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Tyrannosaurus rex
JW T-Rex
Information
Common Name T-Rex or T. Rex
Range North America ( Canada, U.S.A, and Mexico)
Scientific Classification
Kingdom Animalia
Phylum Chordata
Class Reptilia
Order Dinosauria
Family Theropoda

Tyrannosauridae

Genus Tyrannosaurus Rex
Species Tyrannosaurus rex
Conservation Status
EXSpecies
Extinct

Tyrannosaurus rex was a theropod dinosaur and the most well known of all dinosaurs that once lived in what is now North America, which was then an island continent known as Laramidia, from Canada to the USA and Mexico. From 68 to 65 million years ago at the end of the Cretaceous period. Tyrannosaurus was the largest member of the tyrannosaurians, and was the top predators of the ecosystem. It possibly was able to take down prey like Triceratops, Pachycephalosaurus, Ankylosaurus, and Edmontosaurus.

Discovery and naming[]

Description[]

They were large with small but strong two fingered arms, equipped with sharp & sickle-shaped claws. Males may have used their arms to hold on to females during mating. It has always been assumed that tyrannosaurs were scaly skinned, however, the discovery of Yutyrannus which had feathers suggests that T-Rexes may have had feathers too. Recent studies show that T-Rexes were indeed scaly skinned & their skins were similar to those of crocodilians. But they may have been mostly scaly skinned with hair-like feathers covering parts of the body. Most T-Rexes grew 12 meters long, but some would have reached 13 meters in length. A T-Rexes’s skull is huge & its snout & lower jaw were very deep. The whole mouth was massive and contained 60 serrated teeth, all them were different sizes with some up 20cm long. A tyrannosaur’s body was heavily built & its cavity was wide, to improve its mobility, some of its vertebrae had holes that can help reduce weight to the animal. The hind legs of a T-Rex were large & muscular which were connected to the body via a lizard-hip arrangement, the size of the legs would have gave the dinosaur an excellent pushing power. But due to its size & small strides it couldn’t have run too fast (compared to other theropod-type Dinosaurs). The tail of a T-Rex was used to balance is body horizontally & essential for chasing down prey.

Paleoecology[]

Paleobiology[]

Tyrannosaurus rex was one of the largest of the theropod dinosaurs and easily the largest predator in its environment. It had a massive skull with reinforced banana-like teeth. Recent studies have estimated that T. rex was capable of biting down with 64,000 N (over 6 tonnes) of force, making it one of the most powerful bites ever known. This amount of force was capable of not only piercing, but completely shattering bone and armor, which would explain why its teeth were so robust, reinforced, and relatively blunt, used for attacking large prey, and crushing smaller prey like Ornithomimids. It likely formed such devastating features in order to prey on well-defended herbivores such as the three-horned Triceratops and Torosaurus, which would in turn evolve more defenses and make a vicious cycle of an evolutionary arm's race. While it was originally hypothesized that T. rex might have had flexible parts of its skull like modern relatives such as parrots and lizards, recent studies involving 3D imaging compared stresses on its head revealed that the bones in its skull would instead have been fused like a crocodile in order to reinforce it and keep it from breaking apart due to the massive amount of force its jaws could deliver.

In life Tyrannosaurus would have had eyes the size of softballs and were capable of seeing long distances with very good depth due to them being forward-facing, giving it binocular vision. CAT-Scans of the skull have revealed that much of the brain was dedicated to its sense of smell, giving T. rex one of the strongest senses known in any modern or extinct taxa. The structure of bones around its ear would have been well suited to picking up low-frequency sounds like modern-day elephants do, indicating that T. rex and its prey were making deep low-frequency noises. Because Tyrannosaurus lacked a larynx like modern mammals such as lions and even likely lacked a syrinx such as those found in modern birds, it is unlikely that it was capable of roaring in a traditional sense as is often depicted in pop culture. Instead, it is believed that T. rex would have done low, deep rumblings and hisses, along with the occasional bellows and "roars" similar to living crocodiles. From specimens such as Jane and B-Rex (MOR 1125), researchers were able to make a growth chart of Tyrannosaurus rex and found that once it hit its pubescent years, T. rex gained an average of 600 kg (1,300 lbs) a year until it hit adulthood at around 18 years of age. No eggs or hatchlings have been found of T. rex yet so what exactly it would have looked like at this stage of its life is not currently known. Because of this some scientists have suggested that this was because these animals rarely died during this age, though others have pointed out that this could simply be due to bias in the fossil record, which doesn't preserve small animals as well as larger ones. The oldest confirmed age for any Tyrannosaurus is currently 28 and belongs to Sue. At this age Sue was already showing signs of age due to arthritis and suggests that even though it didn't die due to old age it still was getting close to the end of its lifespan. It's unlikely T. rex lived much older than 30 years of age, suggesting they lived fast, hard lives.

For some time it was unknown just what Tyrannosaurus' integument consisted of. The classic depiction is that of lizard-like scales entirely covering its body, just like all dinosaurs were thought to have been like at the time. However, as time went on and more fossils were found that depicted dinosaurs with feathers, the question started to arise as to whether all dinosaurs would have had feathers in some way, including Tyrannosaurus rex. This seemed to become more possible when a decently-sized relative of T. rex, Yutyrannus, was found to in fact have been covered in feathers. This lead to the influx of paleo artists challenging the past depictions of the tyrant lizard by covering it from head to toe in downy feathers.

However, a study in 2017 showed that skin impressions of several derived tyrannosaurs, including T. rex itself, depict not the downy feathers that many experts had been expecting, but in fact small, reticulated scales. Although the skin impressions have only been in scattered patches among several species, the researchers concluded that there are enough scale impressions among so many different parts of the individual bodies that it's more likely that scales covered the entire animal instead of feathers only covering places that happened to not be preserved. This was further explained to be the case due to the animal's large body, which at its size any extra integument would have been a detriment rather than a benefit, especially since it lived in such a warm environment. There was a hypothesis for a while that perhaps the young tyrannosaurs would have had feathers when they were hatched and gradually lost them as they aged and grew in size. However, several researchers have pointed out that no animal today completely changes integument as it ages. Even birds today such as turkeys and vultures don't gain scales when they grow out of their facial feathers, it's just bare skin, so that hypothesis has been abandoned. If T. rex did have any feathers in life it would have been light downy feathers along its back similar to elephant hair.

T rex

Pack of T. rex. (Prehistoric Park)


Classification and Evolution[]

Tyrannosaurus is a genus of coelurosaurian theropod, aswell as the type genus of the superfamily Tyrannosauroidea, the family Tyrannosauridae, the subfamily Tyrannosaurinae, and the tribe Tyrannosaurini.

Dinosauria
Saurischia
Theropoda
Coelurosauria
†Tyrannosauroidea
†Tyrannosauridae
†Tyrannosaurinae
†Tyrannosaurini
Tyrannosaurus
Tyrannosaurus rex


Extinction[]

T. rex went extinct during the K-T mass extinction, about 65 million years ago. This extinction killed the remaining dinosaurs (not just T. rex) and many other animal and plant groups.

Gallery[]

Facts[]

  • Tyrannosaurus has the strongest bite force of any known dinosaur.
  • It is probably the biggest meat eating dinosaur in North America.
  • It had a very close relative in Asia, Tarbosaurus.
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