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Description
Tyrannosaurus rex
For over a century, one creature from the Mesozoic has captivated the hearts and minds of people across the planet. One of the largest land carnivores that ever walked the planet, an icon of museum halls across the globe and made famous in countless books, movies, video games, and comics. The King of Dinosaurs, the Tyrant Lizard King, Tyrannosaurus rex.

History of Discovery:

The first teeth of this dinosaur were discovered in the 1870s by paleontologist John Bell Hatcher. They were at first attributed to either a large mammal or an ornithomimid. In 1892, Edward Drinker Cope described a vertebral fragment of Tyrannosaurus, however, he thought it was a ceratopsian dinosaur and not a massive theropod. "Manospondylus gigas" was the name he gave to it; the name literally means “Giant Porous Vertebra” after the porous structure of the vertebra.
The first true skeleton of T.rex was discovered in 1900 by American Museum of Natural History assistant curator, Barnum Brown in Eastern Wyoming. Only 10% of the skeleton was preserved consisting of a fragmentary skull, a partial ribcage, and most of the leg bones. Despite its fragmentary nature, it was clear that this dinosaur was different from other carnivorous dinosaurs from North America. At the time, the largest carnivorous dinosaur known was Allosaurus, but this dinosaur was bigger than any Allosaurus. Brown sent the remains back to New York where President Henry Fairfield Osborn named them. He concocted a name that would be the most iconic in all of the binomial nomenclature, Tyrannosaurus rex. Deriving the generic name from the Greek, “τύραννος” meaning “Tyrant” and “σαῦρος” meaning lizard and the species name from the Latin word, “rex” meaning king. The Tyrant Lizard King, arguably the most famous and recognizable name in the animal kingdom.
A few pages later, Albertosaurus, a cousin of T.rex was named in the paper. The name for this Tyrannosaur comes from Alberta which had just had provincial status approved. Since this paper made a new family of carnivorous dinosaurs, had Osborn chosen to describe Albertosaurus first, the entire family would have been called Albertosaurs because of rules that govern how a new family/species is named. Since Tyrannosaurus was named first, and thus, Tyrannosaurs is how paleontologists describe this whole family.
In the years following the naming, Brown unearthed more Tyrannosaurus, including a new Tyrannosaurus rex, AMNH 5027 which is still on display at the American Museum of Natural History in New York City. Originally, Osborn planned an iconic exhibit it with the holotype with the two dinosaurs locked in mortal combat, but the technical requirements to mount it were too great and thus, he settled on a standard Godzilla-like pose in the museum hall. For years, it would be the only T.rex mount until Brown donated the holotype (original fossil) to the Carnegie Museum where it would be in a similar pose for decades. However, the story of the various skeletons and their discoveries in the following years of the 20th century is a story for another day.

Evolution:

Tyrannosaurus’ evolutionary history is somewhat interesting. At first, it was believed that it split off from the legendary Carnosaurs. Animals like Allosaurus and Acrocanthosaurus with their massive skulls and serrated teeth. With further discoveries in the intervening years, that view is now believed to be incorrect. Tyrannosaurus and its kin are a group within the clade Coelurosauria, which include dromaeosaurs, ornithomimids, compsognathids, troodontids, oviraptorosaurs, therizinosaurs and of course, modern birds.

Tyrannosaurs at first were smaller dinosaurs known as Proceratosauridae, which were part of a larger group known as tyrannosauroids (this included more derived tyrannosaurs, but also more basal members). Animals like Guanlong and Proceratosaurus. Animals with longer arms, covered in downy feathers, and sported unique head crests. It would not be until the Early Cretaceous around 125,000,000 years ago that the first giant predators would arise. Yutyrannus were the last and largest of the proceratosauridae tyrannosauroids, and the first apex predators that arrived on the scene. However, they were mainly limited to Asia. Understandable since the carnosaurs were still prevalent across the globe at this time, and they had yet to reach their apex in terms of size. However, by around 90,000,000 years ago, the gigantic carnosaurs vanished from the planet. Leaving an ecological niche that needed to be filled. In the southern hemisphere, Abelisaurs dominated the more open environments, whereas in the northern hemisphere true tyrannosaurs arose some 85-80,000,000 years ago.
Early on it was thought that dinosaurs like Gorgosaurus and Daspletosaurus would eventually give rise to the iconic T.rex. Makes sense since they were both from North America and they evolved from a North American ancestor. However, many paleontologists now believe that the aforementioned animals were actually in separate subfamilies of tyrannosaurs.
Paleontologist Steve Brusatte has proposed that approximately 80,000,000 years ago, there was a faunal exchange between Asia and North America. A Tyrannosaur similar to Lythronax made its way into Asia. There, they would diversify into families, the narrow snouted and smaller Alioramini and the more iconic Tyrannosaurini. With animals like Tarbosaurus and Zhuchengtyrannus arising in Asia. Approximately 71-69,000,000 years ago, there was another faunal interchange back into America. There, Tyrannosaurus rex would arise and for the last 2,000,000 years of the Mesozoic, it would become the largest carnivorous dinosaur the world has ever seen.

Description:

Tyrannosaurus was among the largest carnivorous animals that ever walked the planet. The largest specimens are over 40ft long and 12-13ft tall at the hip. While some carnosaurs like Giganotosaurus and Carcharodontosaurus, and the massive Spinosaurus come close to or even surpassed T.rex in terms of dimensions, mass-wise, they are almost always outclassed.

