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Acrocanthosaurus atokensis
Topic Started: Jan 7 2012, 12:20 AM (8,558 Views)
DinosaurMichael
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Acrocanthosaurus atokensis

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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: †Carcharodontosauridae
Genus: †Acrocanthosaurus

Fossil range: Early Cretaceous, 116–110 Ma

Acrocanthosaurus ( /ˌækrɵˌkænθɵˈsɔrəs/ ak-rə-kan-thə-sor-əs; meaning "high-spined lizard") is a genus of theropod dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. Its fossil remains are found mainly in the U.S. states of Oklahoma, Texas, and Arkansas, although teeth attributed to Acrocanthosaurus have been found as far east as Maryland.

Acrocanthosaurus was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back and hips. Acrocanthosaurus was one of the largest theropods, approaching 12 meters (40 ft) in length, and weighing up to 6–7 metric tons (6.5–7.5 short tons). Large theropod footprints discovered in Texas may have been made by Acrocanthosaurus, although there is no direct association with skeletal remains.

Recent discoveries have elucidated many details of its anatomy, allowing for specialized studies focusing on its brain structure and forelimb function. Acrocanthosaurus was the largest theropod in its ecosystem and likely an apex predator which possibly preyed on large sauropods and ornithopods.

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Description
Although slightly smaller than colossal relatives like Giganotosaurus, Acrocanthosaurus was still among the largest theropods ever to exist. The longest known individual measured 11.5 meters (38 ft) from snout to tail tip and weighed an estimated 6,000–7,000 kilograms (13,000–15,000 lb). Its skull alone was nearly 1.3 meters (4.3 ft) in length.

The skull of Acrocanthosaurus, like most other allosauroids, was long, low and narrow. The weight-reducing opening in front of the eye socket (antorbital fenestra) was quite large, more than a quarter of the length of the skull and two-thirds of its height. The outside surface of the maxilla (upper jaw bone) and the upper surface of the nasal bone on the roof of the snout were not nearly as rough-textured as those of Giganotosaurus or Carcharodontosaurus. Long, low ridges arose from the nasal bones, running along each side of the snout from the nostril back to the eye, where they continued onto the lacrimal bones. This is a characteristic feature of all allosauroids. Unlike Allosaurus, there was no prominent crest on the lacrimal bone in front of the eye. The lacrimal and postorbital bones met to form a thick brow over the eye, as seen in carcharodontosaurids and the unrelated abelisaurids. Nineteen curved, serrated teeth lined each side of the upper jaw, but a tooth count for the lower jaw has not been published. Acrocanthosaurus teeth were wider than those of Carcharodontosaurus and did not have the wrinkled texture that characterized the carcharodontosaurids. The dentary (tooth-bearing lower jaw bone) was squared off at the front edge, as in Giganotosaurus, and shallow, while the rest of the jaw behind it became very deep. Acrocanthosaurus and Giganotosaurus shared a thick horizontal ridge on the outside surface of the surangular bone of the lower jaw, underneath the articulation with the skull.

The most notable feature of Acrocanthosaurus was its row of tall neural spines, located on the vertebrae of the neck, back, hips and upper tail, which could be more than 2.5 times the height of the vertebrae from which they extended. Other dinosaurs also had high spines on the back, sometimes much higher than those of Acrocanthosaurus. For instance, the unrelated Spinosaurus had spines nearly 2 meters (6.5 ft) tall, about 11 times taller than the bodies of its vertebrae. Rather than supporting a skin 'sail' as seen in Spinosaurus, the lower spines of Acrocanthosaurus had attachments for powerful muscles like those of modern bison, probably forming a tall, thick ridge down its back. The function of the spines remains unknown, although they may have been involved in communication, fat storage, or temperature control. All of its cervical (neck) and dorsal (back) vertebrae had prominent depressions (pleurocoels) on the sides, while the caudal (tail) vertebrae bore smaller ones. This is more similar to carcharodontosaurids than to Allosaurus.

Aside from its vertebrae, Acrocanthosaurus had a typical allosauroid skeleton. Acrocanthosaurus was bipedal, with a long, heavy tail counterbalancing the head and body, maintaining its center of gravity over its hips. Its forelimbs were relatively shorter and more robust than those of Allosaurus but were otherwise similar: each hand bore three clawed digits. Unlike many smaller fast-running dinosaurs, its femur was longer than its tibia and metatarsals, suggesting that Acrocanthosaurus was not a fast runner. Unsurprisingly, the hind leg bones of Acrocanthosaurus were proportionally more robust than its smaller relative Allosaurus. Its feet had four digits each, although as is typical for theropods, the first was much smaller than the rest and did not make contact with the ground.

