In The Tyrannosaurus Chronicles: The Biology and Evolution of the World's Most Famous Predator, renowned tyrannosaurus expert David Hone provides the most complete understanding of the evolution and all aspects of the lives of these amazing ancient reptiles and their contemporaries in the light of the latest paleontological research.
Too often, when it comes to tyrannosaurs - or any dinosaurs for that matter - the main focus of attention falls on one tyrannosaurus. Among all the dinosaurs, he is much more famous general public, and as a result, almost every discovery of a new dinosaur (and even many non-dinosaurs) seems to be compared to it. Such is the appeal and recognition of the dinosaur “tyrant king” that he has become a media standard, regardless of whether he is related to any particular story.
Of course, the tyrannosaurus was a surprisingly interesting animal in its own way, but excessive attention to it as a kind of benchmark for comparison is often unjustified. It was no more a typical dinosaur than aardvarks, lemurs or kangaroos are typical mammals. He was an animal with features honed by pressure evolutionary selection down to a form very different from most other theropods and, even to the extreme, from most other tyrannosaurs. Although Tyrannosaurus's closest relatives in the genera Tarbosaurus and Zhuchentyrannus were very similar to it, it stands out among them in that it has been disproportionately studied over the decades, and because as a consequence we now know more about it than about any other dinosaur, Tyrannosaurus rex became the best model for future research. Like the fruit fly Drosophila (Drosophila melanogaster)- the centerpiece of genetic research, the smooth clawed frog (Xenopus laevis)- neurology, and a small round worm is a nematode (Caenorhabditis elegans)- developmental biology, so Tyrannosaurus is the key animal for most dinosaur research. This has clearly contributed to its overvaluation in the public eye (and even in some scientific circles), but it also means that it is the most studied of all dinosaurs.
We simply know more about Tyrannosaurus Rex than any other extinct dinosaur, and as a result its biology is an excellent subject for discussion (and, for me, as luck would have it, an ideal topic for writing a book).
The downside to this situation is that I have had to refer to Tyrannosaurus a lot more often than I would have liked, simply because it is often the only member of the clade for which that particular trait or behavior has been confirmed. Other taxa are poorly understood, and although some are actually quite new (such as Yutyrannus and Lithronax) and others are known from very little material (Proceratosaurus, Aviatyrannis) or both (Nanucsaurus), further work is required much more research into the anatomy, evolution, and especially the ecology and behavior of many non-tyrannosaurine tyrannosaurs. It is likely that early forms, partly due to their relative unspecialization, can in some sense be grouped with animals like the small Megalosaurus or Allosaurus in terms of potential prey, feeding methods, etc. However, Tyrannosaurus is especially interesting not so much for what kind of animal it was , as well as how it became that way, as well as the evolutionary paths that turned early tyrannosaurs into such incredible animals as Albertosaurines and Tyrannosaurines.
Another problem is that dinosaurs in general, and T. rex in particular, can give some people some very strange ideas. No field of science is exempt from occasional eccentric concepts, which can come from even talented and respected scientists, not just “fringe” authors. Even if some controversial issues are eventually resolved in academic circles, information about it does not necessarily go beyond these circles; “scientists have reached an agreement” is not as exciting news as “new scandalous discussions around the tyrannosaurus rex.” Thus, the public often only gets to hear the beginning of the story, with much less attention paid to what follows. This, first of all, became the reason that the topic of “predator or scavenger” is endlessly discussed, while, firstly, it was hardly worth raising at all, and secondly, it has been dismantled to pieces in the scientific literature more than once times (most extensively by paleontologist Tom Holtz in 2008).
Some of these points have already been mentioned by me, while others have been largely omitted for the sake of clarity in the presentation of the relevant chapters, but they are worth returning to because they usually give rise to misconceptions or have a significant influence on our understanding of these animals. I will add here that in recent years there has been a situation where the media are taking seriously ideas that can only be called intriguing out of generosity: for example, that dinosaurs lived in water or that they evolved on other planets in parallel worlds and are alive and well to this day, having escaped mass extinction in their cosmic home. I won't delve into such fringe ideas here (they're covered in more detail on the internet), but there is serious debate in the scientific literature about some plausible theories, and they're hard to ignore. And the first - and main - of them is the problem of nanotyrannus.
Baby Tyrannosaurus?
The collections of the Cleveland Museum of Natural History display a very modest-sized theropod skull. This skull is clearly that of a tyrannosaurine: the broad rear quickly tapers towards the front, converging to a long but still broad snout with a rounded end, and the jaws contain a relatively small number of large teeth.
In fact, it looks quite similar to the skull of a Tyrannosaurus rex, only less than half the expected size: it is just over 50 cm long. Although this skull appears to have belonged to an animal of considerable size, the creature's total length was probably closer to five meters than the size of a typical adult tyrannosaurus.
Originally described as a Gorgosaurus specimen by paleontologist Charles Gilmore in 1946, this skull was later long years remained the subject of much debate. Partly because it is somewhat younger than Gorgosaurus and may in fact have been contemporary with Tyrannosaurus, but also because it is not a Gorgosaurus skull, but some other animal.
The key question is: did it belong to a juvenile Tyrannosaurus rex, or is it the skull of a miniature Tyrannosaurus rex that lived alongside the most famous of dinosaurs? The second hypothesis was formally proposed by Bob Bakker and his co-authors in a 1988 paper, where they noted that some of the skull bones appeared fused. If so, this represents the skull of an adult specimen, and although the animal may have grown a little later, it was clearly significantly smaller than any other North American tyrannosaurus from the Late Cretaceous, and also deserved recognition as a species. Due to its small size it was called nanotyrannus.
