Tyrannosaurus rex

**Tyrannosaurus rex** (Tyrannosaurus is greek for "Tyrant Lizard" and rex latin for "king", making it the "Tyrant Lizard King") is a genus of *carnivorous,* Theropod dinosaur, one of the last dinosaurs to go extinct during the "**K-T extinction event**", and the last and largest genus of the *tyrannosaur* theropod family. The T.rex inhabited forested river valleys of late *Cretaceous* North America (Maastrichtian), 68-66 million years ago. Tyrannosaurus rex was also one of the largest *land carnivores* of all time averaging forty-feet from head to tail, approximately twelve feet high at the hips, and with weights ranging from 6-8 tons. The largest complete specimen (cataloged **"**FMNH PR 2081"), nicknamed sue, measured forty-two feet in length, almost 13 feet at the hips, with a mass of 8.87 tons (some estimates range as high as 13-15 short tons, which is highly unlikely).

## Statistics

### Length

40 ft (12 m average)42 ft (12.8 m specimen Sue)

### Mass

6-8 tons (average)13-15 tons (upper range)

### Diet

Carnivorous (Triceratops, Ankylosaurus and Alamosaurus)

## Distrubution

The T.rex inhabited forested river valleys of late Cretaceous North America (Maastrichtian), 68-66 million years ago

Although, there were larger predators, none of them had a bite force of 8-12,000 pounds, more than enough to crush bone, the equivalent of an adult male Tyrannosaurus slamming down on it's prey. That would make the T.rex the hardest biting terrestrial animal ever, in comparison, the average adult human bites down with a force of a mere 162 pounds.

The T.rex also had the biggest teeth of any land animal to ever exist, maxing out at twelve inches, sixty of them lining it's massive, four to five foot jaw. One feature of Tyrannosaurus that everyone makes fun of is it's disproportionality small arms. The facts is that the arms of Tyrannosaurus over three feet long, and were capable of bench pressing 400 pounds, each. T.rex anyways didn't have the smallest arm-to-body-ratio of the theropod dinosaurs. That honor belongs to the Carnotaurus, whos arms looked like tiny nubs

## Fossil History

### Discovery

In the year 1900, Wyoming, assistant curator of the **American Museum of Natural History** *Barnum Brown* stumbled upon the very first (but incomplete) skeleton of the king of the dinosaurs, composed of three vertebrate, humorous, femur and two unidentified bones. A second skeleton was found in 1902, Montana in the "Hell Creek formation", which was composed of over thirty-four bones.

Over two decades earlier in 1874, Golden, Colorado the very first Tyrannosaurus teeth were discovered by Arthur Lakes, which scientists back in the day were still debating which dino the teeth belonged to. Henry Fairfield Osborn, president of the American Museum of Natural History, named the second skeleton "Tyrannosaurus rex" in 1905.

### M. gigas

In 1892, American paleontologist Edward Drink Cope discovered two fragments of vertebrate which was thought to have belonged to a ceratopsian. Cope named the so-called "ceratopsian" *Manospondylus gigas* (greak for "giant thin vertebrate"), though in 1907, John Bell Hatcher identified them as the bones of a theropod, not a ceratopsian. Ten years later, Osborn noiticed the similarites between *M. gigas* and T.rex. The genus *M.gigas* was then discarded, and was considered to be the genus Tyrannosaurus.

## Possibly Feathered

It is considered a fact that all dinosaurs, especially theropods, were covered in feathers some point during their life cycle, most likely when they first hatched. The feathered dinosaurs theory was backed up when scientists discovered the feathered Tyrannosaurs "Yutyrannus huali" (mandarin for "feathered tyrant") and "Dilong paradoxus" ("beautiful feathered tyrant") in China. Even though there is no concrete evidence for a feathered T.rex, until new specimens are discovered, we can't now for sure.

## Size

Unknown to most, Tyrannosaurus was actually one of the **smaller** *carnivorous* dinosaurs of the Mesozoic era, though still extremely large by *relative standards*. The exact size of T.rex is still a matter of debate, with mass estimates ranging from five to fourteen tonnes (5.5 to 15.4 tons). Though a weight of 6 to 8 tonnes and a length of 12 to 13 metres from head to tail is more likely.