Classification and systematics
Acrocanthosaurus is classified in the superfamily Allosauroidea within the infraorder Tetanurae. This superfamily is characterized by paired ridges on the nasal and lacrimal bones on top of the snout and tall neural spines on the neck vertebrae, among other features. It was originally placed in the family Allosauridae with Allosaurus,[4] an arrangement also supported by studies as late as 2000. Most studies have found it to be a member of the related family Carcharodontosauridae.

At the time of its discovery, Acrocanthosaurus and most other large theropods were known from only fragmentary remains, leading to highly variable classifications for this genus. J. Willis Stovall and Wann Langston, Jr. first assigned it to the "Antrodemidae," the equivalent of Allosauridae, but it was transferred to the taxonomic wastebasket Megalosauridae by Alfred Sherwood Romer in 1956. To other authors, the long spines on its vertebrae suggested a relationship with Spinosaurus. This interpretation of Acrocanthosaurus as a spinosaurid persisted into the 1980s, and was repeated in the semi-technical dinosaur books of the time.

Tall spined vertebrae from the Early Cretaceous of England were once considered to be very similar to those of Acrocanthosaurus, and in 1988 Gregory S. Paul named them as a second species of the genus, A. altispinax. These bones were originally assigned to Altispinax, an English theropod otherwise known only from teeth, and this assignment led to at least one author proposing that Altispinax itself was a synonym of Acrocanthosaurus. These vertebrae were later assigned to the new genus Becklespinax, separate from both Acrocanthosaurus and Altispinax.

Most cladistic analyses including Acrocanthosaurus have found it to be a carcharodontosaurid, usually in a basal position relative to the African Carcharodontosaurus and Giganotosaurus from South America. It has often been considered the sister taxon to the equally-basal Eocarcharia, also from Africa. Neovenator, discovered in England, is often considered an even more basal carcharodontosaurid, or as a basal member of a sister group called Neovenatoridae. This suggests that the family originated in Europe and then dispersed into the southern continents (at the time united as the supercontinent Gondwana). If Acrocanthosaurus was a carcharodontosaurid, then dispersal would also have occurred into North America.[6] All known carcharodontosaurids lived during the early-to-middle Cretaceous Period.

Discovery and naming
Acrocanthosaurus is named for its tall neural spines, from the Greek ɑκρɑ/akra ('high'), ɑκɑνθɑ/akantha ('thorn' or 'spine') and σɑʊρος/sauros ('lizard'). There is one named species (A. atokensis), which is named after Atoka County in Oklahoma, where the original specimens were found. The name was coined in 1950 by American paleontologists J. Willis Stovall and Wann Langston, Jr. Langston had proposed the name "Acracanthus atokaensis" for the genus and species in his unpublished 1947 master's thesis, but the name was changed to Acrocanthosaurus atokensis for formal publication.

Skull of NCSM 14345, North Carolina Museum of Natural SciencesThe holotype and paratype (OMNH 10146 and OMNH 10147), described at the same time in 1950, consist of two partial skeletons and a piece of skull material from the Antlers Formation in Oklahoma.[4] Two much more complete specimens were described in the 1990s. The first (SMU 74646) is a partial skeleton, missing most of the skull, recovered from the Twin Mountains Formation of Texas and currently part of the Fort Worth Museum of Science and History collection.[6] An even more complete skeleton (NCSM 14345, nicknamed 'Fran') was recovered from the Antlers Formation of Oklahoma by Cephis Hall and Sid Love, prepared by the Black Hills Institute in South Dakota, and is now housed at the North Carolina Museum of Natural Sciences in Raleigh. This specimen is the largest and includes the only known complete skull and forelimb. Skeletal elements of OMNH 10147 are almost the same size as comparable bones in NCSM 14345, indicating an animal of roughly the same size, while the holotype and SMU 74646 are significantly smaller.

Acrocanthosaurus may be known from less complete remains outside of Oklahoma and Texas. A tooth from southern Arizona has been referred to the genus, and matching tooth marks have been found in sauropod bones from the same area. Several teeth from the Arundel Formation of Maryland have been described as almost identical to those of Acrocanthosaurus and may represent an eastern representative of the genus. Many other teeth and bones from various geologic formations throughout the western United States have also been referred to Acrocanthosaurus, but most of these have been misidentified.