The largest T.rex skeleton, FMNH PR 2081, AKA Sue, has estimates of around 10 tons in weight. However, estimates as high as 15 or even 17 tons in weight have been proposed, but these are believed to be over-estimates.
They were heavy-set theropods, with bigger, stouter, and all-around more robust bodies than other theropods. A barrel torso, tapering into a thinner waste. A long stiff tail helped balance the massive head and bulk of the torso at the front of its body.

The legs of Tyrannosaurus were massive and robust. The center foot bone had something common with other maniraptoran theropods like the Ornithomimids. In that it had an arctometatarsalian condition. The center foot bone was crushed between the two adjacent foot bones. This enabled them to regain energy more efficiently than other dinosaurs. In 2020, evidence indicated that Tyrannosaurus was a very efficient walker, reaching walking speeds of 2-3mph. Moreover, recent research indicates that the limbs of T.rex, despite being robust and powerful, were unable to propel it faster than ~16mph at its fastest and 11mph on avg. Even then, it couldn't run. Studies into the limbs indicate that if it tried to run, it'd shatter its limbs due to skeletal loads on the hindlimbs.
The largest T.rex skull that has been found, Sue is 4ft in length. With keratinous sheaths atop the skull and down the snout. Furthermore, they had forward-facing eyes. Meaning Tyrannosaurus had binocular vision. This enabled it to have both better vision as well as perceive depth better than other theropod dinosaurs.
Arguably the most famous feature would be the teeth. The massive jaws of T.rex were equipped with thick, rigid teeth with serrations both front and rear. Unique to T.rex and other Tyrannosaurs is that they actually have incisors, at the front of their jaws. The serrations were only on the back of the teeth and trace fossil evidence found in Asia from the related Tarbosaurus is that they used the teeth to gently scrape the meat off the bone.
The bite force has been estimated to be around 12,800lbf. The most powerful bite of any terrestrial animal living or dead. Its bite was capable of crushing right through flesh and bone.

Arguably, aside from its head, the most stand-out feature would be its arms. Its small didactyl hands are tipped with two claws. Slightly longer than the avg. human arm, the forelimbs were small. With some paleontologists theorizing that they were vestigial. However, recent studies of Tyrannosaurus arms have found evidence of muscle scarring on the bones, suggesting that while they were small, they were actually quite strong. Osborn proposed that they could have been used for grappling their mates while copulating. A theory that makes sense, considering it would have been hard for dinosaurs who weighed more than elephants to mate without the male having a grip on his mate. Other suggestions include grappling with prey. At first it may seem weird, but a smaller arm could mean it had less surface area to target and may have made the two claws on their fingers better at cutting through flesh. Though a lot of paleontologists have countered this theory given that they would have needed just to get close and use their head instead of their tiny arms. The final theory is the arms were utilized to help themselves get off the ground when it went asleep or was resting. A 2021 description of a trackway supports this as it shows what looks like a Tyrannosaur standing up using its elbows to push up from the ground.

Scales or Feathers?:

In 2012, Yutyrannus, a distant cousin to T.rex was found in China. This lit off a buzz of speculation about the status of feathers in large-bodied theropods, including Tyrannosaurus. Paleoart from this time shows T.rex sporting at least some feathering. In 2017, a study was conducted on documented skin impressions of tyrannosaurs from Tarbosaurus, Gorgosaurus, Albertosaurus and of course, T.rex. What they found was no evidence of feathering on any of the dinosaurs. Using phylogenetics, it’s believed that in true tyrannosaurs, feathering was not a feature on their bodies.

In T.rex specifically, it makes sense. With larger animals, if they don’t need feathers for insulation, why would they need to keep it? This is seen in modern mammals like the Elephant and Rhino.

The scales themselves varied from region to region. Though for the most part, the closest analogue would be the reticula that are seen on birds’ feet.

There is a trend in paleoart that shows juvenile large-bodied theropods having feathers and losing them as they age. This could be possible, as it’s seen in modern-day Asian Elephants, with some juveniles having masses of hair, and eventually nearly losing it altogether. However, it should be noted that this is completely speculative, and has not been proven.

Habitat:

Tyrannosaurus fossils have been found all over America. From Canada to Texas, these animals had a vast range across the western United States. It’s possible they could have made it to the eastern parts of America, however, rocks east of the Mississippi River that are Mesozoic aged are quite rare and barely any match the age of Tyrannosaurus.

Most fossils of T.rex have been found in Montana which is part of the Hell Creek Formation. Environmentally, it resembled a tropical to subtropical floodplain environment, similar to parts of Louisiana today. However, there were conifer forests dotted around the environment with plants like Monkey Puzzle or Araucaria trees and Sequoia trees as well. Though some more recognizable plants like pines and oaks have been discovered as well. Plains were present in the environment as well. Although grass evolved around the time of T.rex’s reign, it wasn’t nearly as widespread as it is today. The plains would have been covered in Horsetail and Ferns.

