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Tyranosaurus Rex - The dinosaur with huge apetite

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History


Henry Fairfield Osborn, president of the American Museum of Natural History, named Tyrannosaurus rex in 1905. Osborn used the Latin word rex, meaning "king", for the specific name.
The full binomial translates to "tyrant lizard the king" or "King Tyrant Lizard", emphasizing the animal's size and perceived dominance over other species of the time.

Tyranosaurus_rex_


The Tyrannosauridae were giant coelurosaurian theropods from the Cretaceous of Asia and North America.
Tyrannosaurids differ from both smaller coelurosaurs and other large theropods including carnosaurs in the greater robustness of their teeth  and skulls, enlarged areas for attachment and expansion of jaw muscles, and the consequent ability to bite deeply into bone.

 

 

Description

Tyrannosaurus rex one of the greatest carnivores - though not the largest - ever to have walked the Earth, Tyrannosaurus rex (or T-rex) ruled North America during the late Cretaceous period, some 68-65 million years ago.
The massive skull of this mighty theropod dinosaur measured 1.5 metres and was balanced by a long heavy tail. The jaw, filled with huge, saw-edged teeth could deliver a devastating bite. Top predator or mighty scavenger, the 'tyrant lizard king' was without doubt a dinosaur to be feared.
Thirty specimens have been recovered, some of which (such as those named Sue, Stan and the juvenile Jane!) are almost complete. 

Tyrannosaurus_Rex_Holotype


It lived throughout what is now western North America, at the time an island continent termed Laramidia, with a much wider range than other tyrannosaurids.
Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 67 to 65.5 million years ago.
It was among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.

Size: 40 ft (12 m) long; 15 to 20 ft (4.6 to 6 m) tall

Sues_skeleton_

 


Fossil evidence shows that Tyrannosaurus was about 40 feet (12 meters) long and about 15 to 20 feet (4.6 to 6 meters) tall. Its strong thighs and long, powerful tail helped it move quickly, and its massive 5-foot-long (1.5-meter-long) skull could bore into prey.
T. rex's serrated, conical teeth were most likely used to pierce and grip flesh, which it then ripped away with its brawny neck muscles. Its two-fingered forearms could probably seize prey, but they were too short to reach its mouth.

 

Tyrannosaurusscale_
Scientists believe this powerful predator could eat up to 500 pounds (230 kilograms) of meat in one bite. Fossils of T. rex prey, including Triceratops and Edmontosaurus, suggest T. rex crushed and broke bones as it ate, and broken bones have been found in its dung.
Tyrannosaurus rex lived in forested river valleys in North America during the late Cretaceous period. It became extinct about 65 million years ago in the Cretaceous-Tertiary mass extinction.

 

Tyranosaurus_rex_drawing_killing_his_pray

A Tyrannosaurus rex fossil has yielded what appear to be the only preserved soft tissues ever recovered from a dinosaur. Taken from a 70-million-year-old thighbone, the structures look like the blood vessels, cells, and proteins involved in bone formation.
Most fossils preserve an organism's hard tissues, such as shell or bone. Finding preserved soft tissue is unheard of in a dinosaur-age specimen.
To my knowledge, preservation to this extent—where you still have original flexibility and transparency—has not been noted in dinosaurs before, so we're pretty excited by the find," said Mary H. Schweitzer, a paleontologist at North Carolina State University in Raleigh.
The findings may provide new insights into dinosaur evolution, physiology, and biochemistry. They could also increase our understanding of extinct life and change how scientists think about the fossilization process.
"Finding these tissues in dinosaurs changes the way we think about fossilization, because our theories of how fossils are preserved don't allow for this [soft-tissue preservation]," Schweitzer said.
For three years scientists from the Museum of the Rockies in Bozeman, Montana, excavated the T. rex from sandstone at the base of the nearby Hell Creek formation. The dinosaur was relatively small and around 18 years old when it died.
"The dinosaur was under an incredible amount of rock," said Jack Horner, a curator of paleontology at the museum. "When it was collected, the specimen was very far away from a road, and everything had to be done by helicopter.
"The team made a plaster jacket to get part of the fossil out, and it was too big for the helicopter to lift. And so we had to take the fossil apart.