Paleobiology

Forelimb function
Like those of most other non-avian theropods, Acrocanthosaurus forelimbs did not make contact with the ground and were not used for locomotion; instead they served a predatory function. The discovery of a complete forelimb (NCSM 14345) allowed the first analysis of the function and range of motion of the forelimb in Acrocanthosaurus. The study examined the bone surfaces which would have articulated with other bones to determine how far the joints could move without dislocating. In many of the joints, the bones did not fit together exactly, indicating the presence of a considerable amount of cartilage in the joints, as is seen in many living archosaurs. Among other findings, the study suggested that, in a resting position, the forelimbs would have hung from the shoulders with the humerus angled backwards slightly, the elbow bent, and the claws facing medially (inwards).

The shoulder of Acrocanthosaurus was limited in its range of motion compared to that of humans. The arm could not swing in a complete circle, but could retract (swing backwards) 109° from the vertical, so that the humerus could actually be angled slightly upwards. Protraction (swinging forwards) was limited to only 24° past the vertical. The arm was unable to reach a vertical position when adducting (swinging downwards), but could abduct (swing upwards) to 9° above horizontal. Movement at the elbow was also limited compared to humans, with a total range of motion of only 57°. The arm could not completely extend (straighten), nor could it flex (bend) very far, with the humerus unable even to form a right angle with the forearm. The radius and ulna (forearm bones) locked together so that there was no possibility of pronation or supination (twisting) as in human forearms.

None of the carpals (wrist bones) fit together precisely, suggesting the presence of a large amount of cartilage in the wrist, which would have stiffened it. All of the digits were able to hyperextend (bend backwards) until they nearly touched the wrist. When flexed, the middle digit would converge towards the first digit, while the third digit would twist inwards. The first digit of the hand bore the largest claw, which was permanently flexed so that it curved back towards the underside of the hand. Likewise, the middle claw may have been permanently flexed, while the third claw, also the smallest, was able to both flex and extend.

After determining the ranges of motion in the joints of the forelimb, the study went on to hypothesize about the predatory habits of Acrocanthosaurus. The forelimbs could not swing forward very far, unable even to scratch the animal's own neck. Therefore they were not likely to have been used in the initial capture of prey and Acrocanthosaurus probably led with its mouth when hunting. On the other hand, the forelimbs were able to retract towards the body very strongly. Once prey had been seized in the jaws, the heavily muscled forelimbs may have retracted, holding the prey tightly against the body and preventing escape. As the prey animal attempted to pull away, it would only have been further impaled on the permanently flexed claws of the first two digits. The extreme hyperextensibility of the digits may have been an adaptation allowing Acrocanthosaurus to hold struggling prey without fear of dislocation. Once the prey was trapped against the body, Acrocanthosaurus may have dispatched it with its jaws. Another possibility is that Acrocanthosaurus held its prey in its jaws, while repeatedly retracting its forelimbs, tearing large gashes with its claws.

Brain and inner ear structure
In 2005, scientists reconstructed an endocast (replica) of an Acrocanthosaurus cranial cavity using computed tomography (CT scanning) to analyze the spaces within the holotype braincase (OMNH 10146). In life, much of this space would have been filled with the meninges and cerebrospinal fluid, in addition to the brain itself. However, the general features of the brain and cranial nerves could be determined from the endocast and compared to other theropods for which endocasts have been created. While the brain is similar to many theropods, it is most similar to that of allosauroids. It most resembles the brains of Carcharodontosaurus and Giganotosaurus rather than those of Allosaurus or Sinraptor, providing support for the hypothesis that Acrocanthosaurus was a carcharodontosaurid.

The brain was slightly sigmoidal (S-shaped), without much expansion of the cerebral hemispheres, more like a crocodile than a bird. This is in keeping with the overall conservatism of non-coelurosaurian theropod brains. Acrocanthosaurus had large and bulbous olfactory bulbs, indicating a good sense of smell. Reconstructing the semicircular canals of the ear, which control balance, shows that the head was held at a 25° angle below horizontal. This was determined by orienting the endocast so that the lateral semicircular canal was parallel to the ground, as it usually is when an animal is in an alert posture.

Possible footprints
The Glen Rose Formation of central Texas preserves many dinosaur footprints, including large, three-toed theropod prints. The most famous of these trackways was discovered along the Paluxy River in Dinosaur Valley State Park, a section of which is now on exhibit in the American Museum of Natural History in New York, although several other sites around the state have been described in the literature. It is impossible to say what animal made the prints, since no fossil bones have been associated with the trackways. However, scientists have long considered it likely that the footprints belong to Acrocanthosaurus. A 2001 study compared the Glen Rose footprints to the feet of various large theropods but could not confidently assign them to any particular genus. However, the study noted that the tracks were within the ranges of size and shape expected for Acrocanthosaurus. Because the Glen Rose Formation is close to the Antlers and Twin Mountains Formations in both geographical location and geological age, and the only large theropod known from those formations is Acrocanthosaurus, the study concluded that Acrocanthosaurus was most likely to have made the tracks.

