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64-493: Tyrannosaurinae (or tyrannosaurines ) is one of the two extinct subfamilies of Tyrannosauridae , a family of coelurosaurian theropods that consists of at least three tribes and several genera . All fossils of these genera have been found in the Late Cretaceous deposits of western North America and east Asia . Compared to the related subfamily Albertosaurinae , tyrannosaurines overall are more robust and larger though

128-548: A cladistic analysis of the Tyrannosauridae. He concluded that there were two subfamilies : the more primitive Aublysodontinae , characterized by unserrated premaxillary teeth ; and the Tyrannosaurinae . The Aublysodontinae included Aublysodon , the " Kirtland Aublysodon ", and Alectrosaurus . Holtz also found that Siamotyrannus exhibited some of the synapomorphies of the tyrannosauridae, but lay "outside

192-406: A crack in the tooth ending in a round void called an ampulla. Tyrannosaurid teeth were used as holdfasts for pulling meat off a body, so when a tyrannosaur would have pulled back on a piece of meat, the tension could cause a purely crack-like serration to spread through the tooth. However, the presence of the ampulla would have distributed these forces over a larger surface area , and lessened

256-486: A 1902 expedition of the American Museum of Natural History , led by Barnum Brown . Initially, Osborn considered these to be distinct species. The first, he named Dynamosaurus imperiosus ("emperor power lizard"), and the second, Tyrannosaurus rex ("king tyrant lizard"). A year later, Osborn recognized that these two specimens actually came from the same species. Despite the fact that Dynamosaurus had been found first,

320-429: A 1902 expedition of the American Museum of Natural History , led by Barnum Brown . Initially, Osborn considered these to be distinct species. The first, he named Dynamosaurus imperiosus ("emperor power lizard"), and the second, Tyrannosaurus rex ("king tyrant lizard"). A year later, Osborn recognized that these two specimens actually came from the same species. Despite the fact that Dynamosaurus had been found first,

384-644: A new name for them: Albertosaurus sarcophagus ("flesh-eating Alberta lizard"). Cope described more tyrannosaur material in 1892, in the form of isolated vertebrae, and gave this animal the name Manospondylus gigas . This discovery was mostly overlooked for over a century, and caused controversy in the early 2000s when it was discovered that this material actually belonged to, and had name priority over, Tyrannosaurus rex . In his 1905 paper naming Albertosaurus , Osborn described two additional tyrannosaur specimens that had been collected in Montana and Wyoming during

448-875: A newly described tribe of tyrannosaurids; the Alioramini. Qianzhousaurus further reveals that similar long-snouted tyrannosaurids were widely distributed throughout Asia and would have shared the same environment while avoiding competition with larger and more robust tyrannosaurines by hunting different prey. Gorgosaurus Albertosaurus Qianzhousaurus Alioramus remotus Alioramus altai Nanuqsaurus Teratophoneus Lythronax Daspletosaurus torosus Daspletosaurus horneri Zhuchengtyrannus Tarbosaurus Tyrannosaurus Albertosaurus Gorgosaurus Daspletosaurus Two Medicine taxon Teratophoneus Bistahieversor Lythronax Nanuqsaurus Tarbosaurus Zhuchengtyrannus Sergei Kurzanov In 1998

512-401: A plexiglass bar with incisions called "kerfs" and drilled holes was more than 25% stronger than one with only regularly placed incisions. Unlike tyrannosaurs and other theropods, ancient predators like phytosaurs and Dimetrodon had no adaptations to prevent the crack-like serrations of their teeth from spreading when subjected to the forces of feeding. The skull was perched at the end of

576-564: A prominent sagittal crest , which ran longitudinally along the sagittal suture and separated the two supratemporal fenestrae on the skull roof. Behind these fenestrae, tyrannosaurids had a characteristically tall nuchal crest, which also arose from the parietals but ran along a transverse plane rather than longitudinally. The nuchal crest was especially well-developed in Tyrannosaurus , Tarbosaurus and Alioramus . Albertosaurus , Daspletosaurus and Gorgosaurus had tall crests in front of

