Tyrannosaurus Rex (T-Rex)

Tyrannosaurus Rex (T-Rex)

The greatest destroyer in history


  • Name: Tyrannosaurus Rex (T- rex)
  • Diet: Carnivore
  • Weight: 7 tons
  • Period: Upper Cretaceous
  • Found In: North America

If you ask anyone about a dinosaur, they will almost 100% likely think of a Tyrannosaurus rex (T.rex). T.rex is a myth. We’re not just talking about the king of dinosaurs, but possibly the most terrifying and violent creature that ever lived.

Are you a fan of Tyrannosaurus (incorrectly called “Dinosaur Rex” by many)?

If the answer is yes, be prepared to discover everything you’ve ever wanted to know about this fascinating T-Rex. His life, his family, where he lived, what he ate and his imposing physical conditions.

But at Dinosaurs we don’t just stand there and bring you a lot more. We tell you everything. Can you imagine what King Kong’s fight against a T.rex would be like, or better yet, do you want to know what an autopsy on this T-Rex would be like?

You just have to start reading, I assure you you’ll forget to blink.


The family: tyrannosaurid theropod

Big, powerful and fierce.

So is our Tyrannosaurus rex. He’s got it all to be the most famous dinosaur there is. Although if you think about it, something runs in the family.

Our T.rex is a tyrannosaurid theropod. And now you’re wondering, and what does that mean?

Theropods (Theropoda means “beast’s foot”) are carnivorous dinosaurs that used to stand on two legs (bipeds). In contrast, the term tyrannosaurid refers to large “tyrannical” lizards, dinosaurs with large, prominent skulls, almost no neck and short forelimbs (what we might call the arms).

With a surname like “tyrant”, you couldn’t expect this dinosaur to be a friendly and gentle creature.

Let’s check his genetic tree:

T- Rex Taxonomy

  • KINGDOM: Animalia
  • IDF: Chordata
  • CLASS: Archosauria
  • SUPERORDER: Dinosauria
  • ORDER: Saurischia
  • SUBORDER: Theropoda (theropods)
  • SUPERFAMILY: Tyrannosauroidea (Tyrannosaurids)
  • FAMILY: Tyrannosauridae (Tyrannosauridae)
  • SUBFAMILY: Tyrannosaurinae
  • TRIBU: Tyrannosaurini
  • GENDER: Tyrannosaurus
  • SPECIE: T. rex

With the family tree of our T. rex there has also been controversy. Brothers who were cousins, unrecognized brothers… Quite a story.

Our cousin the exotic: the Tarbosaurus baatar

Fossils of this theropod have been found in Mongolia and various parts of China.


The controversy comes because some scientists consider the Tarbosaurus baatar as just another specimen of Tyrannosaurus rex. The only difference would be that the T.baatar lived in Asia, while our T.rex was American. However, for other paleontologists, they are different genres.

Of course, what is certain is that the two were very closely linked.

Manospondylus gigas: the unrecognized father

As I was saying before, in the family of our T.R.E.C. there have been their ups and downs. Let’s go with one of the most controversial problems, worthy of the magazines of the heart.


It was 1892 and the paleontologist Edward Drinker Cope found two partial vertebrae of a dinosaur. At first, Cope attributes its origin to a ceratopsid (dinosaurs with horn) and calls his discovery Manospondylus gigas.

A few years later, Henry Fairfield Osborn (paleontologist and president of the American Museum of Natural History) admitted the enormous similarity between the Manospondylus and the Tyrannosaurus. However, it was never recognized that they were of the same family or genus, let alone the same species.

We are now making a small leap in time and planting ourselves in the year 2000. A team from the Black Hills Institute locates more remains of the same dinosaur Cope found more than 100 years ago. The tests showed that T-Rex and Handspondylus were the same.

A debate then arose, should the name of Tyrannosaurus rex be changed to Manospondylus Gigas?

In the opinion of many, it should be changed, as it is the oldest name. The name’Tyrannosaurus rex’ was given to it by Osborn in 1905.