Since then, debate has raged as to whether this animal is a representative of a separate taxon, since the fusion of some skull bones alone can hardly be considered a determining indicator of the maturity of an individual. What is important is this: if the skull represents a new taxon, then Tyrannosaurus is not the only tyrannosaurine of its time in America, and there is a large size gap between Tyrannosaurus and the various dromaeosaurs and troodontids in at least is partially filled with nanotyrannus, and this implies a completely different ecology for predators of this period than previously assumed. At the same time, if the skull belongs to a juvenile Tyrannosaurus, we will have an excellent opportunity to study the growth and development of animals of this species; With a very young specimen of Tarbosaurus already known, there is a huge scope for studying how these animals changed with age and questions about the possible ecological separation between juvenile and adult individuals.
Those who support the designation of Nanotyrannus as a new species point to some features in the morphology of the skull that are not observed in known Tyrannosaurus rex specimens. For example, the jaws of Nanotyrannus have several more teeth, but individual variation is always possible in this area, and it is unclear how the teeth could change as the animal grew. We already know that the proportions of the limbs and the shape of the skull changed, so that some other elements could well appear and disappear during the growth process. However, the number of teeth in gorgosaurs of different ages, appears to have been different, and the same may be true for Tyrannosaurus (even if not applicable to Tarbosaurus), but the number of teeth in Tyrannosaurus in general was probably a highly variable trait. Moreover, additional analyzes, such as those performed by Thomas Carr, suggest that Nanotyrannus and Tyrannosaurus had common features, and the first specimen is a juvenile, not an adult.
This problem is further complicated by the presence of Jane (a name, like most others, given in honor of the merits of an individual, rather than indicative of the individual's sex) - a largely preserved specimen of a young Tyrannosaurine, which has also been attributed to either Nanotyrannus or Tyrannosaurus (see illustration) below). Jane was clearly a juvenile, as her skeleton contains many unfused bony sutures, and some histological evidence also points to a juvenile animal, but is it a juvenile Tyrannosaurus or a second Nanotyrannus? Jane's specimen was over six meters in length at the time of death, and therefore, given the significant growth ahead, it is unlikely to have been a "dwarf" animal; Moreover, it was found to have more teeth than a typical adult Tyrannosaurus, supporting the idea that the number of teeth decreased as it grew. Several features unique to a Tyrannosaurus rex are observed in Jane, also supporting the idea that she is a juvenile Tyrannosaurus rex. However, given the similarity between Jane's skull and the Cleveland find, it can be assumed that the second one is also “just” a young tyrannosaurus.
The skeleton of an individual named Jane, which most researchers consider to be a juvenile Tyrannosaurus rex (an adult skeleton is shown for comparison), but is also hypothesized to be a small species of Tyrannosaurus rex. Note differences in leg length and shape of skull and pelvis
Hawn D. The Tyrannosaurus Chronicles. - M.: Alpina non-fiction, 2017
And the latest complication to the picture is a controversial specimen, recently excavated in the United States and in private hands. A small Tyrannosaurus rex was discovered alongside a ceratopsian, presumably representing the result of a death match (needless to say, most experts are very skeptical about this), and it was hypothesized that this new specimen "solved" the problem of Nanotyrannus. However, although this specimen is for sale, it has not been made available to scientists, so for now this theory remains purely in the realm of fantasy. Somewhat not very good photos a partially assembled specimen is not something on which to base judgment, so for the time being this specimen remains an unfortunate side branch of the overall problem.
There is growing evidence that both Jane and the Cleveland skull belong to true tyrannosaurs, based in part on comparisons with very juvenile Tarbosaurus specimens from Mongolia and growth trends observed in other dinosaurs. If this assumption is correct, we have an excellent growth scale for Tyrannosaurus, further supported by a small fragment of a snout preserved in Los Angeles, belonging to a very small individual, about a year old judging by its size. Essentially, all this suggests that there are certain differences between tyrannosaurines. Even when split, the skull of the small Tarbosaurus looks more like an adult, i.e. it is assumed that the animal retained approximately the same shape of the skull at all ages; it simply became larger.
Meanwhile, Jane's skull is more similar to that of an early Tyrannosaurus or Alioramin (long and narrow, without a wide back); as it grew, the back wall “swelled”, forming the classic shape of a Tyrannosaurus rex skull. This indicates significant changes in the functioning of the skull and, possibly as a result, in the ecology of the animal. IN this moment Despite some valid counterarguments, it is better to consider nanotyrannus an invalid taxon rather than a special dwarf tyrannosaurus, no matter how attractive this idea may seem.
Two Tyrannosaurs?
The nanotyrannus problem is just one of a number of taxonomic complications surrounding the question of whether Tyrannosaurus rex was the only late Cretaceous tyrannosaurus in the Americas, as some experts have suggested that there was a second species of tyrannosaurus. The idea for this so-called Tyrannosaurus X first came from paleontologist Dale Russell, although it was given the nickname X by Bob Bakker. It was based primarily on the fact that some specimens of Tyrannosaurus rex had a pair of small teeth on the front of the dentary rather than just one, and also on the fact that the skulls of some specimens appeared significantly larger than others. Based on these and other proposed differences, further researchers took up the idea and suggested that a second Tyrannosaurus rex might be lurking among the existing rex specimens.
In a sense, this would make sense: it is remarkable that Tyrannosaurus appears to have been the only large predator in its ecosystem, whereas both modern mammalian and ancient dinosaur ecosystems typically had two or more species of large predators present. those. The Tyrannosaurus rex ecosystem looks a little strange. However, data is scarce, and the differences between the animals in question are very small. There are, of course, differences between the specimens we have, but we can expect that at least some of this is due to intraspecific variation, and even a few small consistent differences do not necessarily indicate separate species.