640-402: A thick, S -shaped neck, and a long, heavy tail acted as a counterweight to balance out the head and torso, with the center of mass over the hips. Tyrannosaurids are known for their proportionately very small two-fingered forelimbs, although remnants of a vestigial third digit are sometimes found. Tarbosaurus had the shortest forelimbs compared to its body size, while Daspletosaurus had

704-527: A tyrannosaurid were found in the Horseshoe Canyon Formation of Alberta , and consisted of nearly complete skulls with partial skeletons. These remains were first studied by Edward Drinker Cope in 1876, who considered them a species of the eastern tyrannosauroid Dryptosaurus . In 1905, Henry Fairfield Osborn recognized that the Alberta remains differed considerably from Dryptosaurus , and coined

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768-501: A variety of research into their biology . Scientific studies have focused on their ontogeny , biomechanics and ecology , among other subjects. The first remains of tyrannosaurids were uncovered during expeditions led by the Geological Survey of Canada , which located numerous scattered teeth. These distinctive dinosaur teeth were given the name Deinodon ("terrible tooth") by Joseph Leidy in 1856. The first good specimens of

832-543: Is a family in rank-based Linnaean taxonomy , within the superfamily Tyrannosauroidea and the suborder Theropoda . Tyrannosauridae is uncontroversially divided into two subfamilies. Albertosaurinae comprises the North American genera Albertosaurus and Gorgosaurus , while Tyrannosaurinae includes Daspletosaurus , Teratophoneus , Bistahieversor , Tarbosaurus , Nanuqsaurus , Zhuchengtyrannus , and Tyrannosaurus itself. Some authors include

896-595: Is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to fifteen genera , including the eponymous Tyrannosaurus . The exact number of genera is controversial, with some experts recognizing as few as three. All of these animals lived near the end of the Cretaceous Period and their fossils have been found only in North America and Asia . Although descended from smaller ancestors , tyrannosaurids were almost always

960-474: Is considered by some experts to be a juvenile. Albertosaurus , Gorgosaurus and Daspletosaurus all measured between 8 and 9 metres (26 and 30 ft) long, while Tarbosaurus reached lengths of 11 metres (36 ft) from snout to tail. The massive Tyrannosaurus reached 13 metres (43 ft) in the largest specimen, RSM P2523.8 . Tyrannosaurid skull anatomy is well understood, as complete skulls are known for all genera but Alioramus , which

1024-408: Is fossil evidence of earlier tyrannosauroids having feathers, the evidence of such structures in tyrannosaurids is controversial as a study in 2017 from Bell and colleagues found no support in feathered integument in tyrannosaurids. The study used skin impressions which are small, found widely dispersed across the post-cranium at different regions of the body with a pattern similar to crocodiles. Further

1088-628: Is known only from partial skull remains. Tyrannosaurus , Tarbosaurus , and Daspletosaurus had skulls that exceeded 1 m (3.3 ft) in length. Adult tyrannosaurids had tall, massive skulls, with many bones fused and reinforced for strength. At the same time, hollow chambers within many skull bones and large openings ( fenestrae ) between those bones helped to reduce skull weight. Many features of tyrannosaurid skulls were also found in their immediate ancestors, including tall premaxillae and fused nasal bones . Tyrannosaurid skulls had many unique characteristics, including fused parietal bones with

1152-704: Is nested within Tyrannosaurinae, but it is most often recovered as the sister taxon to Tyrannosauridae instead. The cladogram below displays the position of the Tyrannosaurinae within Eutyrannosauria and Tyrannosauridae, based on the results of phylogenetic analyses performed by Voris et al. (2020): Dryptosaurus aquilunguis Appalachiosaurus montgomeriensis Bistahieversor sealeyi Gorgosaurus libratus Albertosaurus sarcophagus Tyrannosaurinae As of 2023, at least three lineages of tyrannosaurines have been suggested. The basalmost clade