Hell Creek was the home of countless animals as well. A myriad of birds have been found in the environment. Mammals like the ancient marsupial Didelphodon and the basal primate Purgatorius lived in the region too. A couple of crocodilian species have been found here too often being the size of an American Alligator. Reptiles like snakes and even lizards related to monitors have been found in the environment as well. A handful of Pterosaur fossils have been found here, with a recently undescribed species of azhdarchid from Hell Creek.
However, the most famous residents aside from T.rex were the dinosaurs. The most common herbivorous dinosaur was the famous "3-horned face", Triceratops followed by the large hadrosaur Edmontosaurus. Both were likely prey to Tyrannosaurus itself. The club-tailed Ankylosaurus was also found here, but relatively rare. Ornithomimus and Struthiomimus which were lithe and fast bird-like dinosaurs and shared the environment with T.rex. Furthermore, there were also more obscure dinosaurs like the small ornithopod Thescelosaurus and a ceratopsian Leptoceratops, a ceratopsian that resembled more primitive forms of these horned dinosaurs. Both of these creatures were just as rare as Ankylosaurus. Troodontids and Dromaeosaurs have also been found in Hell Creek likely filling the niche of small predators.
Strangely enough, Tyrannosaurus was the only large carnivore in the region. Compared to Tyrannosaurus, the next largest carnivore is Dakotaraptor. A relatively large raptor which weighed in at only 600-750lbs, but compared to T.rex, it’s like comparing a jackal to a lion. The most commonly accepted theory is that juvenile T.rex filled the niche of medium-to-large carnivore niche. With a lighter build than their adult counterparts, they were far better oriented to chase down prey. However, at the same time, it could be possible that other theropods in the medium carnivore size-range filled it along with juvenile Tyrannosaurs. After all, Dakotaraptor was discovered in 2015, so there could be other carnivores that lived alongside T.rex. However, as of now, T.rex ruled the West.

Social Behavior:

Social behavior in tyrannosaurs is something that is hotly debated. Whether or not tyrannosaurs lived in packs or reared their young, while popular has never been officially proven. Furthermore, there’s evidence of related tyrannosaurs, Albertosaurus and Tarbosaurus found together. A further undescribed find from 2011 in South Dakota had 3 fragmentary specimens of T.rex found together.
Pack hunting could be a possible counter to hunting dinosaurs like Triceratops, Ankylosaurus, and in parts of New Mexico and Texas, the giant sauropod Alamosaurus.
Paleontologist Dr.Philip Currie has been a massive proponent of pack behavior in tyrannosaurs. Especially an Albertosaurus bone bed he found with his team in 1998.
However, this is not viewed to be evidence to most of the paleontological community. Given that for one, it hasn’t been peer-reviewed, and secondly, it could have been a group of Albertosaurs washed together after a flash flood. The same could be the case with other tyrannosaurs found together.
The only unambiguous piece of evidence that supports social behavior is a trackway with of several tyrannosaurs moving together in the same direction. Though whether or not this is a family group is uncertain. It could be just 3 tyrannosaurs tolerating each other as they walk forward. Even animals that are hostile to each other like the Komodo Dragon tolerate each other when they move forward.

Without observing living animals, the social behavior of this massive carnivore will always be up to speculation.

Cannibalism:

Cannibalism is something that is ubiquitous in almost every reptilian/archosaurian animal. It's not that farfetched to believe that T.rex engaged in this behavior too. Various fossil finds from New Mexico suggest cannibalism was present in tyrannosaurs, describing bites on various bones of tyrannosaurs from various ages. Moreover, a 2010 study found evidence of tooth marks on the humerus and metatarsals of various Tyrannosaurus fossils. It was seen as opportunistic cannibalism. In that the dinosaur was dead when the other individual came upon it. Paleontologists arrived at this conclusion given the fact it would've been hard to take bites at the foot in combat.
Furthermore, countless skull bones of various theropods show evidence of face-biting behavior. It's absolutely plausible that these fights could have led to death and the victor would enjoy a free meal after defending its territory/right to mate.

Scavenger or Hunter?:

A question that has surfaced in recent decades was whether or not T.rex was a predator or a scavenger. This question was largely brought up by the now infamous Paleontologist Dr. Jack Horner. It should be noted that he or any of his colleagues (who support his theory) have never formally published this theory in any journal and backed it up. Mainly Dr.Horner advocates this theory because he uses it as a "textbook example" as to how scientists should not arrive at any preconceived conclusions. Furthermore, he has stated he does not like the dinosaur.

Horner points that T.rex had a powerful sense of smell due to studies of their brain which have massive olfactory bulbs. The sense of smell would have enabled it to track down carcasses of hadrosaurs and ceratopsians which could have been plentiful during periods of drought.
Horner also pointed out the size of the arms. He stated that animals needed to grab their prey to be successful predators. With an arm the size of a human, how could it have hunted? Even more evidence came when paleontologists found that it couldn't run (as previously mentioned). How could they catch prey if they couldn't run them down? On paper and to the average laymen, it may make sense however, on further examination, it starts to fall apart.

