T Rex(Tyrannosaurus Rex)
The tyrannosaurus Tyrannosaurus rex, or, sometimes abbreviated as T.
rex, meaning "king of the tyrant lizards" is the most famous dinosaur family
tyrannosaurids.
It is a carnivorous dinosaur of the suborder theropod that lived in what is now
North America, a period from the late Cretaceous Maastrichtian called between 68
and 65 million years before our era.
It was one of the last non-avian dinosaurs existed before the Cretaceous
extinction.
Like other Tyrannosauridae, Tyrannosaurus rex was a bipedal carnivore with a
massive skull balanced by a long, heavy tail.
Compared to the large and powerful hind legs, the arms of T.
rex were small, though powerful for their size, and had two fingers, and a third
may be vestigial.
Although other theropods rivaled or exceeded T.
rex in size, it is the largest tyrannosaurids known and one of the largest land
carnivores of this era, measuring up to nearly 12 meters long , 4 feet at hip
height
and
weighing up to 6.7 tons .
By far the largest carnivore of its time, T.
Rex has been an Apex predator at the top of the food chain, including hunting
large herbivores such as hadrosaurid Ceratopsia and, although some experts
suggest that it was primarily scavengers.
More than 30 fossil specimens of Tyrannosaurus rex have been identified, some
are almost complete.
Remnants of soft tissue and protein fossils were found on at least one of these
specimens .
The abundance of materials has led to many advances in many aspects of history
and biology of this species.
If some points are consensual, others remain controversial, such as eating
habits, physiology or its speed.
Even its taxonomic place is debatable, some considering T.
rex as the only species of the family Tyrannosauridae while others consider the
Tarbosaurus bataar Asia, substantially identical to the anatomical level, as the
second species of this family.
Several other genera of the family were also tyrannosaurids synonymize with
Tyrannosaurus
Etymology
Tyrannosaurus means "tyrant lizard", a name proposed by Henry Osborn in 1912,
derived from Greek words τύραννος (Tyrannus, "tyrant") and σαῦρος (Sauros,
"lizard") and the Latin word rex, meaning king.
Henry Fairfield Osborn, president of the American Museum of Natural History
called the Tyrannosaurus rex in 1905, he ascribes this name because it was an
impressive predator with claws and huge teeth.
It is often called "T.
rex "(often found the diminutive abusive" T-Rex. "It is wrong because, first,
there is no hyphen in" Tyrannosaurus rex "and, secondly, the point called the" T
"
stands for "Tyrannosaurus" while the link was never this role).
Its old name proposed by Barnum Brown on his discovery, Dynamosaurus Imperiosus
(Saurian dynamic Imperial) will be quickly forgotten
Description
The Tyrannosaurus rex is one of the largest land carnivores of all time.
The largest specimen found so far, listed under the code FMNH PR2081, nicknamed
"Sue", the name of the paleontologist Sue Hendrickson, measuring 11.2 meters
long and 4 meters high, hip height .
The different estimates of the mass of Tyrannosaurus rex have varied greatly
over the years, from the authors of more than 7.2 tonnes to under 4.5
tonnes with the following
latest estimates range from 5.4 to 6.7 tons.
If the Tyrannosaurus rex was larger than Allosaurus, another well-known theropod
from the Jurassic, there was slightly less impressive than the Spinosaurus and
Giganotosaurus, two carnivorous Cretaceous .
As in other theropods, the neck of T.
Rex form a curve shaped "S" to keep its head above the body, but it is
particularly short and muscular to support the massive head.
The arms are short and end with two fingers.
In 2007, a specimen with three fingers on each hand was discovered in the Hell
Creek formation in Montana, suggesting the possible presence of a vestigial
third finger in Tyrannosaurus , a hypothesis to be confirmed .
In proportion to body size, the legs of T.
rex are among the longest of all theropods.
The tail is long and massive, sometimes consisting of over forty vertebrae,
acting as a lever to balance the massive head and torso.
To alleviate the animal and allow it to move quickly enough, many bones are
hollow, reducing weight without significant loss of strength .
The largest skull of T.
rex measuring 1.535 meters (5 feet) in length ].
Large air cavities to reduce the mass of the skull, and left room for attachment
of jaw muscles .
In the first time, paleontologists thought that he stood almost vertically due
to its bipedalism.
But following the discovery of new skeletons and biomechanical studies, there
appears to be held horizontally as the only way for her vertebrae bear its
weight.
The Tyrannosaurus should not exceed 6 meters.
He stood on his hind feet.