1216-668: Is the Alioramini . The second clade to diverge is the Teratophoneini , which comprises the American southwest taxa Dynamoterror , Lythronax , and Teratophoneus . They are sister to a third clade comprising Nanuqsaurus and the clade containing Daspletosaurini , which includes Daspletosaurus and Thanatotheristes , and the Tyrannosaurini , which includes Zhuchengtyrannus , Tarbosaurus , and Tyrannosaurus . The cladogram below displays

1280-442: Is unclear when the arctometatarsus first evolved; it was not present in the earliest tyrannosauroids like Dilong , but was found in the later Appalachiosaurus . This structure also characterized troodontids , ornithomimids and caenagnathids , but its absence in the earliest tyrannosauroids indicates that it was acquired by convergent evolution . A comparative analysis of the teeth suggests that tyrannosaurids, as well as

1344-633: The Kaiparowits Formation of southern Utah. Later, fossils from the same formation were discovered and identified as the genus. Argon-argon radiometric dating indicates that the Kaiparowits Formation was deposited between 76.1 and 74.0 million years ago, during the Campanian stage of the Late Cretaceous period. This date means that Teratophoneus lived in the middle of the Campanian stage of

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1408-562: The Maastrichtian stage. Fossils have been found in different formations in what is now east Asia and western North America. While the Asian alioramins are the basal most group of the tyrannosaurines, the geographic placement of albertosaurines and other eutyrannosaurian tyrannosauroids found in North America suggests greatly the tyrannosaurines are North American in origin. Prior to the 2010s,

1472-509: The Soviet Union began expeditions into Mongolia , and uncovered the first tyrannosaur remains from Asia. Evgeny Maleev described new Mongolian species of Tyrannosaurus and Gorgosaurus in 1955, and one new genus: Tarbosaurus ("terrifying lizard"). Subsequent studies, however, showed that all of Maleev's tyrannosaur species were actually one species of Tarbosaurus at different stages of growth. A second species of Mongolian tyrannosaurid

1536-460: The Deinodontidae is Deinodon , which was named after isolated teeth from Montana . However, in a 1970 review of North American tyrannosaurs, Dale Russell concluded that Deinodon was not a valid taxon, and used the name Tyrannosauridae in place of Deinodontidae, stating that this was in accordance with ICZN rules. Therefore, Tyrannosauridae is preferred by modern experts. Tyrannosaurus

1600-583: The Late Cretaceous. In the same year Zhuchengtyrannus was named by David W. E. Hone and colleagues based on the holotype ZCDM V0031, a nearly complete right maxilla and associated left dentary (lower jaw, both with teeth) housed at Zhucheng Dinosaur Museum. In 2014 came Nanuqsaurus , the northern most tyrannosaurid found in Prince Creek Formation of the North Slope of Alaska , United States. In

1664-462: The [ family ] proper." Later in the same paper, he proposed that Tyrannosauridae be defined as "all descendants of the most recent common ancestor of Tyrannosaurus and Aublysodon ". He also criticized definitions previously proposed by other workers, like one proposed by Paul Sereno , that the Tyrannosauridae was "all taxa closer to "Tyrannosaurus" than to Alectrosaurus , Aublysodon , and Nanotyrannus ". Holtz observed that since Nanotyrannus

1728-438: The absence of a bony prong connecting the nasal and lacrimal bones. Alioramus was found to be the closest relative of Tarbosaurus in this study, based on a similar pattern of stress distribution in the skull. A related study also noted a locking mechanism in the lower jaw shared between the two genera. In a separate paper, Currie noted the possibility that Alioramus might represent a juvenile Tarbosaurus , but stated that