Tyranosaurus_rex_skeleton

"In so doing, we had to break a thighbone in two pieces. When we did that, it allowed [Schweitzer] to get samples out of the middle of the specimen. You don't see that in most excavations, because every effort is made to keep the fossil intact," said Horner, a co-author of the study.
Because the leg bone was deliberately broken in the field, no preservatives were added. As a result, the soft tissues were not contaminated.
The museum, which is a part of Montana State University, has a laboratory that specializes in cellular and molecular paleontology (the study of prehistoric life through fossil remains).
The study authors also looked at several other dinosaur fossils to see whether there was something unique about this particular T. rex fossil.
 "There's nothing unique about the specimen other than the fact that it's the first that's been examined really well," Horner concluded. Other dinosaurs, in other words, are probably similarly preserved.

Soft Tissues

Schweitzer's background is in biology, and she performed a number of tests on the fossils that are common medical practices today.
The paleontologist and her colleagues removed mineral fragments from the interior of the femur by soaking it in a weak acid. The fossil dissolved, exposing a flexible, stretchy material and transparent vessels.
The vessels resemble blood vessels, cells, and the protein matrix that bodies generate when bones are being formed.
"Bone is living tissue, is very active tissue, and has its own metabolism and has to have a very good blood supply," Schweitzer said.
"So bone is infiltrated with lots and lots of blood vessels in its basic structure. When bone is formed, it's formed by cells that are specific for bone, that secrete proteins like collagen and form a matrix."
Further chemical analysis might enable the scientists to answer long-standing questions about the physiology of dinosaurs. For instance, were they warm-blooded, cold-blooded, or somewhere in between?
If protein sequences can be identified, they can be compared to those of living animals. This might allow a better understanding of how different groups of animals are related.
The find may potentially change field practices, perhaps by encouraging more scientists to reserve parts of fossils for cellular and molecular testing.

Skull
Tyrannosaurid theropods display several unusual adaptations of the skulls and teeth. Their nasals are fused and vaulted,suggesting that these elements braced the cranium against high feeding forces.
Exceptionally high strengths of maxillary.

T-Rex_Skull_alberta_Canada

 

Teeth in Tyrannosaurus rex indicate that it could exert relatively greater feeding forces than other tyrannosaurids. Areas and second moments of area of the nasals, calculated from CT cross-sections, show higher nasal strengths for large tyrannosaurids than for Allosaurus fragilis. Cross-sectional geometry of theropod crania reveals high second moments of area in tyrannosaurids, with resulting high strengths in bending and torsion, when compared with the crania of similarly sized theropods. In tyrannosaurids trends of strength increase are positively allomeric and have similar allometric exponents, indicating correlated progression towards unusually high strengths of the feeding apparatus. Fused, arched nasals and broad crania of tyrannosaurids are consistent with deep bites that impacted bone and powerful lateral movements of the head for dismembering prey.

 

T-Rex_Skull_alberta_Canada

The anterodorsal process on the medial side of the maxilla in tyrannosaurids protrudes only a short distance beyond the end of the bone to contact the inner surface of the premaxilla.
The intermaxillary suture of G. libratus has three prominent ridges and grooves above the first four maxillary teeth along the internal surface of the palatal shelf of the maxilla. The vomer overlapped the ventral surface at the back of this process. From a point above the fourth maxillary tooth to the level of the anterior margin of the antorbital fenestra above the eighth maxillary tooth, the internal margin of the palatal shelf is smooth and rounded to form part of the boundary of the internal naris. Behind this point there is a well-defined suture for the palatine.


T-Rex Teeth

Measured and computed properties of theropod maxillary teeth. N, number of teeth measured; CH, average crown height; FABL, average fore, aft basal length; MLBL, averge medolateral basal length; AP str., average anteroposterior bending strength indicator; ML str., mediolateral bending strength indicator; Skull l., skull length. Raw measurements of CH, FABL, and MLBL, not these averages, were used to calculate strength
indicators. Measured_and_computed_properties_of_theropod_maxillary_teeth

 

 

 

 

Habitat


These giant coelurosaurian theropods were lived from the Cretaceous of Asia and North America.
It lived throughout what is now western North America, at the time an island continent termed Laramidia, with a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 67 to 65.5 million years ago.