His hind legs, terminating in a foot with three toes, claws, were particularly
strong.
Its frontal vision enabled him to effectively assess distances.
To support its huge head, his limbs were atrophied (miniaturized).
His arm muscles were still developing and they had two fingers with sharp claws.
They were probably used to keep food, but were too short (comparable to those of
a man) to be able to pick up ground.
The tyrannosaurus was therefore obliged to look for gnawing carcasses of their
prey.
Some of his teeth, particularly impressive (up to 18 cm long) were crenellated
as meat cutters.
Suppose that one could move his jaw backwards.
Moreover, the fossilized tooth wear shows that chewing food relatively hard.
The jaw of Tyrannosaurus was a phenomenal power.
It is considered the most powerful of all the animal living or extinct: it was
thus able to extract pounds of flesh at once.
Some scientists believe that its bite was poisonous because bits of flesh stuck
between front teeth and breaking away.
It is possible that the T. rex, like other reptiles of that time has been filled
with feathers.
A team of researchers has also recently discovered in a broken femur, soft
tissue (extremely rare).
"The vessels (blood) and their contents are similar to those found in ostrich
bone," said paleontologist Mary Schweitzer.
One element that comes again support the hypothesis that birds are cousins, if
not the descendants of dinosaurs.
This discovery of "soft tissue" has many hopes for future studies
Travel speed
The first biomechanical studies have estimated that it could not run faster than
18 km / h.
This speed is certainly slower than in the movie Jurassic Park, but it should
not be underestimated.
It could (maybe) allow him to take a prey by ambush, and continue on a very
short distance.
Large prey he coveted (sauropods, ceratopsians) were also not very fast.
The hypothesis of a behavioral food-type scavenger has been advanced subsequent
to these studies.
However, the fact that he does not run fast does not necessarily mean it was
carrion.
Slow, it could use other strategies to hunt and trap.
In addition, traces of fossilized footprints show that T. rex could have strides
of 3.75 meters and can estimate its speed at 25 km / h.
Even if it were a sprint (especially if one sticks to the study of
biomechanics), at least it proves that the animal was not what one might call
"slow".
In a more recent study conducted by British scientists, sprint speed was
estimated at 28.8 km / h.
This estimate was established by modeling the three-legged sprint today -
ostrich 55.4 km / h, emu 47.8 km / h and rights 29 mph - and applied to five
dinosaurs including Tyrannosaurus rex.
This study was made using a new model that takes into account many more
parameters of the skeleton, muscles and tendons.
However, the paleontological data are known only to the insertion of muscles and
bones, but the real muscle is still unknown.
Recent discoveries on the structure of T. rex bone possessing a granular
structure similar to that of birds allowed to re-estimate the weight of the
dinosaur to 6 tons.
The latter also used its tail as an energy accumulator for increased speed,
estimated then at more than 40 km / h.
This would explain the traces found and the hypothesis that T. rex would have
been a terrible predator with the ability to hunt effectively in its victims.
Systematics
Tyrannosaurus belongs to the superfamily Tyrannosauroidea, the family
Tyrannosauridae, the suborder Theropoda and order saurischiens.
The family also includes tyrannosaurids Daspletosaurus, dinosaur of North
America and Asia Tarbosaurus .
It was once considered the tyrannosaurids as descendants of the large theropod
Megalosaurus and carnosaur, but they have more recently been reclassified among
cœlurosauriens.
In 1955, Soviet paleontologist Evgeny Maleev Mongolia discovers a new species
that he will appoint Tyrannosaurus bataar.
But in 1965, experts discovered that this species is distinguished from North
American Tyrannosaurus, a new group is created under the name Tarbosaurus bataar.
Many phylogenetic analysis have uncovered that the Tarbosaurus bataar taxon was
the brother of Tyrannosaurus rex, and it has often been considered an Asian
species of Tyrannosaurus.
A new description of the skull Tarbosaurus bataar has demonstrated that it is
narrower than that of Tyrannosaurus rex and the pressure distribution during
bite should be very different, closer to that of Alioramus a
another Asian tyrannosaur [21].
Discovery
In 1874,
A.
Lakes discovered near Golden, Colorado teeth that belonged to Tyrannosaurus.
In the 1890s, J. B.
Hatcher brings together elements of post-cranial in eastern Wyoming.
At the time, paleontologists thought they had found fossils of a species of
large Ornithomimus, but they actually belonged to Tyrannosaurus rex.
The fragments of vertebrae discovered by E. D.
Cope in 1892 and appointed Manospondylus gigas have also been reclassified T.
rex.