1792-415: The alioramins were gracile by comparison. This subfamily also includes Lythronax , one of the oldest known tyrannosaurid genera, as well as the youngest and most famous member of the group, Tyrannosaurus rex . The first remains of tyrannosaurids were uncovered during expeditions led by the Geological Survey of Canada , which located numerous scattered teeth. These distinctive dinosaur teeth were given

1856-438: The croc analogy Thomas Carr and colleagues in 2017 by studying the snout of Daspletosaurus suggested they have large scales with sensory sensory neuron pits under the skin. This notion has been challenged from other authors who suggested a more lip-covering of the teeth. The temporal range for tyrannosaurines went from almost 80.6 million years ago in the Campanian stage of the Late Cretaceous epoch to 66 million years ago in

1920-440: The definition. Holtz redefined the clade in 2004 to use all of the above as specifiers except for Alioramus and Alectrosaurus , which his analysis could not place with certainty. However, in the same paper, Holtz also provided a completely different definition, including all theropods more closely related to Tyrannosaurus than to Eotyrannus . The most recent definition is that of Sereno in 2005, which defined Tyrannosauridae as

1984-553: The exception, as they were more comparable in built to albertosaurines and have longirostrine snouts. Like albertosaurines, tyrannosaurines also had heterodont dentition, large heads design to catch and kill their prey, and short didactyl arms. Based on the growth stages of Tyrannosaurus (and possibly Tarbosaurus ), tyrannosaurines undergone ontogenetic changes from gracile or slender, semi-longirostrine immatures to robust, heavy-headed adults. This implies that these animals occupy different ecological niches as they developed. While there

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2048-429: The extent seen in other large theropods like abelisaurids or carnosaurs . The third metatarsals of tyrannosaurids were pinched between the second and fourth metatarsals, forming a structure known as the arctometatarsus . Tyrannosaurids also had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. It

2112-442: The eyes on the lacrimal bones , while Tarbosaurus and Tyrannosaurus had extremely thickened postorbital bones forming crescent-shaped crests behind the eyes. Alioramus had a row of six bony crests on top of its snout, arising from the nasal bones; lower crests have been reported on some specimens of Daspletosaurus and Tarbosaurus , as well as the more basal tyrannosauroid Appalachiosaurus . The snout and other parts of

2176-423: The frontals. In 2014, Lü Junchang et al. described the Alioramini as a tribe within the Tyrannosauridae containing the genera Alioramus and Qianzhousaurus . Their phylogenetic analysis indicated that the tribe was located at the base of the Tyrannosaurinae. Some authors, such as George Olshevsky and Tracy Ford, have created other subdivisions or tribes for various combinations of tyrannosaurids within

2240-681: The holotype ( PIN 3141/1) is a partial skull associated with three metatarsals found by a joint Soviet-Mongolian expedition to the Gobi Desert in the early 1970s found these remains at a locality known as Nogon-Tsav in the Mongolian province of Bayankhongor , Nemegt Formation . From 1977 to 2009 saw the publications of several genera. In Asia they include Shanshanosaurus (1977), Maleevosaurus (1992), and Raptorex (2009), while in North America saw Nanotyrannus (1988), Dinotyrannus and Stygivenator (1995). These genera, however are controversial as

2304-726: The largest predators in their respective ecosystems , putting them at the apex of the food chain . The largest species was Tyrannosaurus rex , the most massive known terrestrial predator, which measured over 13 metres (43 ft) in length and according to most modern estimates up to 8.87 metric tons (9.78 short tons) in weight. Tyrannosaurids were bipedal carnivores with massive skulls filled with large teeth. Despite their large size, their legs were long and proportioned for fast movement. In contrast, their arms were very small, bearing only two functional digits . Unlike most other groups of dinosaurs, very complete remains have been discovered for most known tyrannosaurids. This has allowed

