other large dinosaurs by hunting in groups. ^[25][8][58] Robert T. Bakker has extended social behavior to parental care, and has interpreted shed allosaur teeth and chewed bones of large prey animals as evidence that adult allosaurs brought food to lairs for their young to eat until they were grown, and prevented other carnivores from scavenging on the food. A lair is a underground or other enclosed place that Animals use to hide themselves while at Sleep, Hibernation or when they take part in Reproduction ^[50] However, there is actually little evidence of gregarious behavior in theropods,^[11] and social interactions with members of the same species would have included antagonistic encounters, as shown by injuries to gastralia^[13] and bite wounds to skulls (the pathologic lower jaw named Labrosaurus ferox is one such possible example). Such head-biting may have been a way to establish dominance in a pack or to settle territorial disputes. A pack hunter is a Predator belonging to the Animal kingdom which has evolved to hunt its Prey by working together with other members of its Species In Ethology, Sociobiology and Behavioral ecology, the term territory refers to any sociographical area that an Animal of a particular Species ^[83]

Recent research suggests that Allosaurus and other theropods were like other diapsids and had largely aggressive instead of cooperative interactions with other members of their own species. Diapsids ("two arches" are a group of Reptiles that developed two holes ( Temporal fenestra) in each side of their Skulls about 300 Million One study noted cooperative hunting of prey much larger than an individual predator, as is commonly inferred for theropod dinosaurs, is rare among vertebrates in general, and modern diapsids (including lizards, crocodiles, and birds) very rarely cooperate to hunt in such a way. Vertebrates are members of the Subphylum Vertebrata, Chordates with backbones or spinal columns The grouping sometimes includes Diapsids ("two arches" are a group of Reptiles that developed two holes ( Temporal fenestra) in each side of their Skulls about 300 Million Many modern diapsid predators are territorial and will kill and cannibalize intruders of the same species, and will also do the same to smaller individuals that attempt to eat before them when aggregated at feeding sites. Cannibalism is the act of one individual of a species consuming all or part of another individual of the same species as food This suggests that, for example, the Cleveland-Lloyd quarry shows Allosaurus individuals were drawn together to feed on other disabled or dead allosaurs, and sometimes were killed in the process, thus accumulating. This could explain the high proportion of juvenile and subadult allosaurs present, as juveniles and subadults are disproportionally killed at modern group feeding sites of animals like crocodiles and komodo dragons. A crocodile is any Species belonging to the family Crocodylidae (sometimes classified instead as the Subfamily Crocodylinae) The Komodo dragon ( Varanus komodoensis) is a species of Lizard that inhabits the islands of Komodo, Rinca, Flores, Gili The same interpretation applies to Bakker's lair sites. ^[84] There is some evidence for cannibalism in Allosaurus, including Allosaurus shed teeth found among rib fragments, possible tooth marks on a shoulder blade,^[85] and cannibalized allosaur skeletons among the bones at Bakker's lair sites. In Anatomy, the scapula, omo, or shoulder blade, is the Bone that connects the Humerus (arm bone with the Clavicle (collar ^[73]

Brain and senses

The brain of Allosaurus, as interpreted from spiral CT scanning of an endocast, was more consistent with crocodilian brains than those of the other living archosaurs, birds. Computed tomography (CT is a Medical imaging method employing Tomography. An endocast or endocranial cast is a cast made of the mold formed by the impression the Brain makes on the inside of the Neurocranium (braincase providing Crocodilia is an order of large Reptiles that appeared about 84 million years ago in the late Cretaceous Period ( Campanian stage Archosaurs ( Greek for 'ruling lizards' are a group of Diapsid Reptiles represented by Modern birds and Crocodilians This group also The structure of the vestibular apparatus indicates that the skull was held nearly horizontal, as opposed to strongly tipped up or down. The vestibular system, which is a contributor to our balance system and our sense of spatial orientation is the sensory system that provides the dominant input about movement and The structure of the inner ear was like that of a crocodilian, and so Allosaurus probably could have heard lower frequencies best, and would have had trouble with subtle sounds. The inner Ear is the bony labyrinth, a system of passages comprising two main functional parts the organ of hearing or Cochlea The olfactory bulbs were large and seem to have been well suited for detecting odors, although the area for evaluating smells was relatively small. The olfactory bulb is a structure of the Vertebrate Forebrain involved in Olfaction, the perception of Odors. ^[49]

In popular culture

Along with Tyrannosaurus, Allosaurus has come to represent the quintessential large, carnivorous dinosaur in popular culture. It is a common dinosaur in museums, due in particular to the excavations at the Cleveland Lloyd Dinosaur Quarry; by 1976, as a result of cooperative operations, 38 museums in eight countries on three continents had Cleveland-Lloyd allosaur material or casts. ^[3] Allosaurus is the official state fossil of Utah. Most American states have made a state fossil designation in many cases during the 1980s. ^[86]

Allosaurus has been depicted in popular culture since the early years of the 20th century. It is top predator in both Arthur Conan Doyle's 1912 novel, The Lost World, and the 1925 film adaptation, the first full-length motion picture to feature dinosaurs (it is not to be confused with Tyrannosaurus, which also appears in the film). Sir Arthur Ignatius Conan Doyle, DL (22 May 1859 – 7 July 1930 was an Anglo-Scottish Author most noted for his stories about the The Lost World is a novel released in 1912 by Arthur Conan Doyle concerning an expedition to a Plateau in South America where prehistoric The Lost World is a 1925 Silent film adaptation of Arthur Conan Doyle 's book of the same name. ^[87] It later became the starring dinosaur of the 1956 film The Beast of Hollow Mountain,^[26] and the 1969 film The Valley of Gwangi, two genre combinations of living dinosaurs with Westerns. The Beast of Hollow Mountain is a 1956 scifi/horror western about an American Cowboy living in Mexico who discovers The Valley of Gwangi is a 1969 Fantasy film directed by Jim O'Connolly and written by William Bast. A genre (ˈʒɑːnrə also /ˈdʒɑːnrə/ from French "kind" or "sort" from Latin: genus (stem gener-) is a loose set The Western is a fiction Genre seen in Film, Television, Radio, Literature, Painting and other Visual arts. In The Valley of Gwangi, Gwangi is billed as an Allosaurus, although Ray Harryhausen based his model for the creature on Charles R. Ray Harryhausen (born Raymond Frederick Harryhausen on June 29, 1920 in Los Angeles California) is an Academy Award -winning Knight's depiction of a Tyrannosaurus. Harryhausen sometimes confuses the two, stating in a DVD interview "They're both meat eaters, they're both tyrants. . . one was just a bit larger than the other. " ^[88] In nonfictional presentations, Allosaurus appears in the second and fifth episodes of the BBC television series Walking with Dinosaurs, and the Walking with Dinosaurs special The Ballad of Big Al chronicles the life of the Allosaurus specimen nicknamed "Big Al". Walking with Dinosaurs was a six-part Television series produced by the BBC, narrated by Kenneth Branagh, and first aired in the UK The Ballad of Big Al (distributed as Allosaurus a Walking with Dinosaurs Special) is a combination biography-sequel for Walking with Dinosaurs

References

External links

• Allosaurus, the story of "Big Al", from the University of Wyoming Geological Museum in Laramie.
• Specimens, discussion, and references pertaining to Allosaurus at The Theropod Database.
• Allosaurus at DinoData.
• Public Pioneer, Utah State Fossil, Allosaurus, from Utah. gov.
• Restoration of MOR 693 ("Big Al") and and muscle and organ restoration at Scott Hartman's Skeletal Drawing website.
• List of the many possible Allosaurus species...

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