The first remains were found significant in 1902 and the animal was described
and named by Henry Fairfield Osborn in 1905.
Discoveries of complete skeletons, in 1988 (Montana) and 1990 (South Dakota),
were significantly evolve our knowledge of T. rex.
In 2006, it was discovered in a femur unearthed in Montana, soft tissue called
medullary bone "that exist today than in female birds.
After demineralization, paleontologists have found that blood vessels retained
their elasticity.
Paleobiology
Paleontologist Jack Horner has found five Tyrannosaurus in the same reservoir.
It implies that they lived in groups.
These individuals could not be attracted by prey or carrion: no remains of
herbivores has been found there.
Jack Horner wondered whether Tyrannosaurus was a hunter or a scavenger.
Indeed it is not a good runner.
However, it would have been a very sensitive nose, offsetting its poor vision
that would have allowed him to easily locate carrion.
However, we found a T. rex bite a Edmontosaurus had healed and the animal died
subsequently.
Scientists always wonder if he ate fresh meat or carrion.
It is also not excluded that it could be both predators and scavengers, as
opportunities presented themselves to him.
By way of comparison, the behaviors can be observed today, it may happen that eg
vultures, scavengers, hunt when hunger drives them.
In contrast, lions, discovering a corpse still fresh, do not hesitate to feed on
it.
They turn out that way, opportunistic.
Scientists have discovered fossils in T.
Rex, traces of gout.
This large carnivore would therefore suffer from acute and sudden pain in the
joints, which would probably play on his behavior
Lifetime
The identification of several specimens of young Tyrannosaurus rex has allowed
scientists to document ontogenetic changes, evaluate the course of their lives,
and to determine the growth of these animals.
The smallest known individual (LACM 28471, the theropod "Jordan") would weigh
only 29.9 kilograms, while the largest, as the specimen FMNH PR2081 (Sue) had
reached well over 5 400 kg (nearly 6 tons
).
Histological analysis of bones of T.
rex showed that the specimen LACM 28,471 was aged just two years, while Sue was
28 years, probably the age limit of this species .
Histology also identified the age of other specimens.
It is possible to draw the growth curves when you can see a graph on the age and
weight of different specimens.
That of T.
Rex was an S curve, the young did not exceed 1 800 kg to about 14 years, and
their size increased significantly.
During this phase of rapid growth, a young T.
rex could earn an average of 600 kg per year for four years.
From 18 years, the curve stabilizes, meaning that the growth of the animal
increases more slowly.
For example, only 600 kg separating the specimen Sue aged 28 years old Canadian
specimen for his 22 years (RTMP 81.12.1) [4].
Another more recent histological study conducted by different scientists
corroborate these findings, demonstrating that the rapid growth begins to slow
from 16 years .
This sharp break in growth rate between 14 and 18 years could testify to the
existence of a phase of physical maturity is synonymous with sexual maturity.
A hypothesis supported by the discovery in 2005 of bone tissue rich in calcium,
also known as the bone marrow in the femur of a T.
rex age 18 (MOR 1125, also known as "B-rex") .
In nature, these bone tissues were found only in mature female birds just before
spawning, they can strengthen the eggshell.
Dinosaurs are also oviparous, the same phenomenon can be intervened at the time
and this finding could indicate that the young "B-rex" was sexually mature .
The same discovery was made at a female Allosaurus aged 10 years and in female
Tenontosaurus aged 8 years, suggesting that sexual maturity in dinosaurs would
have intervened much earlier than was previously thought.
Females dinosaurs could then lay their eggs from pre-adolescence and then become
mothers .
Other tyrannosaurids have growth curves very similar to those of T.rex, although
their growth rates are slower at smaller sizes in adulthood .
The mortality rate increases with the approach of sexual maturity, a pattern
found in other tyrannosaurs, large birds and mammals.
These species include, after a high infant mortality, a high survival rate,
which declined rapidly to sexual maturity.
Mortality increases at sexual maturity, partly due to the stress that
accompanies the female egg.
A study shows that the low number of samples of juveniles is due in part to
their low mortality rate, these animals did not die in large numbers at these
ages
Sexual dimorphism
With the discovery of specimens of many more, scientists have begun to analyze
the differences between individuals and identified in Tyrannosaurus rex, two
distinct morphological types, similar to other species of theropods.
Taking into account their morphology, one was named the morphotype "robust"
while the other was called "slender".
Several characteristics associated with these two morphotypes have enabled
scientists to infer that this was possibly a sexual dimorphism, and the robust
standard was probably female, while the slender type was probably male.