 Tyranosaurus_rex_

 


Diet


The debate about whether Tyrannosaurus was a predator or a pure scavenger is as old as the debate about its locomotion. Lambe (1917) described a good skeleton of Tyrannosaurus’ close relative Gorgosaurus and concluded that it and therefore also Tyrannosaurus was a pure scavenger, because the Gorgosaurus’ teeth showed hardly any wear.

tyrannosaurus_vs_triceratops


This argument is no longer taken seriously, because theropods replaced their teeth quite rapidly. Ever since the first discovery of Tyrannosaurus most scientists have speculated that it was a predator; like modern large predators it would readily scavenge or steal another predator's kill if it had the opportunity.
Paleontologist Jack Horner has been a major advocate of the idea that Tyrannosaurus was exclusively a scavenger and did not engage in active hunting at all,though Horner himself has claimed that he never published this idea in the peer reviewed scientific literature and used it mainly as a tool to teach a popular audience, particularly children, the dangers of making assumptions in science (such as assuming T. rex was a hunter) without using evidence.

Tyranosaurus_rex_drawing_killing_his_pray


Nevertheless, Horner presented several arguments in the popular literature to support the pure scavenger hypothesis:

Tyrannosaur arms are short when compared to other known predators. Horner argues that the arms were too short to make the necessary gripping force to hold on to prey.
Tyrannosaurs had large olfactory bulbs and olfactory nerves (relative to their brain size). These suggest a highly developed sense of smell which could sniff out carcasses over great distances, as modern vultures do. Research on the olfactory bulbs of dinosaurs has shown that Tyrannosaurus had the most highly developed sense of smell of 21 sampled dinosaurs.

 

Tyranosaurus_rex_
Opponents of the pure scavenger hypothesis have used the example of vultures in the opposite way, arguing that the scavenger hypothesis is implausible because the only modern pure scavengers are large gliding birds, which use their keen senses and energy-efficient gliding to cover vast areas economically.
However, researchers from Glasgow concluded that an ecosystem as productive as the current Serengeti would provide sufficient carrion for a large theropod scavenger, although the theropod might have had to be cold-blooded in order to get more calories from carrion than it spent on foraging (see Metabolism of dinosaurs).
They also suggested that modern ecosystems like Serengeti have no large terrestrial scavengers because gliding birds now do the job much more efficiently, while large theropods did not face competition for the scavenger ecological niche from gliding birds.

 

Tyrannosaurus_Rex_Jurrasic_Park_hunting
Tyrannosaur teeth could crush bone, and therefore could extract as much food (bone marrow) as possible from carcass remnants, usually the least nutritious parts. Karen Chin and colleagues have found bone fragments in coprolites (fossilized feces) that they attribute to tyrannosaurs, but point out that a tyrannosaur's teeth were not well adapted to systematically chewing bone like hyenas do to extract marrow.
Since at least some of Tyrannosaurus's potential prey could move quickly, evidence that it walked instead of ran could indicate that it was a scavenger. On the other hand, recent analyses suggest that Tyrannosaurus, while slower than large modern terrestrial predators, may well have been fast enough to prey on large hadrosaurs and ceratopsians.
Other evidence suggests hunting behavior in Tyrannosaurus. The eye-sockets of tyrannosaurs are positioned so that the eyes would point forward, giving them binocular vision slightly better than that of modern hawks. Horner also pointed out that the tyrannosaur lineage had a history of steadily improving binocular vision.
It is not obvious why natural selection would have favored this long-term trend if tyrannosaurs had been pure scavengers, which would not have needed the advanced depth perception that stereoscopic vision provides. In modern animals, binocular vision is found mainly in predators.

 

Tyranosaurus_rex_mating
A skeleton of the hadrosaurid Edmontosaurus annectens has been described from Montana with healed tyrannosaur-inflicted damage on its tail vertebrae. The fact that the damage seems to have healed suggests that the Edmontosaurus survived a tyrannosaur's attack on a living target, i.e. the tyrannosaur had attempted active predation.
There is also evidence for an aggressive interaction between a Triceratops and a Tyrannosaurus in the form of partially healed tyrannosaur tooth marks on a Triceratops brow horn and squamosal (a bone of the neck frill); the bitten horn is also broken, with new bone growth after the break.
It is not known what the exact nature of the interaction was, though: either animal could have been the aggressor. Since the Triceratops wounds healed, it is most likely that the Triceratops survived the encounter and managed to overcome the Tyrannosaurus.
Paleontologist Peter Dodson estimates that in a battle against a bull Triceratops, the Triceratops had the upper hand and would successfully defend itself by inflicting fatal wounds to the Tyrannosaurus using its sharp horns.