However, for many others, it was an aberration to change the name of such a well-known dinosaur.

The end of the controversy was the International Commission on Zoological Nomenclature (ICZN). ICZN determined that a name, even if incorrect, could not be changed after being used for more than 50 years.

Therefore, we can say that the Manospondylus was the first fossil found of T.rex, but to change the name, nothing at all.

In fact, if any paleontologist tried to challenge this decision, the ICZN would most likely call Cope’s name as nomen oblitum (forgotten name) and Osborn’s as nomen protectum (protected name).

Dynamosaurus: more last name problems

Our Tyrannosaurid must have had a complex childhood as he had many problems with his identity.

We have just seen that our T.rex could have been called Manospondylus, since the same happened with the name Dynamosaurus imperiosus.

It was the year 1900 and in the town of Wyoming, there was a specimen of dinosaur that would be called Dynamosaurus.

At that time, a complete copy of T.rex had not yet been discovered, so it could not be compared with this copy. A few years later, it was Osborn again who would see that it was the same genre.

But this time, it was the name Tyrannosaurus rex that was inscribed earlier. For very little, it is said that just by a single sheet of difference, but it was enough to make this the name of the most famous dinosaur in history.

What does the scientific name Tyrannosaurus rex mean

After all the trouble we’ve seen, there has been in giving this theropod a name, what less than knowing what the famous Osborn name really means: Tyrannosaurus rex. The translation would be: “the king of tyrannical lizards“.

We cannot deny Osborn that he got the name right because, for many people, the T.rex is the king of dinosaurs.


Who discovered the T- Rex?

We have already named some of the most important proper names in the history of our Tyrannosaurus, but certainly not all.

We get on our time capsule and go through all the findings that have been made of T.rex.

Colorado (1874): Paleontologist A. Lakes finds some tyrannosaurid teeth, although it would take many years before it was known that they corresponded to a T.rex.

Wyoming (1875): J. B. Hatcher discovers fossils of a post-cranial bone. They were thought to belong to an Ornithomimus (O. grandis).

South Dakota (1876): Edward Drinker Cope finds two partial vertebrae (one disappears). Cope calls the dinosaur Manospondylus gigas, as we have seen, later we would see that these bones corresponded to a Tyrannosaurus rex.

Wyoming (1877): Barnum Brown would discover a skeleton and name it Dynamosaurus imperiosus. Although as we have seen, questions of fate, this name was forgotten. Brown is considered the discoverer of T.rex and Ankylosaurus. He worked at the American Museum of Natural History as a curator.

Montana (1878): Brown finds a second skeleton of Tyrannosaurus. This will be the one taken from reference Henry Fairfield Osborn to make his description of the theropod. Osborn gives it the name Tyrannosaurus rex. Brown came across five partial skeletons of the T.rex.

Without reference to the place (1966): Harley Garbani finds what is considered the largest skull of this Tyrannosaurus ever found.

Buffalo (1967): Stan Sacrison was discovering a partial skeleton of this dinosaur. “Stan”, as he was baptized, had several broken ribs and an important hole in his head. It is more than likely that Stan was shot down by another T.rex (the size of the hole coincided with the dimensions of a tooth of this tyrannosaurid).

South Dakota (1968): Amateur paleontologist Susan Hendrickson found the most complete skeleton seen to date. 85% of the total was recovered. Sue’s” remains led to a legal battle won by the owner of the land, Maurice Williams. I’d make almost $8 million selling the skeleton at auction.

South Dakota (1969): A team from the Black Hills Institute discovers where Cope had found the two vertebrae of M. gigas and begins an excavation where they would find more remains. You can see that the bones correspond to a T.rex. The debate on a possible change of name begins. The ICZN decides to keep the name Osborn.

Montana (2000): Jack Horner finds 5 specimens of Tyrannosaurus. One of them the longest known.