Thus, the pelvis is more robust specimens larger, may be to facilitate the
passage of eggs in the pool during spawning .
Also among the strong type, we find a chevron - bones that protect vital
elements of the ventral part of the tail - smaller at the first caudal
vertebrae, may also be to facilitate the passage of eggs in the genital tract
.
This hypothesis was already proposed by Romer in 1956 to crocodilians .
MUJA-Tyrannosaurus.JPG
In the early 2000s, the existence of sexual dimorphism in T.
Rex has been called into question.
Thus in 2005 a study concluded that the presence of chevrons did not
differentiate what kind of crocodilian, and thus cast doubt on the validity of
this criterion to differentiate the type of T.
Rex .
Also scientists have discovered that the first chevron Sue, a very robust
specimen, was actually located very close to her pelvis, as in some reptiles
males, demonstrating that the position of the rafters too varied to be a good
indicator of sex,
in T.
rex as in modern reptiles .
The existence of morphological differences between the various specimens found
may not be related to sexual dimorphism, but rather to geographical variations,
or variations due to age, individuals are robust older .
In 2009, we know with certainty the sex of a single specimen of T. Rex.
A review of "B.rex" (MOR 1125) has found preserved soft tissue from bone marrow,
a specialized tissue found in birds females modern source of calcium for the
production of shell eggs during
ovulation.
The bone marrow is found naturally in female birds, strongly suggesting that "B.rex"
was a female, and she died during ovulation [27].
Recent studies have shown that the medullary tissue was never found in
crocodiles, which live animals are the closest of dinosaurs with birds.
The shared presence of medullary tissue in birds and theropod dinosaurs
indicates the close evolutionary relationship between the two
Posture
Like many bipedal dinosaurs, Tyrannosaurus rex was so wrong, historically
described as a tripod walking on its two hind legs with its tail using ground
support: with the body almost vertically, just as d
a kangaroo.
This design dates from the rebuilding in 1865 of a Hadrosaurus by the American
paleontologist Joseph Leidy, who was the first to describe a dinosaur bipedalism
.
A replica of T.
rex at the Senckenberg Museum, showing modern view of the posture of T.
rex, on its two hind legs.
Henry Fairfield Osborn, former president of the American Museum of Natural
History (AMNH) in New York, thinking that the animal stood upright, opened the
first reconstruction of a complete skeleton of T.rex in 1915.
It remained standing for nearly a century until its demolition in 1992 .
Around 1970, scientists realized that this upright posture with three-point
support is not anatomically possible, it would have caused dislocation and
deterioration of many joints such as hips or that between the skull and the
first
cervical vertebrae .
The false recovery in the AMNH has inspired many films and paintings until the
1990s when films like Jurassic Park represented the tyrannosaur in a posture
more realistic.
Modern representations in museums, art shows and films Tyrannosaurus rex with
the body almost parallel to the ground and the tail stretched behind the head to
balance
Skin and feathers
In 2004, the scientific journal Nature published a report describing a
tyrannosauroïdé the Dilong paradoxus, an ancestor of T.
Rex has lived in the Yixian Formation of China.
Like many theropods discovered in the Yixian Formation, the fossil skeleton was
preserved in a coat of filamentous structures that have been recognized as
precursors of feathers.
It was also assumed that the Tyrannosaurus and other relatives possessed
tyrannosaurids protoplumes.
However, impressions of skin on large tyrannosaurs show mosaics.
We therefore assume that only young people possessed protoplumes then they lost
during their growth period.
Large animals, in proportion to their volume, surface smaller than the smallest.
So the more an animal is large, it suffers less loss of heat.
The protoplumes
would become unnecessary.
Thermoregulation
It was long thought that the Tyrannosaurus, like most dinosaurs were
poikilothermic, that is to say he had a cold-blooded like reptiles.
In the 1960s, scientists such as Robert T.
Bakker and John Ostrom has suggested that the metabolism of the dinosaurs was
more like that of mammals and birds than that of cold-blooded animals.
Following an analysis of a skeleton, scientists reported that the Tyrannosaurus
rex was homeothermic (warm blooded), thus having a very active life.
Since then, several paleontologists have sought to determine the ability of
Tyrannosaurus to regulate its body temperature.
Locomotion
There are two issues which the debate on capacity locomotives Tyrannosaurus: how
could he turn and what is its speed.
The Tyrannosaurus had to be slow to return, it would probably take him 1 to 2
seconds to turn 45 degrees - as compared to human who stands and who has no tail
can turn into a fraction
second [42].