The famous Glen Rose trackway on display in New York includes theropod footprints belonging to several individuals which moved in the same direction as up to twelve sauropod dinosaurs. The theropod prints are sometimes found on top of the sauropod footprints, indicating that they were formed later. This has been put forth as evidence that a small pack of Acrocanthosaurus was stalking a herd of sauropods. While interesting and plausible, this hypothesis is difficult to prove and other explanations exist. For example, several solitary theropods may have moved through in the same direction at different times after the sauropods had passed, creating the appearance of a pack stalking its prey. The same can be said for the purported "herd" of sauropods, who also may or may not have been moving as a group. At a point where it crosses the path of one of the sauropods, one of the theropod trackways is missing a footprint, which has been cited as evidence of an attack. However, other scientists doubt the validity of this interpretation because the sauropod did not change gait, as would be expected if a large predator were hanging onto its side.

Pathology
The skull of the Acrocanthosaurus atokensis holotype shows light exostotic material on the squamosal. The neural spine of the eleventh vertebra was fractured and healed while the neural spine of its third tail vertebra had an unusual hook-like structure.

Paleoecology
Definite Acrocanthosaurus fossils have been found in the Twin Mountains Formation of northern Texas and the Antlers Formation of southern Oklahoma. These geological formations have not been dated radiometrically, but scientists have used biostratigraphy to estimate their age. Based on changes in ammonite taxa, the boundary between the Aptian and Albian stages of the Early Cretaceous has been located within the Glen Rose Formation of Texas, which may contain Acrocanthosaurus footprints and lies just above the Twin Mountains Formation. This indicates that the Twin Mountains Formation lies entirely within the Aptian stage, which lasted from 125 to 112 million years ago. The Antlers Formation contains fossils of Deinonychus and Tenontosaurus, two dinosaur genera also found in the Cloverly Formation of Montana, which has been radiometrically dated to the Aptian and Albian stages, suggesting a similar age for the Antlers. Therefore Acrocanthosaurus most likely existed between 125 and 100 million years ago.

During this time, the area preserved in the Twin Mountains and Antlers formations was a large floodplain that drained into a shallow inland sea. A few million years later, this sea would expand to the north, becoming the Western Interior Seaway and dividing North America in two for nearly the entire Late Cretaceous. The Glen Rose Formation represents a coastal environment, with possible Acrocanthosaurus tracks preserved in mudflats along the ancient shoreline. As Acrocanthosaurus was a large predator, it is expected that it had an extensive home range and lived in many different environments in the area. Potential prey animals include sauropods like Paluxysaurus or possibly even the enormous Sauroposeidon, as well as large ornithopods like Tenontosaurus. The smaller theropod Deinonychus also prowled the area but at 3 meters (10 ft) in length, most likely provided only minimal competition for Acrocanthosaurus.

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Edited by Taipan, Jan 16 2012, 01:51 PM.
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This is from our old forum.  :'(
Edited by Wolf Eagle, Jan 7 2012, 09:39 AM.
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Dasyurus
 


Description
Although slightly smaller than gigantic relatives like Giganotosaurus, Acrocanthosaurus was still among the largest theropods ever to exist. The longest known individual measured 11.5 meters (38 ft) from snout to tail tip and weighed an estimated 2400 kilograms (5300 lb). Its skull alone was nearly 1.3 meters (4.3 ft) in length.



Updated weight estimate :

taipan
 
How Fat or Fit Were Dinosaurs? Scientists Use Laser Imaging

ScienceDaily (Feb. 20, 2009) — Karl Bates and his colleagues in the palaeontology and biomechanics research group have reconstructed the bodies of five dinosaurs, two T. rex (Stan at the Manchester Museum and the Museum of the Rockies cast MOR555), an Acrocanthosaurus atokensis, a Strutiomimum sedens and an Edmontosaurus annectens.

The team found that the smaller Museum of the Rockies T. rex could have weighed anywhere between 5.5 and 7 tonnes, while the larger specimen (Stan) might have weighed as much as 8 tonnes.