Latest findings or breakage of the bone

In 2005, Dr. Mary Higby Schweitzer and a group of paleontologists announced an unprecedented fact: they found soft material inside the femur of a Tyrannosaurus rex. The importance of this finding lies in several points:

On the one hand, it is very strange to be able to find remains of this type of material after so many, many years (about 70 million).

On the other hand, the doors are open for analyses that would close many debates about Tyrannosaurus (for example, whether or not he was hot-blooded). Also, there may be the option of extracting some stem cells.

Intentional or unintentional breakage

It is strange to think that a bone can be broken when treated with the utmost delicacy. It was therefore even speculated whether Dr. Schweitzer could have deliberately broken it.

One of the paleontologists defended himself against the accusations with a somewhat ambiguous statement: “It is not usual to find bones of a dinosaur, even less of a T.rex, and when we have them we treat them with great care. Nobody goes around making holes or breaking bones to analyze the inside…. although there are some very interesting things in there.

When and where Tyrannosaurus rex lived

To know when the T.rex lived we have to go back to the Cretaceous period, specifically, to the Maastricht.

So you can get a better position, I’ll give you a little outline:

There are four geological eras: Precambrian, Paleozoic, Mesozoic, and Cenozoic.

The Mesozoic is where the dinosaurs lived. This era began about 250 million years ago and lasted about 140 million years. Like I always say, a day up, day down.

The Mesozoic is divided into three other stages: Triassic, Jurassic, and Cretaceous. The latter is where the Tyrannosaurus rex lived. Specifically, as we saw earlier, in the Maastricht.

This is the last period until the dinosaurs disappear. The fall of the meteorite that caused its extinction would start a new geological era, the Cenozoic one.

Therefore, we can perfectly imagine a T.rex running after a dam, while we watch a huge meteorite approaching dangerously close to the Earth. Quite a picture, isn’t it?

As for where they lived, all the fossils that have been found were in western North America.

What this Tyrannosaurid was like, characteristics

Thanks to the films we all visualize this T-Rex to perfection. In bipedal position, a large head, two very short upper extremities, a large tail and two very powerful legs.


But was the T.rex really like that?

In general terms, yes, but there is one thing that needs to be clarified.

How tall was this Tyrannosaurid

It could reach a length of about 13 meters and a height of about 4 meters. This last measure goes up to the hips and is related to the position adopted by the Tyrannosaurus rex. Their weight ranged from 6 to 8 tons.

We usually imagine the T.rex in a vertical position, as if it were a human. We have this image of him because the first representations that were seen in museums supported this vision.

Over time, it has been shown that this Tyrannosaurus posture would be impossible as it would have meant that the hips and other bones would dislocate.

The actual posture is bipedal, but his body leaned so far forward that his head and tail were at the same height.

The physical appearance of T.rex

One of the most spectacular parts of the Tyrannosaurus is its head. Enormous and elongated, it could be up to five feet long. In addition, his narrow muzzle allowed him to have a better view.

Their teeth are also spectacular how big they are. The record is one of 30 centimeters (including the root), being the largest dinosaur tooth ever found.t-rex

On the other hand, his neck was very short and strong, bear in mind that he had to support the weight of his head.

The upper extremities were very short and each one had two claws. Yeah, two and not three. The T.rex has been represented with three claws by a skillful play by our dear friend Henry Fairfield Osborn. When the first skeleton of T.rex was discovered, it was decided to exhibit it to the public. A problem arose in the assembly, I didn’t have the upper extremities.

What happened?

For Osborn, president of the American Museum of Natural History, so that the skeleton would not look incomplete, placed the claws of Allosaurus. And this dinosaur’s “arms” do have three claws.

There has been speculation as to the strength or otherwise of the’arms’ of this tyrannosaurid, as they look a bit’lazy’ compared to the rest of the body.

This would be an erroneous assessment according to the paleontologist of the American Museum of Natural History in New York, Jack Conrad, “the biceps of a T.rex could have lifted weights of up to 200 kilos”.

What did Tyrannosaurus rex use his arms for?

There has been much speculation around this question and 3 different theories have been considered.