2368-415: The least inclusive clade containing Albertosaurus , Gorgosaurus and Tyrannosaurus . Cladistic analyses of tyrannosaurid phylogeny often find Tarbosaurus and Tyrannosaurus to be sister taxa , with Daspletosaurus more basal than either. A close relationship between Tarbosaurus and Tyrannosaurus is supported by numerous skull features, including the pattern of sutures between certain bones,

2432-485: The longest. Tyrannosaurids walked exclusively on their hindlimbs, so their leg bones were massive. In contrast to the forelimbs, the hindlimbs were longer compared to body size than almost any other theropods. Juveniles and even some smaller adults, like more basal tyrannosauroids, had longer tibiae than femora , a characteristic of cursorial (fast-running) dinosaurs like ornithomimids . Larger adults had leg proportions characteristic of slower-moving animals, but not to

2496-487: The much higher tooth count and more prominent nasal crests in Alioramus suggest it is a distinct genus. Similarly, Currie uses the high tooth count of Nanotyrannus to suggest that it may be a distinct genus, rather than a juvenile Tyrannosaurus as most other experts believe. However, the discovery and description of Qianzhousaurus reveals that Alioramus is not a close relation to Tarbosaurus , instead belonging to

2560-570: The name Deinodon ("terrible tooth") by Joseph Leidy in 1856. In 1892 Edward Drinker Cope described more tyrannosaur material in the form of isolated vertebrae, and gave this animal the name Manospondylus gigas . This discovery was mostly overlooked for over a century, and caused controversy in the early 2000s when it was discovered that this material actually belonged to, and had name priority over, Tyrannosaurus rex . Later in 1905 Henry Fairfield Osborn described two tyrannosaur specimens that had been collected in Montana and Wyoming during

2624-613: The name Tyrannosaurus had appeared one page earlier in his original article describing both specimens. Therefore, according to the International Code of Zoological Nomenclature (ICZN), the name Tyrannosaurus was used. Barnum Brown went on to collect several more tyrannosaurid specimens from Alberta, including the first to preserve the shortened, two-fingered forelimbs characteristic of the group (which Lawrence Lambe named Gorgosaurus libratus , "balanced fierce lizard", in 1914). A second significant find attributed to Gorgosaurus

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2688-405: The name Tyrannosaurus had appeared one page earlier in his original article describing both specimens. Therefore, according to the International Code of Zoological Nomenclature (ICZN), the name Tyrannosaurus was used. The second described representative of the tyrannosaurines, Tarbosaurus (originally described as an Asiatic representative of Tyrannosaurus ) was in 1955 after a large skull

2752-546: The oldest known member of Tyrannosauridae, was described in 2013 by Mark A. Loewen and colleagues from a nearly complete specimen that was uncovered in 2009 in the Wahweap Formation of the Grand Staircase–Escalante National Monument . In comparison to the albertosaurines, tyrannosaurines were more heavily built and larger. The alioramin genera of Qianzhousaurus and Alioramus , however, were

2816-402: The other large theropods, had lips that protected their teeth from external damage. This anatomical feature gave these animals more visual resemblance to lepidosaurs than to closely related crocodilians. The name Deinodontidae was coined by Edward Drinker Cope in 1866 for this family, and continued to be used in place of the newer name Tyrannosauridae through the 1960s. The type genus of

2880-411: The presence of a crescent-shaped crest on the postorbital bone behind each eye, and a very deep maxilla with a noticeable downward curve on the lower edge, among others. An alternative hypothesis was presented in a 2003 study by Phil Currie and colleagues, which found weak support for Daspletosaurus as a basal member of a clade also including Tarbosaurus and Alioramus , both from Asia, based on

2944-556: The relationships of the tyrannosaurines was best understood as Tyrannosaurus being a sister taxon to Tarbosaurus . These two genera in turn were the sister taxon to Daspletosaurus , follow by Alioramus . There was an alternative hypothesis from Phil Currie and colleagues (2003) who suggested Daspletosaurus to be more closely related to Tarbosaurus and Alioramus than to Tyrannosaurus based on cranial features. This relationship, however, has not been found in more recent studies. In 1988 Gregory Paul considered all tyrannosaurines at