This problem resonates with the idea that known Tyrannosaurus rex specimens have two identifiable types of constitution, designated "powerful" and "gracile" forms: that is, one is considered more dense, the other proportionately more fragile. Moreover, it is assumed that these two types of constitution are not simply related to general differences appearance, like stocky or thin people, they are supposedly linked to implicit sexual dimorphism, where one form is associated with males and the other with females. As mentioned, some dinosaurs (especially Tyrannosaurus rexes) end up with nicknames, but these nicknames are mostly random and not related to the animal's gender, so Sue is no more female than Bucky or Stan are males. Previous ideas of distinguishing males and females based on the number or shape of bony chevrons have proven ineffective, and the only reliable way to identify a sexually mature female is by the presence of medullary bone. However, even here its absence may indicate either that the animal was a male, or that the death occurred outside the breeding season, and not all specimens were studied (for some unknown reason, many museum curators get nervous when you propose sawing up their dinosaur skeletons. - Author's note).
So, do these “morphs” even exist, and if so, do they correspond to males and females? And which one is which? Most researchers remain highly skeptical of these ideas. Data is limited and most of materials do not overlap in terms of the present parts of the skeletons, in addition, there is a scatter in time and space. All specimens, separated by thousands of square kilometers and millions of years, are assigned to the same species, but theoretically they should have been representatives of very different populations. Thus, even if there is a sign indicating the possibility of dividing specimens into two groups, how much this picture will be distorted by the errors of such data and the fact that animals almost certainly changed in size and shape during evolution (the growth and variability of individual individuals will also be cause difficulties)?
This is not to rule out any of the hypotheses discussed, but given the inevitable limitations of such analysis, we should look for much more pronounced and consistent differences between the two putative groups.
We do see subtle differences between all possible closely related species, but even so there are usually some consistent and distinct anatomical features that can be used to differentiate them, and this is the basis of the morphological species concept as applied to dinosaurs. We will inevitably have to wait for additional data: new information should lead to an unambiguous interpretation of the results, and when sufficient quantity fossil specimens, it may be possible to analyze a single population to eliminate many of the problems discussed above.
Research continues, and although controversies still arise and become the subject of debate, in reality they quite often lead to additional research and refinement of ideas, as well as the creation of better and better ones. diagnostic methods and data sets that support or refute current viewpoints. Therefore, controversial ideas can be useful in stimulating new research; problems begin when such assumptions continue to be clinging to long after they have been disproved. The concepts discussed here are at least plausible, advocated and debated by serious scientists, but ideas that are borderline crazy still have value. In any case, they show an inexhaustible fascination with the tyrannosaurus and attention directed towards it.
Tyrannosaurus (lat. Tyrannosaurus - “tyrant lizard) is a monotypic genus of predatory dinosaurs.
A group of coelurosaurs of the theropod suborder with the only valid species Tyrannosaurus rex (Latin rex - “king”).Habitat: about 67-65.5 million years ago in the last century of the Cretaceous period - Maastrichtian.
Habitat: western part of North America, which was then the island of Laramidia.
The last of the lizard-hipped dinosaurs that lived before the cataclysm that ended the era of dinosaurs.
Appearance
A bipedal predator with a massive skull balanced by a long, stiff and heavy tail. The front paws were very small, but very strong, and had two toes with large claws.
The largest species of its family, one of the largest representatives of theropods and the largest land predators in the entire history of the Earth.
Dimensions
The largest known complete skeleton, FMNH PR2081 "Sue", reaches a length of 12.3 meters and a hip height of 4 meters. The weight of this individual during life could reach 9.5 tons.
But fragments were found that belonged to even larger tyrannosaurs. Gregory S. Paul estimates the length of specimen UCMP 118742 (an 81 cm long maxilla) to be approximately 13.6 meters, the hip height to be 4.4 meters, and the mass to be 12 tons.
Lifestyle
Tyrannosaurus was the largest carnivore in its ecosystem and was most likely an apex predator - hunting hadrosaurs, ceratopsians and possibly sauropods. However, some researchers suggest that it fed mainly on carrion. Most scientists believe that Tyrannosaurus could both hunt and feed on carrion (it was an opportunistic predator).
Body type
The neck of Tyrannosaurus, like other theropods, had S-shape, was short and muscular, holding up a massive head. The forelimbs had only two fingers with claws and a small metacarpal bone - a vestige of the third finger. The hind limbs were the longest relative to the body of any theropod.
The spine is composed of 10 cervical, 12 thoracic, five sacral and about 40 caudal vertebrae. The tail was heavy and long, serving as a balancer to balance the massive head and heavy body. Many of the bones of the skeleton were hollow, which greatly reduced their weight while maintaining almost the same strength.
Scull
The largest complete Tyrannosaurus rex skull found reaches a length of about one and a half meters. The skull of Tyrannosaurus rex was different from the skulls of large non-tyrannosaurid theropods. Its back was wide and its snout was narrow, thanks to which the lizard had highly developed binocular vision, allowing the brain to form a reliable model of space, estimating distances and sizes. Presumably, this indicates a predatory lifestyle.
The nasal and some other bones of the skull were combined, preventing foreign objects from getting between them. The skull bones were air-filled and had paranasal sinuses, like other non-avian dinosaurs, which made them lighter and more flexible. These properties indicate a tendency in tyrannosaurids to increase their bite force, which significantly exceeded the bite force of all non-tyrannosaurid theropods in these lizards.
End upper jaw was U-shaped, while most non-tyrannosaurids were V-shaped. This shape made it possible to increase the volume of tissue that the tyrannosaurus tore out of the victim’s body in one bite, and also increased the pressure of the lizard’s front teeth.
Tyrannosaurus rex has well-pronounced heterodontism, the difference in teeth in form and function.
The teeth on the front side of the upper jaw have a D-shaped cross-section, fit tightly together, are equipped with a chisel-shaped blade, reinforcing ridges and are curved inward. Thanks to this, the risk of breaking a tooth during biting and dragging the victim was reduced.
Other teeth are stronger and more massive, more banana-shaped than dagger-shaped, wider apart, and have reinforcing ridges.
The largest tooth found reached a height of 30 centimeters along with the root, being the largest carnivorous dinosaur teeth ever found.
Tyrannosaurids did not have lips; their teeth remained open, like modern crocodiles. On the snout there were large scales with pressure receptors.