Acrocanthosaurus atokensis was a large predatory dinosaur that looked like T. rex but with large spines on its back and roamed the earth much earlier in the mid Cretaceous period, around 110M years ago. The team suggest Acrocanthosaurus probably weighed in at a similar mass to MOR555 and other medium sized adult T. rex at about 6 tonnes.

The Strutiomimum sedens, whose name means “ostrich mimic”, lived alongside T. rex in the late Cretaceous period and probably weighed somewhere between 0.4 – 0.6 tonnes

The reconstruction of Edmontosaurus annectens, a plant-eating hadrosaur was based on a juvenile specimen, but still weighed in at between 0.8 – 0.95 tonnes. As adults, some hadrosaurs grew as big as T. Rex, again living in the late Cretaceous period.

The team used laser scanning (LiDAR) and computer modelling methods to create a range of 3D models of the specimens, attempting to reconstruct their body sizes and shape as in life. The laser scanner images the full mounted skeleton, resulting in a detailed 3D model in which each bone retains its spatial position and articulation. This provides a high resolution skeletal framework around which the body cavity and internal organs such as stomach, lungs and air sacs can be reconstructed. This has allowed calculation of body segment masses, centres of mass and moments of inertia for each animal – all the information that is needed to analyse body movements.

Having created their ‘best-guess’ reconstruction of each animal, they then varied the volumes of body segments and respiratory organs to find the maximum plausible range of mass for the animals. Even scientists cannot be sure exactly how fat or thin animals like T. rex were in life, and the team were interested in exactly how broad the range of possible values were for body mass. They believe that the lower weight estimates are most likely to be correct as there is no good reason for the dinosaurs to weigh more than they need to as this would affect their speed, energy use and demands on the respiratory system.

The team also measured the body mass of an ostrich, as an existing subject that would show how accurate their technique was, and found the results to be correct.

They will now use the results to further investigate the locomotion of dinosaurs, specifically how they ran.

Karl said: “Our technique allows people to see and decide for themselves how fat or thin the dinosaurs might have been in life. You can see the skeleton with a belly. Anyone from a five-year-old to a Professor can see it and say, ‘I think this reconstruction is too fat or too thin’.

He added: “This study will help us in our research on how dinosaurs ran in 3-D rather than 2-D as in previous studies.

“Reconstructing more dinosaurs in such detail will allow us to examine changes in body mass and particularly centre of mass as they evolved. As we know, dinosaurs evolved into birds. As they did so, the centre of mass moved forward and different walking styles evolved. Although the dinosaurs we have reconstructed are not very close relatives of the birds, we can nevertheless see a small forwards movement in the position of the centre of mass from Acrocanthosaurus atokensis to the T. rex, which lies closer to modern birds on the evolutionary lines.”

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Best estimate reconstruction of Tyrannosaurus rex BHI 3033 in (A) right lateral, (B) dorsal, (C) cranial and (D) oblique right craniolateral views (not to scale).

http://www.sciencedaily.com/releases/2009/02/090220110912.htm
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Acrocanthosaurus Weight estimation

By Jeremy Hsu, Staff Writer

posted: 24 February 2009 12:27 pm ET

Imagining dinosaurs in the flesh is tricky since the prehistoric subjects died out some 65 million years ago, but a new tool is helping to fill out the skeleton of T. rex and one of the largest-known duckbill dinosaurs, among other beasts.

Paleontologists used laser imaging technology called LiDAR for the first time to create 3-D computer models of five dinosaurs, including two of Tyrannosaurus rex , a spiny predator called Acrocanthosaurus atokensis, the ostrich-like Strutiomimum sedens and the plant-eating Edmontosaurus annectens, a hadrosaur or duckbill dinosaur.

"Our technique allows people to see and decide for themselves how fat or thin the dinosaurs might have been in life," said Karl Bates, a biomechanics researcher at the University of Manchester in the U.K. "You can see the skeleton with a belly. Anyone from a 5-year-old to a professor can see it and say, 'I think this reconstruction is too fat or too thin.'"

LiDAR has found use in everything from police radar guns to satellite mapping, as well as NASA's Phoenix Mars Lander. Researchers used the technology in this case to scan full mounted dinosaur skeletons, and then digitally reconstruct the body cavity and internal organs such as stomach, lungs and air sac around the 3-D skeleton model.

Having the models allowed the team to change weight estimates and see the possible range of dinosaur fitness. Lower weight estimates probably made the most sense for dinosaurs, because weight affected speed, energy use and demands on the respiratory system.

The larger T. rex specimen at the Manchester Museum in the U.K. may have weighed almost 9 tons, or about as much as the largest African elephant. The smaller T. rex from the Museum of the Rockies in Montana could have weighed anywhere between 6 and 7.7 tons.