T.rex had forward-facing eyes. This eye orientation gave it binocular vision. A trait necessary for predators since binocular vision allows them to perceive depth better than other predatory dinosaurs. Using restorations of the eyes coupled with the region of the brain that includes sight, suggests T.rex would have slightly better eyesight than a hawk. So, IF Tyrannosaurus was a pure scavenger, WHY would it have retained both binocular vision and a well-developed sense of sight if it never needed to hunt?
Grabbing prey is also not a prerequisite to being a predator. Animals like wolves or hyenas don't utilize their forelimbs in any manner when bringing down prey. Relying mainly on their jaws to do damage to their quarry. The same can be said for relatives of Tyrannosaurus, the birds. Birds of prey use their talons and beaks to catch and kill prey. Furthermore, the South American seriema use their beaks to kill their prey by slamming it into the ground and then ripping it apart by restraining it with their feet. With T.rex having such a massive skull and jaws, using their arms to catch prey (as discussed previously), while possible, would have been unnecessary as they could have just used their skull equipped with powerful jaws and robust teeth to kill prey.
The sense of smell being used to sniff down carcasses has been countered by Dr.Thomas Holtz. Holtz pointed out that dinosaurs like Dromaeosaurs have equally large olfactory processes. Thus, if Tyrannosaurus was a scavenger, why not lump dromaeosaurs like Velociraptor or Utahraptor in there as well?
As for running down prey, it's important to remember, T.rex didn't need to run down lightly built prey like ostriches or horses. It needed to hunt hadrosaurid and ceratopsian dinosaurs. It needed to be as fast or only slightly faster than the prey that it had to catch. Thus, it being unable to run is likely not a factor in it being a predator or not.

Above all else, there’s evidence of failed predation in its contemporary dinosaurs. Fossils of Triceratops have been found which shows re-healed wounds on frills and horns. In one case, Tyrannosaurus bit down on the frill, raked it, and got fragments of bone ripped off. A paper from 2013 showed evidence of a Tyrannosaurus tooth tip embedded in the bone of an Edmontosaurus tail vertebra. The Tyrannosaurus bit down on the tail broke off the tooth and the hadrosaur lived to have new tissue grow around it. How else could that tooth tip have gotten there if not the T.rex chased the Hadrosaur, bit into the vertebra and it fled?

The bottom line is, Tyrannosaurus was most like both a scavenger and hunter. Not surprising at all considering many predators will not pass up a free meal if it's available to them.

Extinction:

66,000,000 Years ago, the reign of the dinosaurs came to an end. An Asteroid 6-7 miles wide impacted into the Gulf of Mexico and marked the end of these magnificent reptiles. Tyrannosaurus was among the casualties of this mass extinction event. The impact would have kicked up the dust and debris which blocked out the sun preventing plant growth. This marked the end of the massive herbivorous dinosaurs and T.rex’s main food source.

With the prey gone, the population diminished rapidly, and ultimately, marked the end of T.rex’s reign and the end of the non-avian dinosaurs. Today, only T.rex’s distant cousins, the birds still persist to today. It wouldn’t be for another 66,000,000 years that this iconic dinosaur would be unearthed and capture the imagination of people around the world.

Long live the Tyrant Lizard King.
___________________________________________________________________________________________

Happy New Year guys!!! Thought I’d ring it in with the most iconic Dinosaur that ever lived. I had actually originally posted this profile in April with a far shorter description, however, because it used arvalis Saurian skin without permission, I had to wait until my friend Tyranachu finished remaking it. And hot damn, he did a great job.

At FIRST I thought about posing the dinosaur with two T.rexes fighting over a carcass. Similar to Carnegie Museum/The Original Planned Mount at the AMNH. However, having looked through some pictures, I decided to depict a family of T.rexes vanquishing a rival.

Furthermore, I’ve revamped how my profiles will go. Putting down various sections in the profiles that I think are up to snuff. I likely will rewrite a lot of the animals’ profiles in the coming days with this new system.

Now, I could have gone into a ton more detail about things like, Tyrannosaurus’ growth stages, its appearance in the Jurassic Park Franchise, the various specimens, etc. However, that is stuff for future profiles, fact sheets, etc. that I have planned down the line.

Interesting fact, even in the 2000s, the Carnegie Museum’s (Holotype) still had the outdated Kangaroo pose.
Source: I had a friend from my Pre-K class who went there, and they had a pic of it from 2003 on the wall. As well as:
Carnegie's Famed Dinosaurs Get a Makeover : NPR
It wasn’t unveiled till ~2007.

Speaking of makeover, I had to revamp a lot of these guys in order to get them up to snuff to my standards.

Huge thanks to randomdinos Paleonerd01 and Franoys for their skeletal diagrams. I had to widen the torso for the adults, gave the skull some modifications for the base model, and I had to remake some of the skulls. What do I mean?
The adults in the pic are more different than at first glance: The one in the foreground is based on my state’s most iconic T.rex Sue. The one that’s dead is actually based on AMNH 5027 (Rexy). Finally, the one in the background is based on MOR 008 (Custer’s Rex).

Here’s a pic comparing them:
i.imgur.com/Dhmcw0l.jpg

Will this be in PMP? Obviously. This is the star of Episode 6, and I’ve got some great scenes planned out for this icon. So glad to finally put this profile out and hope you guys have a great new year! Episode 3 will be done in a few more days. I accidentally saved over one of the paddocks which I had to rebuild (just finished) and I also have to get the promo shots ready for Episode 4.