  1. They were used to hold the female at the time of copulation.
  2. He leaned on them to get up from the floor when he was lying down.
  3. They served to hold the prey while he bit them with his jaws.

The legs of the Tyrannosaurus were already much more powerful, let’s not forget that we are talking about a dinosaur weighing about 7 tons. However, in relation to what we were saying about posture, the tail was used to balance the weight of the huge head. Reinforcing this point is the fact that the tail was composed of more than 40 vertebrae.

However, many of his bones were hollow. So his weight would decrease, but his strength wouldn’t.

How fast was the T-Rex?

You ever wondered how fast this T-Rex could reach. We all have in our retina scenes from Jurassic Park where the T.rex runs at an amazing speed.
Does this correspond to reality?

Well, I don’t. According to a 2007 study by the University of Manchester this tyrannosaurid could reach a maximum speed of 29 km per hour.

To reach this conclusion they had to use a supercomputer. This computer had to process all the information about the dinosaur’s bone and muscle structure, and it took a week to do so!

Of course, it wasn’t Usain Bolt, but there’s no doubt that if the day came when a T.rex was chasing you, it would be best if you got wings.

Tyrannosaurus rex and feathers: a feathered dinosaur?

Feathers or no feathers. The reality is that today there is still no certainty. In addition, there is a wide variety of opinions.

Some paleontologists claim they may have had feathers all over their bodies. In fact, in China (in the province of Liaoning), four theropod fossils were discovered that showed signs of having feathers. Among them was the fossil of a Velociraptor.

This finding only reinforces the theory that today’s birds are descended from ancient theropods.

There are other opinions that maintain that instead of all over the body, it is possible that they only had feathers in some parts.

While there are studies that state that there are options that he would have had feathers, although not like the current ones, but protofeathers. The protoplumes are the ancestor of the feathers as we know them today, they had a filamentous structure, like elongated bristles.

One proof would be that the coelurosaurians, the family to which the tyrannosaurids belonged, had this type of plumage.

Tyrannosaurid hot-blooded or not

Cold-blooded: because they are reptiles

Until 1960, dinosaurs were always thought to be cold-blooded because of their association with reptiles.

Also, it seemed impossible that an animal the size of a dinosaur could have hot blood, as that would mean that it would have to eat a huge amount of food.

Another test used to refute the fact that dinosaurs were cold-blooded was the growth marks on their bones, which are similar to those of reptiles.

Neither cold nor hot: mesothermal

A study by the University of New Mexico stays in the middle: neither cold nor hot.

According to study director John Grady, the vast majority of dinosaurs were mesothermic. Their presentation is based on research they did on the growth rate and metabolism of these prehistoric animals.

The faster an animal grows, the more energy and body heat it needs. After crossing data between different animals of similar size, the conclusion was that dinosaurs had an intermediate growth rate. Therefore, the chances that they were mesothermal are very high.


To this day all indications point in this direction.

A scientist at Stony Brook University, Michael D`Emic, reviewed all the data extracted from the University of New Mexico study, dismissing the conclusions Grady had drawn.

According to D`Emic, the New Mexico team did not estimate dinosaur growth rates well because they valued them as growing regularly when they did not. For this paleontologist, they were growing at the same rate as mammals, and therefore, they would have warm blood.

Therefore, everything points to the fact that our Tyrannosaurus was very hot-blooded.

Tyrannosaurus Behavior

Female T.rex or male T.rex: were there female Tyrannosaurus?

It was not clear whether there was sexual dimorphism (significant differences between the two sexes) among the tyrannosaurus.

In fact, some paleontologists have acknowledged that despite the numerous fossils found, very little is known about the sexual traits of dinosaurs.

Everything changed very recently, in March of this year (2016), scientists at North Carolina State University and the North Carolina Museum of Natural Science found a bone marrow from a femur of a Tyrannosaurus rex.

The importance of this finding comes from the fact that in this type of bones only exist in birds that are about to lay their eggs.

This finding is also another step in explaining the evolution of dinosaurs to modern birds.