"Dinosaurs probably had about 30 percent of their mass in their hind limbs, with the plausible range somewhere between 20 to 40 percent," Bates told LiveScience. "It has been shown in previous studies that giants like T. rex would have needed much more muscle than this in their hind limbs to be the kind of fast runners that are sometimes portrayed as in the media (e.g. Jurassic Park)."

Acrocanthosaurus atokensis would have looked like the younger and wilder cousin to T. rex, boasting large spines on its back and roaming the Earth in the mid-Cretaceous period, around 110 million years ago. Its specimen from the North Carolina Museum of Natural Sciences roughly matched the mass of the smaller T. rex.

The Strutiomimum sedens from the Black Hills Institute of Geological Research in South Dakota weighed somewhere between 882 to 1,323 pounds as a relative lightweight whose name means "ostrich mimic." Incidentally, Bates and his colleagues calibrated the accuracy of their laser imaging by using a modern-day ostrich.

Edmontosaurus annectens hailed from the duck-billed hadrosaur family. The juvenile specimen on hand from the Black Hills Institute weighed in at roughly 2,000 pounds, although it may have matched T. rex for size when fully grown for its own protection.

Bates and colleagues next plan to use their mass estimates to try and figure out dinosaur movement and walking style. Their latest research was detailed last week in the journal PLoS ONE.

"Reconstructing more dinosaurs in such detail will allow us to examine changes in body mass and particularly center of mass as they evolved," said Bates. "As we know, dinosaurs evolved into birds. As they did so, the center of mass moved forward and different walking styles evolved."

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Best estimate reconstruction of Acrocanthosaurus atokensis NCSM 14345

http://www.livescience.com/animals/090224-dino-laser-imaging.html
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Taipan
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legend101
 
Acrocanthosaurus was a very powerful animal. A brief on it:

Acrocanthosaurus Stovall & Langston, 1950 was the top predator of one of the richest faunas known from Early Cretaceous times (Cifelli et al. 1997).
Source: A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA

It could take lot of punishment:


There is evidence in the skeleton of what was probably a near fatal 'hunting accident' in a punctured shoulder blade and several broken ribs that have healed. "Obviously, even this powerful predator had enemies capable of causing it serious damage," said Neal Larson when the injuries were uncovered during preparation.
Source: "Fran" the Acrocanthosaurus atokensis

In spite of these major injuries, the specimen Fran survived.

Acrocanthosaurus is believed to have tackled very large prey, which is very impressive:

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Source: Historical atlas of Oklahoma

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Taipan
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thedinosaurdude
 
PALEOECOLOGY OF AN EARLY CRETACEOUS DINOSAUR TRACKWAY SITE, UPPER GLEN ROSE FORMATION, SATTLER, TEXAS

CAUDILL, Michael J., Department of Geological Sciences, Univ of Kentucky, 101 Slone Building, Lexington, KY 40506-0053, phacops2000@yahoo.com and ETTENSOHN, Frank R., Geological Sciences, Univ of Kentucky, Lexington, KY 40506

In the early 1980s, a surface containing more than 400 individual dinosaur tracks was exposed in the Texas Hill Country near Sattler in Comal County about 50 miles south of Austin, Texas. Only in the last few years has scientific work begun at the site. Approximately 100 million years old, the track layer is located in the upper Glen Rose Formation, a thick, fossiliferous, Lower Cretaceous, marine/marginal-marine unit that is composed largely of chalky limestones, marls and micrites. The trackway site is preserved in a micritic carbonate containing birdseyes, desiccation cracks and ladder-back ripples and is overlain by possibly bentonitic marl containing plentiful clams and plant fragments. Tracks include those made by both herbivores, thought to be Iguanodon-like dinosaurs, and carnivores, thought to be Acrocanthosaurus. Trackways exposed at the site are generally parallel and are oriented northeast, although randomly oriented tracks and trackways are also present. Track-maker identifications are based on Iguanodon and Acrocanthosaurus fossils that are known from equivalent units in southeast Oklahoma. The track site is located on the San Marcos Platform, a small carbonate platform developed on northwest-southeast-trending folds plunging southeasterly from the Llano Uplift to the west. The Glen Rose at this site represents cyclically alternating progradational cycles, resulting from repeated shoreline progradation into shallow, coastal embayments along the Cretaceous Interior Seaway. In this particular situation, it appears that herbivorous dinosaurs were using supratidal mudflats to access coastal marshes, which eventually prograded out over the flats with sea-level rise; carnivorous dinosaurs apparently followed. Although supratidal micrites are not common in this part of the section, this interesting occurrence suggests that some combination of lowstand and the structurally high nature of the small platform may have been responsible for the trackway development, whereas subsequent, rapid flooding may have contributed to its preservation. Hence, subsurface structure and its probable influence on Cretaceous coastal geomorphology may be important in explaining the origin and location of some trackway sites like this.