Bite force
Research by paleontologists Carl Bates and Peter Falkingham in 2012 suggested that the bite force of the Tyrannosaurus rex was the greatest of any land animal that has ever lived on Earth. Based on the tooth marks on the bones of Triceratops, the rear teeth of an adult Tyrannosaurus could have compressed with a force of 35 to 37 kilonewtons, which is 15 times the greatest measured bite force of an African lion, three and a half times the bite force of an Australian saltwater crocodile, and seven times that of an Australian saltwater crocodile. Allosaurus bite force.
Lifespan
The smallest specimen found, LACM 28471 ("Jordan theropod") had a body mass of 30 kilograms, while the largest, FMNH PR2081 "Sue", weighed more than 5,400 kilograms. Histology of the T. rex bones showed that "Jordan theropod" was two years old at the time of death, and "Sue" was 28 years old. Thus, the maximum lifespan of tyrannosaurs probably reached 30 years.
Paleontologists believe that tyrannosaurs “lived fast and died young” because they reproduced quickly and lived too dangerous a life.
Posture
The initial reconstructions of scientists, who depicted the tyrannosaurus, like other bipedal lizards, in the “three-legged tripod” pose, turned out to be incorrect. Lizards of this type of posture moved, holding their torso, tail and head almost in one line, horizontal with respect to the ground. The tail was straightened and constantly curved to the sides in opposition to the movements of the head.
Forelegs
The forelimbs of the tyrannosaurus are extremely small in relation to the size of the body, reaching only one meter in length. However, their bones have large areas for muscle attachment, indicating great strength.
Scientists believe that they could serve to get up from a resting position, to hold the sexual partner during mating, and also to hold the victim trying to escape.
The exceptionally thick, non-porous surface layer of the bones of these limbs indicates the ability to withstand significant loads. Biceps the shoulder of an adult tyrannosaurus was capable of lifting a load of 200 kilograms. Brachialis muscle worked in parallel with the biceps, increasing elbow flexion. The T. rex's biceps were three and a half times stronger than a human's. The massiveness of the foreleg bones, muscular strength and limited range of motion suggest a special system of the tyrannosaurus's forelimbs, developed to firmly hold prey making desperate efforts to escape.
Leather and feathers
Scientists believe that T. rex had feathers on at least some parts of its body. This version is based on the presence of feathers in related smaller species.
Feathers in tyrannosauroids were first discovered in the small dinosaur Dilong paradoxus from the famous Yixian Formation of China. Its fossilized skeleton, like those of many other theropods from the same formation, was bordered by a layer of filamentous structures usually considered proto-feathers. Larger tyrannosauroids had fossilized scales, so scientists concluded that the number of feathers decreased with age, because. immature individuals were feathered to preserve warmth, and by adulthood the animals large sizes only scales remained. However, subsequent discoveries showed that even some of the larger tyrannosauroids had feathers on most of their bodies.
It is possible that the number of feathers and the nature of the cover could change in tyrannosauroids depending on the time of year, changes in the size of lizards, climate changes or other factors.
Thermoregulation
Most likely, the tyrannosaurus was warm-blooded, as it led a very active lifestyle. This is supported by the high growth rate of tyrannosaurs, similar to that of mammals and birds. Growth charts show that their growth stopped during immaturity, unlike most other vertebrates.
Scientists analyzed the ratio of oxygen isotopes in the bones of tyrannosaurs and found that the temperature of the spine and tibia differed by no more than 4-5 °C, which indicates the ability of the tyrannosaurus to maintain a constant internal body temperature thanks to a metabolism average between the metabolisms of cold-blooded reptiles and warm-blooded ones mammals.
Even if the tyrannosaurus supported constant temperature body, this does not mean that he was completely warm-blooded, since such thermoregulation could be explained by a developed form of mesothermy observed in existing leatherback sea turtles.
Movement
Most of the Tyrannosaurus's mass was removed from its center of gravity; it could reduce this distance by arching its back and tail and pressing its head and limbs towards its body. Most likely, the tyrannosaurus turned rather slowly; it could make a 45° turn in 1-2 seconds.
Tyrannosaurus's maximum speed:
Average estimates are around 39.6 km/h or 11 m/s.
The lowest estimate is from 18 km/h or 5 m/s.
72 km/h or 20 m/s.
Many tracks of large theropods walking have been found, but none have been found left behind by running. This may mean that tyrannosaurs were not capable of running. However, other experts noted the greater development of the muscles of the Tyrannosaurus's legs compared to any modern animal, which gives them reason to believe that it could reach speeds of 40-70 kilometers per hour.
For such a massive animal, falling while running quickly could result in fatal injuries. However, modern giraffes can reach speeds of up to 50 km/h, risking breaking a leg or falling to death not only in the wild, but also in a zoo. It is likely that, in case of need, the tyrannosaurus also exposed itself to this risk.
In a 2007 study, a computer model for measuring running speed estimated T. rex's maximum speed at 29 km/h (8 m/s). By comparison, a sprinter can reach a top speed of 43 km/h (12 m/s). Maximum speed The model estimated a three-kilogram (possibly juvenile) Compsognathus specimen at 64 km/h (17.8 m/s).
Brain and sense organs
Coelurosaurids had enhanced sensory abilities. This is evidenced by the fast and well-coordinated movements of the pupils and head, the ability to detect low-frequency sounds, thanks to which the tyrannosaurus detected prey at long distances, as well as an excellent sense of smell.
It is also believed that the Tyrannosaurus rex had very acute vision. Its binocular range was 55 degrees - more than that of a modern hawk. The visual acuity of a tyrannosaurus was 13 times higher than that of a human, respectively, exceeding the visual acuity of an eagle, which is only 3.6 times higher than that of a human. All this allowed the tyrannosaurus to distinguish objects at a distance of 6 kilometers, while a person can recognize them only at a distance of 1.6 kilometers.