### Sexual Dimphorism

Based on the analysis of *discovered fossils*, scientists have come to the conclusion that female T.rex were larger than the males, outweighing them by a couple thousand pounds (not to much for a fully grown *Tyrannosaurs*), which is referred to as "**sexual dimphorism**", and were likely more aggressive. There are two theory's to why this is:

1. Due to the fact that females had to lay roughly twenty T.rex-sized eggs or so at a time, the evolved slightly *higher hips*.
2. Another plausible explanation is that the females were simply more successful hunters then their male counterparts, as is the case with modern-day **lions**.

Generally, females have a weight of eight tons while the males average 6-7 tons.

## Tyrannosaur Family Tree

"Tyrannosaurs" are a group of "coelurosaurian" predatory dinosaurs, the majority of which lived during the late Cretaceous period (turian to maastrichtian), in between 77-66 million years ago. The largest and last member, the Tyrannosaurus rex was one of the last dinosaurs to die out during the K-T extinct event, wiping out 65 percent of all life on earth. Other members of the tyrannosaur group are:

* Teratophonues curriei
* Lythronax argestes
* Daspletosaurus torosus
* Tarbosaurus bataar
* Nanotyrannus lancensis
* Nanuqsaurus hoglundi
* Zhuchengtyrannus magnus
* Bistahieversor sealeyi
* Dilong paradoxus
* Yutyrannus huali
* Eotyrannus lengi

However, in 2006, a new dinosaur name "Guanlong" (Chinese for "crown dragon") was unearthed in China, which since it's discovery is classified as a *Tyrannosaur*. The fossils date back to the late Jurassic period, 160 million years ago, some 80 million years before any **discovered** Tyrannosaur was to be seen again, making it the oldest known member of the tyrannosaur family to date. Oddly enough, Gualong was the size of an average dromaeosaur (raptor), at three metres from head to tail. In fact, tyrannosaurs are actually closely related to dromaeosaurs, with tyrannosaurs like Dilong and Eotyrannus being about the size of your standard raptor.

### What Defines a Tyrannosaur?

Tyrannosaurs tend to resemble one another more similarly then other groups of dinosaurs (except in-terms of size, which varies greatly among different species). Typically, "tyrannosaurs" (Greek for "tyrant lizard") are best described as large, *bipedal* carnivores with a robust physique, short but incredibly powerful arms (for there size), and massive skulls.

## Trivia

* The exact speed of the Tyrannosaurus is still a matter of debate, with some stating that it was really the speedy tank it was in Jurassic park (24-43 mph), whiles some **scientists** say that it could barely walk, running at a mere 10 mph.
* For years, scientists debated weather the mighty T.rex was a viscous hunter or a opportunistic scavenger (did it battle it's prey or feed on the carcasses of already dead dinos?). In the end, there's no reason why the T.rex couldn't have indulged in both behaviors, as would any apex predator that would want to avoid being starved to death.
* The jaw muscles of the T.rex were huge, bigger than that of any other meat-eating dinosaur or **land animal** to ever exist. Scientists examining a Tyrannosaurus skull in 1996 at Stanford University calculated it chomped down with a force of 7-9,000 pounds. *Recent* estimates suggest a biting strength of almost 12,000 pounds, more than enough to crush bone (the strongest of any terrestrial animal ever).
* In real life (not Jurassic world), the Tyrannosaurus rex had the best vision of any animal to exist. It's eyes were forward facing, giving it a excellent degree of binocular vision. It's eyesight was 12 times better than a human, 7 times greater than a hawk, 6 times greater than a eagle and 2 times better than that of a Great White Shark.
* The arms of the T.rex were capable of curling 400 pounds each, three times stronger than that of an adult human, making them unusually powerful for their three-foot size.
* Assessing an animals life-span from their fossilized remains is a difficult task. However, based on examinations of existing skeletons, palaeontologists believe that the Tyrannosaurus rex may have lived as long as thirty years (since it was the apex predator of it's time, it likely died from old age or infection rather than attacks from other dinosaurs).
* The Tyrannosaurus had the largest teeth of the theropod dinosaurs, **maxing** out 20-30 cm (8-12 in) in length. Scientists have proposed that the shards of rotten meat continuously getting logged in its closely-packed teeth gave the T.rex a *infectious* bite.