In the meantime, hope you guys have a great New Year, and I’m looking forward to seeing where my art and stories go this year.
Original Mesh and Skin by Tyranachu, mesh modified by me:
Tyrannosaurus (Tyranachu) | ZT2 Download Library Wiki | Fandom

Description
Tyrannosaurus rex
For over a century, one creature from the Mesozoic has captivated the hearts and minds of people across the planet. One of the largest land carnivores that ever walked the planet, an icon of museum halls across the globe and made famous in countless books, movies, video games, and comics. The King of Dinosaurs, the Tyrant Lizard King, Tyrannosaurus rex.

History of Discovery:

The first teeth of this dinosaur were discovered in the 1870s by paleontologist John Bell Hatcher. They were at first attributed to either a large mammal or an ornithomimid. In 1892, Edward Drinker Cope described a vertebral fragment of Tyrannosaurus, however, he thought it was a ceratopsian dinosaur and not a massive theropod. "Manospondylus gigas" was the name he gave to it; the name literally means “Giant Porous Vertebra” after the porous structure of the vertebra.
The first true skeleton of T.rex was discovered in 1900 by American Museum of Natural History assistant curator, Barnum Brown in Eastern Wyoming. Only 10% of the skeleton was preserved consisting of a fragmentary skull, a partial ribcage, and most of the leg bones. Despite its fragmentary nature, it was clear that this dinosaur was different from other carnivorous dinosaurs from North America. At the time, the largest carnivorous dinosaur known was Allosaurus, but this dinosaur was bigger than any Allosaurus. Brown sent the remains back to New York where President Henry Fairfield Osborn named them. He concocted a name that would be the most iconic in all of the binomial nomenclature, Tyrannosaurus rex. Deriving the generic name from the Greek, “τύραννος” meaning “Tyrant” and “σαῦρος” meaning lizard and the species name from the Latin word, “rex” meaning king. The Tyrant Lizard King, arguably the most famous and recognizable name in the animal kingdom.
A few pages later, Albertosaurus, a cousin of T.rex was named in the paper. The name for this Tyrannosaur comes from Alberta which had just had provincial status approved. Since this paper made a new family of carnivorous dinosaurs, had Osborn chosen to describe Albertosaurus first, the entire family would have been called Albertosaurs because of rules that govern how a new family/species is named. Since Tyrannosaurus was named first, and thus, Tyrannosaurs is how paleontologists describe this whole family.
In the years following the naming, Brown unearthed more Tyrannosaurus, including a new Tyrannosaurus rex, AMNH 5027 which is still on display at the American Museum of Natural History in New York City. Originally, Osborn planned an iconic exhibit it with the holotype with the two dinosaurs locked in mortal combat, but the technical requirements to mount it were too great and thus, he settled on a standard Godzilla-like pose in the museum hall. For years, it would be the only T.rex mount until Brown donated the holotype (original fossil) to the Carnegie Museum where it would be in a similar pose for decades. However, the story of the various skeletons and their discoveries in the following years of the 20th century is a story for another day.

Evolution:

Tyrannosaurus’ evolutionary history is somewhat interesting. At first, it was believed that it split off from the legendary Carnosaurs. Animals like Allosaurus and Acrocanthosaurus with their massive skulls and serrated teeth. With further discoveries in the intervening years, that view is now believed to be incorrect. Tyrannosaurus and its kin are a group within the clade Coelurosauria, which include dromaeosaurs, ornithomimids, compsognathids, troodontids, oviraptorosaurs, therizinosaurs and of course, modern birds.

Tyrannosaurs at first were smaller dinosaurs known as Proceratosauridae, which were part of a larger group known as tyrannosauroids (this included more derived tyrannosaurs, but also more basal members). Animals like Guanlong and Proceratosaurus. Animals with longer arms, covered in downy feathers, and sported unique head crests. It would not be until the Early Cretaceous around 125,000,000 years ago that the first giant predators would arise. Yutyrannus were the last and largest of the proceratosauridae tyrannosauroids, and the first apex predators that arrived on the scene. However, they were mainly limited to Asia. Understandable since the carnosaurs were still prevalent across the globe at this time, and they had yet to reach their apex in terms of size. However, by around 90,000,000 years ago, the gigantic carnosaurs vanished from the planet. Leaving an ecological niche that needed to be filled. In the southern hemisphere, Abelisaurs dominated the more open environments, whereas in the northern hemisphere true tyrannosaurs arose some 85-80,000,000 years ago.
Early on it was thought that dinosaurs like Gorgosaurus and Daspletosaurus would eventually give rise to the iconic T.rex. Makes sense since they were both from North America and they evolved from a North American ancestor. However, many paleontologists now believe that the aforementioned animals were actually in separate subfamilies of tyrannosaurs.
Paleontologist Steve Brusatte has proposed that approximately 80,000,000 years ago, there was a faunal exchange between Asia and North America. A Tyrannosaur similar to Lythronax made its way into Asia. There, they would diversify into families, the narrow snouted and smaller Alioramini and the more iconic Tyrannosaurini. With animals like Tarbosaurus and Zhuchengtyrannus arising in Asia. Approximately 71-69,000,000 years ago, there was another faunal interchange back into America. There, Tyrannosaurus rex would arise and for the last 2,000,000 years of the Mesozoic, it would become the largest carnivorous dinosaur the world has ever seen.

Description:

Tyrannosaurus was among the largest carnivorous animals that ever walked the planet. The largest specimens are over 40ft long and 12-13ft tall at the hip. While some carnosaurs like Giganotosaurus and Carcharodontosaurus, and the massive Spinosaurus come close to or even surpassed T.rex in terms of dimensions, mass-wise, they are almost always outclassed.