Tyrannosaurus' increased depth perception may have been related to its prey. These included the armored dinosaur Ankylosaurus, the horned dinosaur Triceratops, and the duck-billed dinosaurs, which either ran away or camouflaged and hid.
Tyrannosaurus Rex had large olfactory bulbs and olfactory nerves relative to the size of its entire brain, allowing it to smell carrion over great distances. Tyrannosaurus's sense of smell is likely comparable to that of modern vultures.
The very long cochlea of Tyrannosaurus rex is unusual for theropods. The length of the cochlea is associated with hearing acuity, which shows how important hearing was in his behavior. Studies have shown that Tyrannosaurus rex was best at picking up low-frequency sounds.
The eye sockets of the tyrannosaurus were located so that the gaze was directed forward; the lizard had good binocular vision - better than that of hawks. Horner noted that the pedigree of tyrannosaurs showed a steady improvement binocular vision, while scavengers do not need increased depth perception.
IN modern world excellent stereoscopic vision is characteristic of fast-running predators.
Traces from the teeth of tyrannosaurs on the bones of Triceratops without signs of healing are quite common. Fossils exist that show smaller tyrannosaurids, possibly juvenile Tyrannosaurids, successfully hunting down larger Triceratops.
While studying the "Sue" specimen, Peter Larson found the fibula and caudal vertebrae fused after a fracture, as well as cracks in the facial bones and stuck in cervical vertebrae tooth of another tyrannosaurus. This may indicate aggressive behavior between tyrannosaurs. It is not known for certain whether tyrannosaurs were active cannibals or simply engaged in intraspecific struggle for territory or mating rights.
Further studies showed that the injuries to the facial bones, fibula and vertebrae were caused by an infectious disease.
The current view is that tyrannosaurs occupied different ecological niches depending on size and age, like modern crocodiles and monitor lizards.
Thus, newborn cubs most likely fed on small prey, and as they grew, they switched to larger and larger ones. Perhaps the largest tyrannosaurs hunted for carrion, taking prey from their smaller relatives.
Poisonous saliva
There is a hypothesis that the tyrannosaurus could kill the victim using its infected saliva. Rotten remains of meat could accumulate between the teeth of the Tyrannosaurus rex; the bite of the Tyrannosaurus rex infected the victim with harmful bacteria.
The tyrannosaurus probably tore pieces of meat from the carcass by shaking its head from side to side, as crocodiles do. In one bite, an adult tyrannosaurus could tear out a piece of meat weighing 70 kg from the victim’s body.
Paleoecology
The range of the Tyrannosaurus rex extended from Canada to Texas and New Mexico. In the northern regions of this range, Triceratops dominated among the herbivores, and in the southern regions, sauropods of the Alamosaurus species dominated. Remains of tyrannosaurs have been found in a variety of ecosystems, from inland landmass to wetlands and arid and semi-arid (arid and semi-arid) plains.
Several notable T. rex finds have been made in the Hell Creek Formation. During the Maastrichtian era, the area was subtropical, with a warm and humid climate. The flora is represented mainly by flowering plants, there were coniferous trees like metasequoia and araucaria. Tyrannosaurus shared habitat with Triceratops and the closely related Torosaurus, as well as the duck-billed Edmontosaurus, armored ankylosaur, pachycephalosaurus, thescelosaurus, and the theropods Ornithomimus and Troodon.
Another deposit of Tyrannosaurus rex remains is the Lance Formation of Wyoming. Millions of years ago it was a bayou ecosystem similar to the modern Gulf Coast. The fauna of this formation is very similar to that of Hell Creek, but the ornithomimus niche was occupied by Struthiomimus. A small representative of ceratopsians, Leptoceratops, also lived there.
In the southern regions of its range, the tyrannosaurus lived with the Alamosaurus, Torosaurus, Edmontosaurus, the representative of the ankylosaurs Glyptodontopelta and the giant pterosaur Quetzalcoatlus. It was dominated by semi-arid plains, where the Western Inland Sea formerly lay.
Mouth shut: they had lips. Perhaps tyrannosaurs were not as toothy as they are usually portrayed. New research suggests their sharp, pearly teeth were hidden behind the labial folds. This discovery could change the typical image of a dinosaur showing off its fanged grin.
The deadly fangs of the Cretaceous predator were covered with a rather thin layer of enamel. To avoid destruction of the enamel and, as a result, the tooth, such thin and fragile enamel must be constantly maintained in a moist environment. A study of modern large lizards confirms this theory: all terrestrial species, such as the Komodo dragon, have a closed mouth.
Their lipless cousins, such as crocodiles, live in water, in moist environments, and do not require additional moisture to maintain the surface of their teeth. The tyrannosaurus frightened all inhabitants of the earth (not water!), and he needed lips to protect his 10-15-centimeter teeth and keep them in excellent fighting condition.
Herd mentality: tyrannosaurs moved in packs. This is one of the reasons why you probably won't want to travel back in time to the Cretaceous period. In western Canada, scientists have discovered the remains of three tyrannosaurs moving together. And although the reasons for their death were not established, scientists received new information about the habits of tyrannosaurs.
The three tyrannosaurs discovered were mature specimens that had already seen life. All three knew very well how to survive in their cruel world where dinosaur ate dinosaur. They were about 30 years old - and this is a respectable age for a tyrannosaurus. The skin marks were still visible, and it was even possible to see that one of the dinosaurs had its left paw torn off. They followed each other, but kept their distance. These traces, left 70 million years ago, are the best evidence that dinosaurs formed in herds. 
Adolescence: teenage terror among tyrannosaurs. There is one version that explains why the “Canadian trio” kept their distance from each other. From a very early age, tyrannosaurus cubs engaged in fierce fights with each other. The remains of one of the young dinosaurs, named "Jane" (although the sex of the animal was not determined), suggests that the dinosaur was beaten to a pulp by another young dinosaur.