http://gsa.confex.com/gsa/2004NE/finalprogram/abstract_70164.htm
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thedinosaurdude
 
This is all I could find on a track I saw at the Texas Memorial Museum:
Texas Memorial Museum

Exhibits: Outdoor

Glen Rose Dinosaur Tracks


TMM's dinosaur tracks, which are on display in a small building just north of the Museum's main entrance, were collected from the bed of Paluxy Creek about 5 miles northwest of Glen Rose, Texas. They are among the finest examples of dinosaur trackways ever discovered.

Two trackways can be seen. The broad footprints of the first trackway were made by the hind feet of a sauropod dinosaur that may have been 60 feet long, weighing 30 tons. The distance between prints indicates a stride of almost 10 feet. The deep, post-hole shaped holes were made by the front feet, which were not as broad as the rear feet. A second trackway of three-toed prints was made by a theropod dinosaur. The theropod, walking on hind legs with a stride of about 9 feet, was perhaps 30 feet in length. Its tiny forelimbs were probably too short to reach the ground. The absence of tail-drag marks likely indicates that both dinosaurs held their tails aloft. Some scientists think that the footprints actually document a battle between the theropod and the sauropod—for this reason, TMM's dinosaur tracks have become internationally famous!

In 1939, Roland T. Bird of the American Museum of Natural History (AMNH) traveled to the Paluxy Creek site to collect sections of the trackway as part of a Work Projects Administration (WPA) project jointly supervised by the University of Texas and AMNH. TMM's sections were hammered out of the parent trackway, numbered, transported by truck and train, and eventually reassembled at their destination.
http://www.utexas.edu/tmm/exhibits/trackway/
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Taipan
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EDDY & CLARKE, 2011
NEW INFORMATION OF THE CRANIAL ANATOMY OF ACROCANTHOSAURUS ATOKENSIS AND ITS IMPLICATIONS FOR THE PHYLOGENY OF ALLOSAUROIDEA (DINOSAURIA: THEROPODA)
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0017932
Allosauroidea has a contentious taxonomic and systematic history. Within this group of theropod dinosaurs, considerable debate has surrounded the phylogenetic position of the large-bodied allosauroid Acrocanthosaurus atokensis from the Lower Cretaceous Antlers Formation of North America. Several prior analyses recover Acrocanthosaurus atokensis as sister taxon to the smaller-bodied Allosaurus fragilis known from North America and Europe, and others nest Acrocanthosaurus atokensis within Carcharodontosauridae, a large-bodied group of allosauroids that attained a cosmopolitan distribution during the Early Cretaceous.
Re-evaluation of a well-preserved skull of Acrocanthosaurus atokensis (NCSM 14345) provides new information regarding the palatal complex and inner surfaces of the skull and mandible. Previously inaccessible internal views and articular surfaces of nearly every element of the skull are described. Twenty-four new morphological characters are identified as variable in Allosauroidea, combined with 153 previously published characters, and evaluated for eighteen terminal taxa. Systematic analysis of this dataset recovers a single most parsimonious topology placing Acrocanthosaurus atokensis as a member of Allosauroidea, in agreement with several recent analyses that nest the taxon well within Carcharodontosauridae.
A revised diagnosis of Acrocanthosaurus atokensis finds that the species is distinguished by four primary characters, including: presence of a knob on the lateral surangular shelf; enlarged posterior surangular foramen; supraoccipital protruding as a double-boss posterior to the nuchal crest; and pneumatic recess within the medial surface of the quadrate. Furthermore, the recovered phylogeny more closely agrees with the stratigraphic record than hypotheses that place Acrocanthosaurus atokensis as more closely related to Allosaurus fragilis. Fitch optimization of body size is also more consistent with the placement of Acrocanthosaurus atokensis within a clade of larger carcharodontosaurid taxa than with smaller-bodied taxa near the base of Allosauroidea. This placement of Acrocanthosaurus atokensis supports previous hypotheses of a global carcharodontosaurid radiation during the Early Cretaceous.