The largest T.rex skeleton, FMNH PR 2081, AKA Sue, has estimates of around 10 tons in weight. However, estimates as high as 15 or even 17 tons in weight have been proposed, but these are believed to be over-estimates.
They were heavy-set theropods, with bigger, stouter, and all-around more robust bodies than other theropods. A barrel torso, tapering into a thinner waste. A long stiff tail helped balance the massive head and bulk of the torso at the front of its body.

The legs of Tyrannosaurus were massive and robust. The center foot bone had something common with other maniraptoran theropods like the Ornithomimids. In that it had an arctometatarsalian condition. The center foot bone was crushed between the two adjacent foot bones. This enabled them to regain energy more efficiently than other dinosaurs. In 2020, evidence indicated that Tyrannosaurus was a very efficient walker, reaching walking speeds of 2-3mph. Moreover, recent research indicates that the limbs of T.rex, despite being robust and powerful, were unable to propel it faster than ~16mph at its fastest and 11mph on avg. Even then, it couldn't run. Studies into the limbs indicate that if it tried to run, it'd shatter its limbs due to skeletal loads on the hindlimbs.
The largest T.rex skull that has been found, Sue is 4ft in length. With keratinous sheaths atop the skull and down the snout. Furthermore, they had forward-facing eyes. Meaning Tyrannosaurus had binocular vision. This enabled it to have both better vision as well as perceive depth better than other theropod dinosaurs.
Arguably the most famous feature would be the teeth. The massive jaws of T.rex were equipped with thick, rigid teeth with serrations both front and rear. Unique to T.rex and other Tyrannosaurs is that they actually have incisors, at the front of their jaws. The serrations were only on the back of the teeth and trace fossil evidence found in Asia from the related Tarbosaurus is that they used the teeth to gently scrape the meat off the bone.
The bite force has been estimated to be around 12,800lbf. The most powerful bite of any terrestrial animal living or dead. Its bite was capable of crushing right through flesh and bone.

Arguably, aside from its head, the most stand-out feature would be its arms. Its small didactyl hands are tipped with two claws. Slightly longer than the avg. human arm, the forelimbs were small. With some paleontologists theorizing that they were vestigial. However, recent studies of Tyrannosaurus arms have found evidence of muscle scarring on the bones, suggesting that while they were small, they were actually quite strong. Osborn proposed that they could have been used for grappling their mates while copulating. A theory that makes sense, considering it would have been hard for dinosaurs who weighed more than elephants to mate without the male having a grip on his mate. Other suggestions include grappling with prey. At first it may seem weird, but a smaller arm could mean it had less surface area to target and may have made the two claws on their fingers better at cutting through flesh. Though a lot of paleontologists have countered this theory given that they would have needed just to get close and use their head instead of their tiny arms. The final theory is the arms were utilized to help themselves get off the ground when it went asleep or was resting. A 2021 description of a trackway supports this as it shows what looks like a Tyrannosaur standing up using its elbows to push up from the ground.

Scales or Feathers?:

In 2012, Yutyrannus, a distant cousin to T.rex was found in China. This lit off a buzz of speculation about the status of feathers in large-bodied theropods, including Tyrannosaurus. Paleoart from this time shows T.rex sporting at least some feathering. In 2017, a study was conducted on documented skin impressions of tyrannosaurs from Tarbosaurus, Gorgosaurus, Albertosaurus and of course, T.rex. What they found was no evidence of feathering on any of the dinosaurs. Using phylogenetics, it’s believed that in true tyrannosaurs, feathering was not a feature on their bodies.

In T.rex specifically, it makes sense. With larger animals, if they don’t need feathers for insulation, why would they need to keep it? This is seen in modern mammals like the Elephant and Rhino.

The scales themselves varied from region to region. Though for the most part, the closest analogue would be the reticula that are seen on birds’ feet.

There is a trend in paleoart that shows juvenile large-bodied theropods having feathers and losing them as they age. This could be possible, as it’s seen in modern-day Asian Elephants, with some juveniles having masses of hair, and eventually nearly losing it altogether. However, it should be noted that this is completely speculative, and has not been proven.

Habitat:

Tyrannosaurus fossils have been found all over America. From Canada to Texas, these animals had a vast range across the western United States. It’s possible they could have made it to the eastern parts of America, however, rocks east of the Mississippi River that are Mesozoic aged are quite rare and barely any match the age of Tyrannosaurus.

Most fossils of T.rex have been found in Montana which is part of the Hell Creek Formation. Environmentally, it resembled a tropical to subtropical floodplain environment, similar to parts of Louisiana today. However, there were conifer forests dotted around the environment with plants like Monkey Puzzle or Araucaria trees and Sequoia trees as well. Though some more recognizable plants like pines and oaks have been discovered as well. Plains were present in the environment as well. Although grass evolved around the time of T.rex’s reign, it wasn’t nearly as widespread as it is today. The plains would have been covered in Horsetail and Ferns.