Jane received a heavy blow to her muzzle and upper jaw, which broke her nose. The enemy was the same age as Jane: his teeth marks matched the size of Jane's teeth. Jane was 12 years old at the time of her death, and these injuries had already healed, leaving her face permanently flattened. This means that the fight happened much earlier, when both dinosaurs were even younger.
By the age of 12, Jane was already a real instrument of death: a baby compared to an adult tyrannosaurus, she reached 7 m in length and 2.5 m in height at the sacrum, and weighed about 680 kg. 
“He or she?”: the gender question. Paleontologists are still struggling to accurately determine the sex of dinosaurs. Even dinosaurs with a crest, a bony collar at the back of the skull, horns, spines and other characteristic features do not have pronounced gender characteristics. It seems that male and female dinosaurs looked the same.
However, take a look at the famous MOR 1125, also known as the B-Rex, one of the Museum of the Rockies' specimens. An information plaque near the exhibit confidently states that the remains belonged to a female individual.
The discovery of MOR 1125 was remarkable in that the dinosaur's femur contained soft fabrics. University of North Carolina paleontologist Mary Schweitzer, while examining them, made a discovery: in the remains she discovered the so-called medullary bone. This is a special structure that is chemically different from other types of bone tissue that appears in females before laying eggs. Thus it was proven that femur belonged to a female who was pregnant at the time of death.
Thanks to this discovery, it became clear that in dinosaurs, as in birds, a sharp increase in estrogen during pregnancy provoked the appearance of medullary bone. 
Tyrannosaurus as a dish for dinner. The brutal interspecies battles between dinosaurs did not end broken noses. If someone's meat was available, and the tyrannosaurus was hungry, it could be considered that "food was served." Even if it meant crunching the bones of a cousin.
To survive in the prehistoric world, dinosaurs needed a lot of meat. A lot of meat. Fossilized dinosaur feces contain remains of semi-digested bones and flesh. This indicates the animal had a fast metabolism, and the dinosaur quickly became hungry again.
There is an opinion in scientific circles that tyrannosaurs were cannibals. Some finds of bones preserved tooth marks, which means that the tyrannosaurus rex bones were gnawed by the tyrannosaurs themselves. Scientists are not sure whether they fed on already dead individuals or killed them on purpose: most likely, both options are correct. 
“By the tooth”: the unique structure of a Tyrannosaurus rex tooth. Dinosaur teeth are a great prop for a horror movie: the dinosaur grabs the victim, sinks its teeth into it, blood sprays, and everyone knows that the victim no longer has a chance. Tyrannosaurs' teeth were as sharp as daggers, but that's not the only reason they were deadly weapons.
While examining the teeth of tyrannosaurs, scientists noticed cracks, and at first mistook them for damage (of course, dinosaurs greedily and frantically devoured food). However, it turned out that this was not damage, but a special structure of the tooth. By capturing the prey, these cracks made it possible to hold the animal firmly, minimizing the possibility of escaping from the dinosaur's mouth. This tooth structure is unique. Perhaps it is her merit that tyrannosaurs went down in history as one of the largest predators on the planet. 
"Little Tyrant": a relative of the Tyrannosaurus rex. In 1988, paleontologist Robert Bakker announced that a new relative had appeared in the tyrannosaurus family, Nanotyrannus (literally, “little tyrant”). The scientist made these conclusions by studying the find, a dinosaur skull from Cleveland University. Compared to the head of tyrannosaurs, this exhibit was much smaller and much narrower. In addition, he had more teeth. But was this predator a miniature relative of the Tyrannosaurus rex or its baby?
Few believed that Tyrannosaurus could change so quickly and so dramatically, and debate over the degree of relationship between Nanotyrannus and Tyrannosaurus lasted for quite some time. And in 2001, the best preserved young tyrannosaurus was discovered in Montana - it turned out to be the same Jane described above. This teenage dinosaur had many similarities to both the Cleveland University find and large tyrannosaurs.
The debate about Jane's species remains open, as does the question of the very existence of the tyrannosaurus subspecies Nanotyrannus. 
They are escorted by intelligence: intelligence allowed tyrannosaurs to become a super-predator. There is another mystery in the evolution of the Tyrannosaurus rex - and it again involves “miniature” dinosaurs.
More recently, in 2016, scientists named and described a new type species of tyrannosaurus, Timurlengia euotica. He got this name in honor of Timurleng, the founder of the Timurid Empire in Central Asia: because the main finds that led to such discoveries were made on the territory of modern Uzbekistan. The second part of the name means " good ears"- this individual had long canals inner ear, designed to capture low-frequency sounds.
But the most interesting thing is the size. Scientists could not understand how a dinosaur measuring 3-4 meters in length, weighing approximately 170-270 kg, i.e. generally about the size of a horse, could survive in ancient world. Moreover: how could it develop into a formidable super-predator weighing more than 7 tons? The answer lies in his intelligence: yes, it was his intelligence that allowed the little predator to dominate the cruel world. 
“Head off your shoulders”: a tyrannosaurus could decapitate an enemy. By studying the bony collar of Triceratops, scientists have discovered new facts about the habits of tyrannosaurs. On the bone collars of Triceratops, teeth marks were found, which indicated that the tyrannosaurus not only grabbed and chewed the Triceratops collar, but also literally pulled it together. The question arises: why would a predator gnaw that part of the animal where there is no meat?
It turns out that an adult Tyrannosaurus rex gnawed off the head of a Triceratops. The neck of the Triceratops was considered a delicacy, and the bony collar served as a hindrance. Proof of this is the traces of teeth on the joints of the neck of the Triceratops, which could only be there if the victim’s head was torn off. 
Tyrannosaurus rex's menacing cooing: they didn't make roaring sounds. To find out what sounds tyrannosaurs made, scientists examined their closest living relatives. By studying the sounds of the so-called archosaurs - crocodiles and birds - paleontologists came to the conclusion that dinosaurs did not make wild roaring sounds that frighten all living things.