Not much is known about the life and behavior of the Tyrannosaurus as a group. It is believed that females did live in groups, while males wandered alone.


The process would be as follows. Having the eggs, the female would bury them in the ground (like the turtles do). At birth, T.rex offspring were protected by the group in very wooded or inaccessible areas. At the age of ten, the males separated from the group and began their life alone.

They would only approach the females again when they were in heat.

However, in 2014 there was evidence that it was possible for tyrannosaurids to live in groups.

Three traces of Tyrannosaurus’ footprints were found in Canada, walking in the same direction. Also, because of their size and depth, it could be ruled out that they were from one mother with her two young.

These footprints would be a testament to the fact that the T.R.E.S. could have lived in groups.

How was the copulation of the Tyrannosaurus

As in the previous case, we are dealing with a subject on which there are no certainties.

While there are scientists who see the theory that Tyrannosaurus did have a penis as viable, there are others who defend the hypothesis that it had a “sewer”.

In the opinion of José Carlos García Ramos, scientific director of the Jurassic Museum of Asturias, the reproduction of the Tyrannosaurus must be similar to that of the birds, since they are their most modern relatives.

In this sense, he defends the thesis of a “sewage” reproduction. The cloaca is a cavity that combines the reproductive and urinary functions. For reproduction, the T.rex would join their two sewers, thus injecting the male sperm into the female.

According to the biologist, Olivia Judson, it cannot be said that T.rex did not have a penis. Their opinion is that a group of birds (Palegnathae) do have a penis-like limb. It cannot be seen with the naked eye as it is hidden in the sewer, but it does appear at the time of intercourse.

The growth of this T-Rex

The life expectancy and growth rate of Tyrannosaurus can be determined by the fossils that have been found.

According to what has been established so far, the “ceiling” for the age of these dinosaurs was over 30 years old.

His growth was not continuous during his lifetime. T.rex grows steadily until it reaches the age of 14. Its weight at this point is close to two tons. At that time, its growth is shot up for four years, taking in this period about 3 tons more weight.

By the time they reach 18, however, their growth slows down again. Just like in the beginning.

What did the Tyrannosaurus rex eat?

We already started from the premise that the jaw of this T-Rex measured about one meter. With such a jaw it is no wonder that the strength of his bite was impressive. It is estimated that it was capable of exerting a force of about 4 tons on average. This implies that a single bite of the T.rex would have been able to pull out 225 kilos of meat.

Incredible as it may seem, it’s not the most potent bite dinosaur. In 2009, a fossil of Pliosaurus funkei was found. It is estimated that it may have had a bite capacity four times greater.

Was it the T.rex scavenger or not?

Another great debate about our tyrannosaurus. We present the different points of view:

He was just a scavenger:

  1. He had little ability to run compared to other dinosaurs.
  2. Their arms were not long enough to hold their prey.

The defenders of Tyrannosaurus rex as a hunter manifest:

  1. There is evidence of attacks by Tyrannosaurs on other dinosaurs. For example, the tooth of a T.rex was found embedded in the tail of an Edmontosaurus.
  2. He had a vision and a wonderful sense of smell, ideal for a hunter.
  3. It would be very difficult for Tyrannosaurs to survive on carrion alone, as it would be difficult for there to be a large enough amount to feed a dinosaur of such size.

Many paleontologists suggest that the Tyrannosaurus was both a hunter and a scavenger at the same time. It would not be the only predator that maintains that position, the lions themselves are also capable of eating carrion.

T.rex vs T.rex: cannibalism among Tyrannosaurs

There are samples of fossils in which you can see marks of the attack of one Tyrannosaurus against another Tyrannosaurus. These findings raised the question of whether the tyrannosaurids were cannibals.

Despite these indications, it is not believed that the Tyrannosaurus attacked each other.

The marks found may be due to the fact that the Tyrannosaurus ate the remains of the body of a specimen of the same species. This hypothesis is maintained since the marks come from parts of the body that are not very fleshy, which leads us to believe that the areas with the most meat had already been eaten by another predator.