Hell Creek was the home of countless animals as well. A myriad of birds have been found in the environment. Mammals like the ancient marsupial Didelphodon and the basal primate Purgatorius lived in the region too. A couple of crocodilian species have been found here too often being the size of an American Alligator. Reptiles like snakes and even lizards related to monitors have been found in the environment as well. A handful of Pterosaur fossils have been found here, with a recently undescribed species of azhdarchid from Hell Creek.
However, the most famous residents aside from T.rex were the dinosaurs. The most common herbivorous dinosaur was the famous "3-horned face", Triceratops followed by the large hadrosaur Edmontosaurus. Both were likely prey to Tyrannosaurus itself. The club-tailed Ankylosaurus was also found here, but relatively rare. Ornithomimus and Struthiomimus which were lithe and fast bird-like dinosaurs and shared the environment with T.rex. Furthermore, there were also more obscure dinosaurs like the small ornithopod Thescelosaurus and a ceratopsian Leptoceratops, a ceratopsian that resembled more primitive forms of these horned dinosaurs. Both of these creatures were just as rare as Ankylosaurus. Troodontids and Dromaeosaurs have also been found in Hell Creek likely filling the niche of small predators.
Strangely enough, Tyrannosaurus was the only large carnivore in the region. Compared to Tyrannosaurus, the next largest carnivore is Dakotaraptor. A relatively large raptor which weighed in at only 600-750lbs, but compared to T.rex, it’s like comparing a jackal to a lion. The most commonly accepted theory is that juvenile T.rex filled the niche of medium-to-large carnivore niche. With a lighter build than their adult counterparts, they were far better oriented to chase down prey. However, at the same time, it could be possible that other theropods in the medium carnivore size-range filled it along with juvenile Tyrannosaurs. After all, Dakotaraptor was discovered in 2015, so there could be other carnivores that lived alongside T.rex. However, as of now, T.rex ruled the West.

Social Behavior:

Social behavior in tyrannosaurs is something that is hotly debated. Whether or not tyrannosaurs lived in packs or reared their young, while popular has never been officially proven. Furthermore, there’s evidence of related tyrannosaurs, Albertosaurus and Tarbosaurus found together. A further undescribed find from 2011 in South Dakota had 3 fragmentary specimens of T.rex found together.
Pack hunting could be a possible counter to hunting dinosaurs like Triceratops, Ankylosaurus, and in parts of New Mexico and Texas, the giant sauropod Alamosaurus.
Paleontologist Dr.Philip Currie has been a massive proponent of pack behavior in tyrannosaurs. Especially an Albertosaurus bone bed he found with his team in 1998.
However, this is not viewed to be evidence to most of the paleontological community. Given that for one, it hasn’t been peer-reviewed, and secondly, it could have been a group of Albertosaurs washed together after a flash flood. The same could be the case with other tyrannosaurs found together.
The only unambiguous piece of evidence that supports social behavior is a trackway with of several tyrannosaurs moving together in the same direction. Though whether or not this is a family group is uncertain. It could be just 3 tyrannosaurs tolerating each other as they walk forward. Even animals that are hostile to each other like the Komodo Dragon tolerate each other when they move forward.

Without observing living animals, the social behavior of this massive carnivore will always be up to speculation.

Cannibalism:

Cannibalism is something that is ubiquitous in almost every reptilian/archosaurian animal. It's not that farfetched to believe that T.rex engaged in this behavior too. Various fossil finds from New Mexico suggest cannibalism was present in tyrannosaurs, describing bites on various bones of tyrannosaurs from various ages. Moreover, a 2010 study found evidence of tooth marks on the humerus and metatarsals of various Tyrannosaurus fossils. It was seen as opportunistic cannibalism. In that the dinosaur was dead when the other individual came upon it. Paleontologists arrived at this conclusion given the fact it would've been hard to take bites at the foot in combat.
Furthermore, countless skull bones of various theropods show evidence of face-biting behavior. It's absolutely plausible that these fights could have led to death and the victor would enjoy a free meal after defending its territory/right to mate.

Scavenger or Hunter?:

A question that has surfaced in recent decades was whether or not T.rex was a predator or a scavenger. This question was largely brought up by the now infamous Paleontologist Dr. Jack Horner. It should be noted that he or any of his colleagues (who support his theory) have never formally published this theory in any journal and backed it up. Mainly Dr.Horner advocates this theory because he uses it as a "textbook example" as to how scientists should not arrive at any preconceived conclusions. Furthermore, he has stated he does not like the dinosaur.

Horner points that T.rex had a powerful sense of smell due to studies of their brain which have massive olfactory bulbs. The sense of smell would have enabled it to track down carcasses of hadrosaurs and ceratopsians which could have been plentiful during periods of drought.
Horner also pointed out the size of the arms. He stated that animals needed to grab their prey to be successful predators. With an arm the size of a human, how could it have hunted? Even more evidence came when paleontologists found that it couldn't run (as previously mentioned). How could they catch prey if they couldn't run them down? On paper and to the average laymen, it may make sense however, on further examination, it starts to fall apart.