If Tyrannosaurus rex made sounds like those made by birds, it would have had an air sac rather than vocal cords. Without vocal cords, the dinosaur would not have been able to roar. The real voice of one of the most dangerous dinosaurs might disappoint you: most likely, it sounded like cooing. 
T. rex (Tyrannosaurus Rex) is by far the most popular dinosaur that has lived on our planet. He became the hero of a huge number of books, films, television shows and even video games.
For a very long time, T-Rex was considered the most powerful carnivore that ever walked the Earth.
10 Little-Known Facts About T-Rex
1. Tyrannosaurus Rex Wasn't the Largest Carnivorous Dinosaur
Most people subconsciously believe that the North American Tyrannosaurus Rex, measuring 12 meters from head to tail and weighing up to 9 tons, was the largest carnivorous dinosaur that ever walked the planet. However, an interesting fact is that in ancient times there were two types of dinosaurs that were larger than T. rex - the South American Giganotosaurus, which weighed about nine tons and grew up to 14 meters long, and the North African Spinosaurus, which weighed more than 10 tons. Unfortunately, these theropods never had the opportunity to fight among themselves, since they lived in different time and in different lands, they were separated by thousands of miles and millions of years.
2. T-Rex's front legs weren't as tiny as many people assume.
One anatomical feature of Tyrannosaurus Rex that many people scoff at is its front legs, which appear disproportionately tiny compared to the rest of its massive body. But in fact, T. rex's front legs were more than 1 meter long and may have been capable of lifting up to 200 kg.
You will be interested to know that the most cartoonish - tiny front legs belong to the giant Carnotaurus. His arms looked like tiny bumps.
3. T-Rex had very bad breath.
Of course, most dinosaurs of the Mesozoic era did not have the ability to brush their teeth, and very few of them had teeth. Some experts believe that the remains of rotten meat, infected with bacteria, which were constantly present between the terrible teeth, made the T. rex bite poisonous. Such a bite would infect (and ultimately kill) the bitten victim. The problem is that this process would likely take days or weeks.
4. Female T-Rexes were larger than males.
We don't know for sure yet, but there is good reason to believe (based on the size of T. rex fossils found and the shape of their hips) that female T. rex outsized their males by 800 kg, which is a sign of sexual dimorphism.
For what? Most probable cause is that females of the species had to lay huge eggs, which is why evolution gave females such large hips, or perhaps females were simply more experienced hunters than males (as is the case with modern lions) and consumed more food.
5. The average lifespan of a T-Rex was about 30 years.
It is difficult to infer the lifespan of dinosaurs from their fossilized remains, but based on analysis of skeletal specimens found, paleontologists suggest that Tyrannosaurus Rex may have lived for up to 30 years. Since this dinosaur was on top the food chain of its range, most likely its death occurred from old age, disease or hunger, and not from fights with predators. It was very rare for a tyrannosaurus to die from the teeth of another predator when it was too young and weak. (By the way, in parallel with T. Rex, Titanosaurs may have lived, whose weight exceeded 50 tons, their life expectancy was about 100 years!)
6. T-Rex hunted and picked up carrion
For years, paleontologists have debated whether T. rex was a brutal killer or a mere scavenger—that is, did it actively hunt or pick up the carcasses of dinosaurs that died of old age or disease? Today these contradictions seem quite strange, since Tyrannosaurus Rex could use these two methods of food simultaneously, like any massive predatory animal that constantly wanted to satisfy its hunger.
7. T. rex subspecies Hatchlings may have been covered in feathers
We all know that dinosaurs are the ancestors of birds, and that some carnivorous dinosaurs (especially raptors) were covered in feathers. Consequently, some paleontologists believe that all tyrannosaurs, including T. rex, must have been covered in feathers at some point in their life cycle, most likely when they first hatched from their eggs. This conclusion is supported by the discovery of feathered Asian tyrannosaurs such as Dilong and the nearly equal T. rex Yutyrannus.
8. Tyrannosaurus Rex, most of all loved to hunt Triceratops
If you think that Mayweather vs. Pacquiao was the most brutal boxing fight, then you are sorely mistaken. Imagine a hungry eight-ton Tyrannosaurus Rex attacking a five-ton Triceratops! Such an unthinkable fight could certainly have happened, since both of these dinosaurs lived in the late Cretaceous period in the lands of North America. Of course, the average T. Rex would prefer to take care of a sick or recently hatched Triceratops. But if he was too hungry, large individuals also became his victims.
Back in 1996, a team of scientists from Stanford University who studied the skull of this dinosaur determined that T. rex bit its prey with a force of 700 to 1400 kg. per square inch, with the same force that the largest modern alligators bite. More detailed studies skulls showed that its bite force was in the range of 2,300 kilograms per square inch. (By comparison, the average adult can bite with about 80 lbs. per inch of force.) Powerful jaws T. Rex may have even been bitten by the horns of Ceratopsus himself!
10. Tyrannosaurus Rex was originally named Manospondylus
When famed paleontologist Edward Pinker Cope unearthed the first fossilized skeleton of T. rex, in 1892, he called the find "Manospondylus gigax - Greek" (giant slender vertebrae). After further impressive fossil exploration, it was then-president of the American Museum of Natural History, Henry Fairfield Osborne, who gave the immortal name Tyrannosaurus Rex, the "tyrannical lizard king."
In the “Reptiles and Amphibians” section, for the first time we decided to talk about such an animal, which previously, undoubtedly, was the king of beasts, if you can call it that. To begin with, we will find out what tyrrhanosaurus means in translation from Latin, let's name the closest relatives of this predator. Then we’ll talk more about his appearance and size. Of course, the article about the Tyrrhanosaurus would not be complete if we did not tell who it hunted, where and when it lived on Earth.
Tyrannosaurus Rex is one of the most famous carnivorous dinosaurs. Can't even compare to him. It owes part of its popularity to the means mass media, especially the release of the film “Jurassic Park”. At the American Museum of Natural History in New York, it is a favorite exhibit among visitors.