The ornithischian also show evidence of homeotherms, whereas this is not the
case for monitor lizards that lived in the same formation.
Even if Tyrannosaurus rex shows evidence of homeothermy, this does not
necessarily mean that it was endothermic.
Such thermoregulation may be explained by the gigantothermie, like some sea
turtles
Food
The debate concerning the behavior scavenger or predator Tyrannosaurus is so old
that its locomotion.
During the first Tyrannosaus discovery, most scientists were convinced that the
T.
rex was a predator, although like many modern predators, it could be both
predator and scavenger.
Jack Horner is the chief advocate of the theory of Tyrannosaurus scavenger.
Horner has presented several arguments defending this hypothesis:
*
The arms of Tyrannosaurus were short compared to those of known predators.
According to Horner, the arms were too short to have the strength to maintain
its prey.
*
The Tyrannosaurus had large olfactory bulbs and nerves (relative to the size of
their brain).
This implies that they had a well developed sense of smell that would have
allowed them to identify carcasses at large distances like modern vultures.
Research on olfactory bulbs of 21 dinosaurs show that T. rex had the most
developed sense of smell.
*
The teeth of T. rex could crush the bones and carcasses then extract as much
food (bone marrow) as possible, usually the least nutritious parts.
Karen Chin and his team have found bone fragments in coprolites (fossilized
dung) that they attributed to Tyrannosaurus, but they indicate that T. rex's
teeth were not always suitable for grinding bones like hyenas.
*
As the potential prey of Tyrannosaurus could move quickly, evidence that he
could not run fast show it was a scavenger.
On the other hand, recent analysis shows that the Tyrannosaurus although slower
than some modern terrestrial predators, could be fast enough to hunt large
hadrosaur and ceratopsians.
Other evidence suggests a predatory behavior.
The orbits of Tyrannosaurus were put forward, thus giving it binocular vision
which enabled him to judge distances, much better than modern hawks.
The most modern predators have binocular vision which is very important to them.
According to some scientists, whether Tyrannosaurus was a scavenger, another
dinosaur should be at the Apex predator Amerasian Upper Cretaceous.
Prey at the top of the food chain were marginocéphales and ornithopods.
Some paleontologists accept the hypothesis that the Tyrannosaurus was both
predators and scavengers, like many large carnivores.
The Tyrannosaurus in popular culture
Since its discovery in 1905, the tyrannosaurus dinosaur became the most famous
in popular culture.
It is the only dinosaur whose scientific name Tyrannosaurus rex is known to the
general public, even the abbreviated T.
Rex was also widespread.
Exposures of Tyrannosaurus are very popular with an estimated 10 000 visitors
came to the Field Museum in Chicago in 2003 to see Sue, the fossil's most
comprehensive statement.
T. rex appeared several times on television and in movies, including The Lost
World, King Kong, Fantasia, One Million Years BC, and several film versions of
cartoons with Godzilla (monster beliefs of postwar
following the shocks of the atomic bombs of Hiroshima and Nagasaki) as heroes,
and Jurassic Park.
Many books and comic strips, including Calvin and Hobbes, and the manga by
Masashi Tanaka Gon, also represented the tyrannosaurus, which is often shown as
the largest and most terrifying carnivore of all time.
The rock band T-Rex, took this name after species, the band's third album is
titled The Hives Tyrannosaurus Hives.
Movies
* One of the most famous apparitions of the Tyrannosaurus in Jurassic Park was
designed in 1993 by Steven Spielberg.
You can see dinosaur escaping from his enclosure and go hunting for the park
visitors and employees.
*
In the Lost World, a Tyrannosaurus is caught and taken to San Diego.
*
In the Rite of Spring a passage from the film Fantasia, produced by Walt Disney
Pictures, a terrifying Tyrannosaurus and other dinosaurs engaged in battle with
a Stegosaurus.
* In
King Kong, made in 1933 by Merian C.
Cooper and Ernest B.
Schoedsack, the famous monkey faces a Tyrannosaurus to protect the young wife
Ann. Jack.
But in reality this is not a T-Rex that Kong faces but Vastatosaurus rex, an
evolution of the imaginary T-Rex (yes millions of years have passed, if the
T-rex had not changed since
time is that there is a
problem).
The Vastatosaurus rex is often abbreviated as V-rex.
*
To create the famous Japanese monster Godzilla, Toho designers were inspired to
Stegosaurier plates back of the head for Tyrannosaurus and Allosaurus Body