T.rex had forward-facing eyes. This eye orientation gave it binocular vision. A trait necessary for predators since binocular vision allows them to perceive depth better than other predatory dinosaurs. Using restorations of the eyes coupled with the region of the brain that includes sight, suggests T.rex would have slightly better eyesight than a hawk. So, IF Tyrannosaurus was a pure scavenger, WHY would it have retained both binocular vision and a well-developed sense of sight if it never needed to hunt?
Grabbing prey is also not a prerequisite to being a predator. Animals like wolves or hyenas don't utilize their forelimbs in any manner when bringing down prey. Relying mainly on their jaws to do damage to their quarry. The same can be said for relatives of Tyrannosaurus, the birds. Birds of prey use their talons and beaks to catch and kill prey. Furthermore, the South American seriema use their beaks to kill their prey by slamming it into the ground and then ripping it apart by restraining it with their feet. With T.rex having such a massive skull and jaws, using their arms to catch prey (as discussed previously), while possible, would have been unnecessary as they could have just used their skull equipped with powerful jaws and robust teeth to kill prey.
The sense of smell being used to sniff down carcasses has been countered by Dr.Thomas Holtz. Holtz pointed out that dinosaurs like Dromaeosaurs have equally large olfactory processes. Thus, if Tyrannosaurus was a scavenger, why not lump dromaeosaurs like Velociraptor or Utahraptor in there as well?
As for running down prey, it's important to remember, T.rex didn't need to run down lightly built prey like ostriches or horses. It needed to hunt hadrosaurid and ceratopsian dinosaurs. It needed to be as fast or only slightly faster than the prey that it had to catch. Thus, it being unable to run is likely not a factor in it being a predator or not.

Above all else, there’s evidence of failed predation in its contemporary dinosaurs. Fossils of Triceratops have been found which shows re-healed wounds on frills and horns. In one case, Tyrannosaurus bit down on the frill, raked it, and got fragments of bone ripped off. A paper from 2013 showed evidence of a Tyrannosaurus tooth tip embedded in the bone of an Edmontosaurus tail vertebra. The Tyrannosaurus bit down on the tail broke off the tooth and the hadrosaur lived to have new tissue grow around it. How else could that tooth tip have gotten there if not the T.rex chased the Hadrosaur, bit into the vertebra and it fled?

The bottom line is, Tyrannosaurus was most like both a scavenger and hunter. Not surprising at all considering many predators will not pass up a free meal if it's available to them.

Extinction:

66,000,000 Years ago, the reign of the dinosaurs came to an end. An Asteroid 6-7 miles wide impacted into the Gulf of Mexico and marked the end of these magnificent reptiles. Tyrannosaurus was among the casualties of this mass extinction event. The impact would have kicked up the dust and debris which blocked out the sun preventing plant growth. This marked the end of the massive herbivorous dinosaurs and T.rex’s main food source.

With the prey gone, the population diminished rapidly, and ultimately, marked the end of T.rex’s reign and the end of the non-avian dinosaurs. Today, only T.rex’s distant cousins, the birds still persist to today. It wouldn’t be for another 66,000,000 years that this iconic dinosaur would be unearthed and capture the imagination of people around the world.

Long live the Tyrant Lizard King.
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Happy New Year guys!!! Thought I’d ring it in with the most iconic Dinosaur that ever lived. I had actually originally posted this profile in April with a far shorter description, however, because it used arvalis Saurian skin without permission, I had to wait until my friend Tyranachu finished remaking it. And hot damn, he did a great job.

At FIRST I thought about posing the dinosaur with two T.rexes fighting over a carcass. Similar to Carnegie Museum/The Original Planned Mount at the AMNH. However, having looked through some pictures, I decided to depict a family of T.rexes vanquishing a rival.

Furthermore, I’ve revamped how my profiles will go. Putting down various sections in the profiles that I think are up to snuff. I likely will rewrite a lot of the animals’ profiles in the coming days with this new system.

Now, I could have gone into a ton more detail about things like, Tyrannosaurus’ growth stages, its appearance in the Jurassic Park Franchise, the various specimens, etc. However, that is stuff for future profiles, fact sheets, etc. that I have planned down the line.

Interesting fact, even in the 2000s, the Carnegie Museum’s (Holotype) still had the outdated Kangaroo pose.
Source: I had a friend from my Pre-K class who went there, and they had a pic of it from 2003 on the wall. As well as:
Carnegie's Famed Dinosaurs Get a Makeover : NPR
It wasn’t unveiled till ~2007.

Speaking of makeover, I had to revamp a lot of these guys in order to get them up to snuff to my standards.

Huge thanks to randomdinos Paleonerd01 and Franoys for their skeletal diagrams. I had to widen the torso for the adults, gave the skull some modifications for the base model, and I had to remake some of the skulls. What do I mean?
The adults in the pic are more different than at first glance: The one in the foreground is based on my state’s most iconic T.rex Sue. The one that’s dead is actually based on AMNH 5027 (Rexy). Finally, the one in the background is based on MOR 008 (Custer’s Rex).

Here’s a pic comparing them:
i.imgur.com/Dhmcw0l.jpg

Will this be in PMP? Obviously. This is the star of Episode 6, and I’ve got some great scenes planned out for this icon. So glad to finally put this profile out and hope you guys have a great new year! Episode 3 will be done in a few more days. I accidentally saved over one of the paddocks which I had to rebuild (just finished) and I also have to get the promo shots ready for Episode 4.

In the meantime, hope you guys have a great New Year, and I’m looking forward to seeing where my art and stories go this year.
Original Mesh and Skin by Tyranachu, mesh modified by me:
Tyrannosaurus (Tyranachu) | ZT2 Download Library Wiki | Fandom