The meaning of the name Tyrannosaurus and its closest relatives
Tyrannosaurus - literally translated from Latin as “tyrant lizard”. This name comes from the ancient Greek words - “tyrant” and - “lizard, lizard”. Rex means "king". This is what the famous American biologist and paleontologist Henry Fairfield Osborne, who at that time was the president of the American Museum of Natural History in New York, named and first described this dinosaur in 1905.
The Tyrannosaurus genus belongs to the Tyrannosauridae family and consists of only one species of animals - Tyrannosaurus Rex, a large carnivorous dinosaur. In addition to it, Tyrrhanosaurus includes another subfamily, which includes Albertosaurus, Alectrosaurus, Alioramus, Chingkankousaurus, Daspletosaurus, Eotyrannus, Gorgosaurus, Nanotyrannus and Tarbosaurus.
Dimensions, appearance and structural features of Tirex
The largest and most complete T-Rex skeleton ever found was named Sue, after its discoverer, paleontologist Sue Hendrickson. After carefully measuring Sue's bones, scientists concluded that T-Rex was one of the largest predatory dinosaurs. It was up to 4 meters (13 feet) high and 12.3 meters (40 feet) long. Sue's recent analysis, published in 2011 in the journal PLoS ONE, suggests that Tyrrhanosaurus weighed as much as 9 tons (8,160 kg to be exact).
T-Rex had powerful thighs and a long, strong tail., which served not only as a deadly weapon, but primarily as a counterweight to its large head (Sue's skull is 1.5 m, or 5 feet in length) and allowed the dinosaur to move quickly. In 2011, studies were conducted that were able to model the distribution of muscle tissue throughout the lizard skeleton. According to the results obtained, it can be assumed that this predatory dinosaur could reach speeds of 17 to 40 km/h (10-25 mph).
The two-toed front paws were so insignificant that it becomes very unlikely that T. rex could have used them for hunting or with their help to bring food to the mouth. "We don't know why it needed those little paws," University of Kansas paleontologist David Burnham said honestly.
Tyrannosaurus has the strongest bites of any animal
A 2011 study of T. Rex's massive skull, published in the journal Biology Letter, found that the dinosaur's bite could be considered the most powerful bite of any animal that has ever lived on Earth. These figures reached an impressive figure of 12,814 lbf (57,000 Newtons).
T-Rex had the strongest and sharp teeth , the largest of which reached 12 inches in length. But according to a 2012 study published in the journal Earth Sciences, not all teeth served the same function. In particular, the dinosaur grabbed food with its front teeth, the side teeth tore it into pieces, and the back teeth ground it and sent pieces of food further along the digestive tract. It should be noted that the front teeth were flat and fit much more tightly together than the side teeth. This eliminated the possibility of breaking a tooth during the capture of the victim, when she was still trying to resist and escape.
Who did Tyrannosaurus hunt?
It is a huge predator that primarily preyed on herbivorous dinosaurs, including Edmontosaurus and Triceratops. "By constantly hunting, this predator consumed hundreds of pounds of meat over the course of its life," Burnham said.
"It's possible that T. Rex shared its catch, but did so reluctantly," Burnham said. “He had a hard life, he was constantly hungry and so he hunted all the time.” Note: dragonflies also have to hunt all the time, you can read about this in.
“Over the years, evidence has been collected that The main occupation of Tyrrhanosaurus was hunting for food. "All of them were indirect and based only on bite marks, on missing teeth found near the remains of other dinosaurs, as well as the presence of tracks and even entire hunting trails of the Tyrannosaurus," Burnham said. But in 2013, in the official journal Proceedings of the National Academy of Sciences, Burnham and his colleagues finally presented direct evidence of the predatory nature of T. rex. They discovered a Tyrannosaurus rex tooth stuck between the tail vertebrae of a duck-billed dinosaur. Moreover, the victim managed to get away from the T-Rex, and over time, this wound with the tooth healed.
"We found the smoking gun!" says Burnham. “Thanks to this discovery, we now know for sure that the monster from our dreams really existed.”
In the journal PLoS ONE in 2010, the results of analyzes of deep bites and cuts obtained from the teeth of a Tyrannosaurus were published. Yet it is unclear whether Tyrannosaurs were prone to cannibalism, fighting to the death with other relatives, or simply eating their remains.
Scientists are confident that Tyrannosaurs hunted both alone and together with other dinosaurs. In 2014, footprints were discovered in the Rocky Mountains of British Columbia that belonged to three dinosaurs from the Tyrannosaurid family. Presumably these were Albertosaurus, Gorgosaurus and Daspletosaurus. A study published in the journal PLoS ONE found that at least relatives of T. rex hunted in packs.
In what places and at what time did T-rex live?
Dinosaur fossils can be found in various rocks dating back to the Maastrichtian stage of the Late Cretaceous period, which was about 65-67 million years ago, at the end of the Mesozoic era. Tyrannosaurus was one of the last dinosaurs to did not evolve into birds, and lived until the Cretaceous-Paleogene extinction, during which the dinosaurs disappeared.
Tyrannosaurus Rex, unlike other land dinosaurs, constantly roamed throughout the western part of North America, which at that time was a huge island - Laramidia. According to National Geographic, more than 50 T-Rex skeletons have been discovered, some of them very well preserved. Even remnants of skin and muscles are visible on them.
Fossil hunter Barnum Brown discovered the first partial skeleton of Tyrannosaurus rex at Hell Creek (Montana) in 1902 and after some time sold it to the Carnegie Museum of Natural History in Pittsburgh. Other Tyrannosaurus remains are at the American Museum of Natural History in New York.
In 2007, scientists discovered a T. rex footprint in Hell Creek and published the discovery in the journal Palaios. But if this print really belongs to a Tyrannosaurus, then it will be the second one that paleontologists have found. The first trace was discovered in 1993 in New Mexico.
Loading...