BATES, IN PREPARATION
PREDICTING SPEED, GAIT AND METABOLIC COST OF LOCOMOTION IN THE LARGE PREDATORY DINOSAUR ACROCANTHOSAURUS USING EVOLUTIONARY ROBOTICS
http://www.vertpaleo.org/meetings/documents/SVP09AbstractsFULL_WEB.pdf
What were the limits of locomotor performance in large theropod dinosaurs and how was functional morphology adapted to the engineering demands of increased size? In this study I use rigid-body dynamics and evolutionary robotic optimizations to reverse-engineer locomotion in the Cretaceous theropod Acrocanthosaurus. With a mass in excess of 5000kg and the highest femur:metatarsal length of any theropod, Acrocanthosaurus represents the extreme of the non-avian theropod hind limb locomotor module. A 3D musculoskeletal model has been constructed which includes body segment mass and inertial properties and 22 hind limb muscles reconstructed using extant phylogenetic bracketing. The muscle activation pattern has been developed by a genetic algorithm optimization system, which generates gaits de novo and alleviates the need to subjectively infer joint kinematics or rely on extant taxa as locomotor analogues. Maximum running speed optimizations using a best estimate model predict a top speed of 6.8m/s, and an erect running gait characterized by a short aerial phase and modest hip flexion. A sensitivity analysis, in which soft tissue parameters were varied over plausible values for Acrocanthosaurus, reveals a significant range in possible speeds (3.9-7.5m/s) reflecting uncertainty in muscle contractile properties. However, joint excursions vary surprisingly little across this range; the greatest shift in kinematics occurs when trunk centre of mass is shifted to the craniad extreme, which induces increased femoral protraction in late swing and early stance phases. Optimizing metabolic energy expenditure predicts a reduction in the cost of locomotion with decreasing speed. Optimal walking speeds occur between 2.3-2.7m/s where cost of locomotion is comparable to extant bipeds. These gaits show close agreement with stride lengths and predicted speeds from Paluxy River theropod trackways attributed to Acrocanthosaurus. Preliminary results from finite element analysis indicate high bending stresses in flexed femoral postures at the highest running speeds, suggesting large theropods may have been limited to upright limb orientations as predicted here for Acrocanthosaurus.
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Mack
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A documentary from Mega-Beasts (Monster Resurrected) named Great American Predator about Acrocanthosaurus

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Megafelis Fatalis
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Shartman
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Right Click + Open image in a new tab = Larger view
Edited by Taipan, Jan 22 2012, 12:44 PM.
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Temnospondyl
Stegocephalia specialist.
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Dinosaur kings
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dino-ken
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I love this dinosaur. It's my favorite of all the Carcharodontosaurs.

Of Course, this may something to do with the fact of my several visits to the Noth Carolina Museum of Natural Sciences. Which has the only mounted skeleton of this species.
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Big G
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The original description of Acrocanthosaurus atokensis.

http://www.jstor.org/discover/10.2307/2421859?uid=3738296&uid=2&uid=4&sid=21102321986201
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Vobby
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http://onlinelibrary.wiley.com/doi/10.1017/S0952836905006989/pdf

Abstract
Casts of forelimb elements of the Cretaceous theropod dinosaur Acrocanthosaurus atokensis were manually manipulated to determine range of motion and infer function. It was found that the humerus can swing posteriorly into a horizontal position but can neither swing laterally to glenoid height nor anteriorly much beyond the glenoid. The forearm can approach but not achieve full extension and right-angle flexion. Pronation and supination are precluded by immobility of the radius relative to the ulna. Motion also seems to be restricted at the wrist. The palm faces medially, and digital movement is subtransverse. All three digits are capable of extreme hyper-extension. Digits I and II converge during flexion. Only digit III can be abducted or adducted. The limited anterior range of brachial motion infers that Acrocanthosaurus first apprehended prey orally, using the forelimb afterwards to secure its grip or deliver fatal blows. Acrocanthosaurus could only manually grasp prey that was beneath its chest, towards which it may have used its mouth to move prey. Struggling prey would have impaled itself further upon the permanently and strongly flexed first ungual. The range of motion in the forelimb of Acrocanthosaurus resembles that of Herrerasaurus and Dilophosaurus, and exceeds that of Tyrannosaurus. Acrocanthosaurus exhibits a greater manual range of motion than ornithomimid and deinonychosaurian coelurosaurs, but less at the shoulder and elbow. Coelurosaurian theropods exhibit reduced digital flexion and hyper-extension, which suggests a change in the use of the manus in coelurosaurs.
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moldovan0731
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Acrocanthosaurus skeletal made by Franoys:

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