When examining Sue, paleontologist Pete Larson found a broken and healed fibula and tail vertebrae, scarred facial bones and a tooth from another Tyrannosaurus embedded in a neck vertebra. If correct, these might be strong evidence for aggressive behavior between tyrannosaurs but whether it would have been competition for food and mates or active cannibalism is unclear.
However, further recent investigation of these purported wounds has shown that most are infections rather than injuries (or simply damage to the fossil after death) and the few injuries are too general to be indicative of intraspecific conflict.
Some researchers argue that if Tyrannosaurus were a scavenger, another dinosaur had to be the top predator in the Amerasian Upper Cretaceous. Top prey were the larger marginocephalians and ornithopods. The other tyrannosaurids share so many characteristics that only small dromaeosaurs and troodontids remain as feasible top predators.
In this light, scavenger hypothesis adherents have suggested that the size and power of tyrannosaurs allowed them to steal kills from smaller predators, although they may have had a hard time finding enough meat to scavenge, being outnumbered by smaller theropods.Most paleontologists accept that Tyrannosaurus was both an active predator and a scavenger like most large carnivores.

 

 

Interesting Facts

Sexual dimorphism - Several morphological differences associated with the two morphs were used to analyze sexual dimorphism in Tyrannosaurus rex, with the 'robust' morph usually suggested to be female.
For example, the pelvis of several 'robust' specimens seemed to be wider, perhaps to allow the passage of eggs. It was also thought that the 'robust' morphology correlated with a reduced chevron on the first tail vertebra, also ostensibly to allow eggs to pass out of the reproductive tract, as had been erroneously reported for crocodiles.

 

Tyrannosaurus_Rex_Jurrasic_Park_distroying_the_car

  • Tyrannosaurus, like most dinosaurs, was long thought to have an ectothermic ("cold-blooded") reptilian metabolism. The idea of dinosaur ectothermy was challenged by scientists like Robert T. Bakker and John Ostrom in the early years of the "Dinosaur Renaissance", beginning in the late 1960s.Tyrannosaurus rex itself was claimed to have been endothermic ("warm-blooded"), implying a very active lifestyle.
  • Tyrannosaurus may have had infectious saliva used to kill its prey. This theory was first proposed by William Abler. Abler examined the teeth of tyrannosaurids between each tooth serration.The serrations may have held pieces of carcass with bacteria, giving Tyrannosaurus a deadly, infectious bite much like the Komodo dragon was thought to have.

 

T-Rex-Jurassic_Park_

 

  • Cannibalism


A study from Currie, Horner, Erickson and Longrich in 2010 has been put forward as evidence of cannibalism in the genus Tyrannosaurus.
They studied some Tyrannosaurus specimens with tooth marks in the bones, attributable to the same genus. The tooth marks were identified in the humerus, foot bones and metatarsals, and this was seen as evidence for opportunistic scavenging, rather than wounds caused by intraspecific combat.
In a fight, they proposed it would be difficult to reach down to bite in the feet of a rival, making it more likely that the bitemarks were made in a carcass. As the bitemarks were made in body parts with relatively scantly amounts of flesh, it is suggested that the Tyrannosaurus was feeding on a cadaver in which the more fleshy parts already had been consumed.
They were also open to the possibility that other tyrannosaurids practiced cannibalism.

 

Tyrannosaurus_Rex_Jurrasic_Park_toilete


  • Tyrannosaurus means "tyrant lizard."



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Sources :
http://www.bbc.co.uk/nature/life/Tyrannosaurus
http://animals.nationalgeographic.com/animals/prehistoric/tyrannosaurus-rex/
http://blogs.smithsonianmag.com/dinosaur/2012/04/when-tyrannosaurus-chomped-sauropods/?onsite_source=relatedarticles&onsite_
http://www.xinglida.net/pdf/Xu_et_al_2012_Yutyrannus.pdf
http://www.app.pan.pl/archive/published/app51/app51-435.pdf
http://www.app.pan.pl/archive/published/app48/app48-227.pdf
http://damir-g-martin.deviantart.com/art/Tyrannosaurus-Rex-Skeleton-197107746
http://www.deviantart.com/morelikethis/184905954

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