T.rex Vs Spinosaurus: the battle between two giants

In Jurassic Park, you can see a scene where a Spinosaurus fights a Tyrannosaurus rex. In fact, this dinosaur (very famous for the crest of his back) was victorious in the battle.


At first, the Tyrannosaurus bites the neck of this other theropod with its jaws, although it manages to release itself. At that moment, the Spinosaurus takes the opportunity to grab the T.rex’s neck with his powerful jaw and break it.

The film made this struggle famous, but the reality is that it would never have been able to produce. These two dinosaurs did not inhabit at the same time.

Whereas the tyrannosaurid lived in the Maastricht period, the Spinosaurus lived in the Cenomanian period. We’re talking about a difference of about 40 million years.

Furthermore, they could not have been found either because Tyrannosaurus rex resided in North America, while Spinosaurus lived in Africa.

Even if it would have been formidable to think of a fight between the two (as long as one was safe) it is very unlikely that the Spinosaurus could have beaten the Tyrannosaurus rex. Yes, it was bigger but much less powerful and heavy than the T-Rex. Not to mention that the Spinosaurus’ jaw could never have competed for size or strength.

For a time it was considered that the tyrannosaurid’s saliva might have been infectious, thus providing him with another weapon against his rivals.
This theory was established by William Abler when he discovered some spaces in his teeth where he could retain rotten flesh. This would have meant that every time the Tyrannosaurus had bitten someone, a legion of bacteria would also have attacked their opponent.

This hypothesis was rejected by the paleontologist, Jack Horner. Abler set the Komodo dragon as a precedent for his theory, but Horner was able to prove that the two creatures could not be compared because they had some differences that invalidated that conjecture.

King Kong vs T.rex: Fighting on the screens

One of the most monstrous battles you can imagine is the one between the burly King Kong and our dinosaur king. Well, believe it or not, this big fight did take place: on the big screen.

In both the 1933 film and the 2005 remake, the giant gorilla is up against a T.rex. In particular, he fights against three and although he is victorious (he is still the main character) he is not doing well.

One on one, King Kong has more options because of its speed and intelligence. The Tyrannosaurus would have had a hard time being able to catch him in his jaws, although if he did bite him, with the power of his jaws he might be able to break his arm. However, it would be necessary to assess how long the Tyrannosaurus would be able to withstand the gorilla’s punches.

An autopsy to a Tyrannosaurus rex

We close this article with one of the most amazing questions about this impressive prehistoric animal.

In 2015, a group of paleontologists and veterinarians performed an autopsy on a life-size reproduction of a Tyrannosaurus rex. To make it the same as a real autopsy, the reproduction included all the internal organs of the tyrannosaurid: bones, muscles, organs, tendons… and to make it even more realistic, the blood was also included.

In fact, the reproduction is based on the remains of “Sue”, the Tyrannosaurus whose most complete skeleton was found.

As if a group of CSI had found a Tyrannosaurus who had just died. Its nearly 13 meters long was lying on a huge autopsy table, ready to show the world one of the most amazing anatomies in history.

Everything was done in front of the cameras because this “operation” was done for a National Geographic special (T.rex Autopsy).

The surprises did not end there since at the time of the autopsy it could be discovered that this “Tyrannosauria” was pregnant. So that all the spectators could see the egg in the oviduct. But like good CSIs, they also opened his stomach. The recreation was so perfect that they even prepared the stomach to expel the corresponding gases.

And what do you think the scientists used to open up the T.R.E., a scalpel? Maybe one of his toenails could have worked.

To open the body of the Tyrannosaurus they had to use a chainsaw, no wonder we are talking about the king of the dinosaurs.

As you can see, it’s no wonder the legend that accompanies this dinosaur. From start to finish, we have not stopped seeing that it was a creature as terrifying as it was fantastic. We are not talking about just any dinosaur, but about the king of tyrannical lizards: the Tyrannosaurus rex.