3008-442: The remains of these animals are immature or juvenile individuals. With the possible exception of Raptorex, it is widely assumed that the Asian specimens are early growth stages of Tarbosaurus , whereas the North American specimens are those of Tyrannosaurus . Valid genera would not be named until the 2010s, where in 2011 announced the publication of Teratophoneus by Thomas D. Carr and colleagues. The fossils were first found in

3072-564: The rest. Unlike earlier tyrannosauroids and most other theropods, the maxillary and mandibular teeth of mature tyrannosaurids are not blade-like but extremely thickened and often circular in cross-section, with some species having reduced serrations. Tooth counts tend to be consistent within species, and larger species tend to have lower tooth counts than smaller ones. For example, Alioramus had 76 to 78 teeth in its jaws, while Tyrannosaurus had between 54 and 60. William Abler observed in 2001 that Albertosaurus tooth serrations resemble

3136-754: The results of the strict consensus phylogenetic analysis performed by Scherer & Voiculescu-Holvad (2023), indicating the distinct lineages of tyrannosaurines. Alioramus remotus Alioramus altai Qianzhousaurus sinensis Dynamoterror dynastes Teratophoneus curriei Lythronax argestes Nanuqsaurus hoglundi Thanatotheristes degrootorum Daspletosaurus horneri Daspletosaurus wilsoni Daspletosaurus torosus TMP 2001.36.1 Zhuchengtyrannus magnus Tarbosaurus bataar Tyrannosaurus rex [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Tyrannosauridae Tyrannosauridae (or tyrannosaurids , meaning " tyrant lizards")

3200-458: The risk of damage to the tooth under strain. The presence of incisions ending in voids has parallels in human engineering. Guitar makers use incisions ending in voids to, as Abler describes, "impart alternating regions of flexibility and rigidity" to the wood they work with. The use of a drill to create an "ampulla" of sorts and prevent the propagation of cracks through material is also used to protect airplane surfaces. Abler demonstrated that

3264-447: The same year also announced Qianzhousaurus known from a partial sub-adult individual consisting of a nearly complete skull with the lower jaws missing all teeth (lost during fossilization), 9 cervical vertebrae , 3 dorsal vertebrae , 18 caudal vertebrae, both scapulocoracoids , partial ilia , and the left hindlimb compromising the femur , tibia , fibula , astragalus with calcaneum , and metatarsals III and IV. Lythronax ,

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3328-405: The skull also sported numerous foramina . According to the 2017 study which described D. horneri , scaly integument as well as tactile sensitivity was correlated with the multiple rows of neurovascular foramina seen in crocodilians and tyrannosaurids. Tyrannosaurids, like their tyrannosauroid ancestors, were heterodonts , with premaxillary teeth D -shaped in cross section and smaller than

3392-453: The skull, the shoulder, a forelimb, the pelvis , a femur and all of the vertebrae from the neck, torso and hip, as well as the first eleven tail vertebrae. It was discovered in 1921 near Steveville, Alberta , by Charles Mortram Sternberg , who thought it was a new species of Gorgosaurus , but was found to be a new genus by Dale Russell using the aforementioned CMN 8506. The second, Alioramus , described in 1976 by Sergei Kurzanov which

3456-468: The species Gorgosaurus libratus in the genus Albertosaurus and Tarbosaurus bataar in the genus Tyrannosaurus , while others prefer to retain Gorgosaurus and Tarbosaurus as separate genera. Albertosaurines are characterized by more slender builds, lower skulls, and proportionately longer tibiae than tyrannosaurines. In tyrannosaurines, the sagittal crest on the parietals continues forward onto

3520-522: The subfamilies. However, these have not been phylogenetically defined, and usually consisted of genera that are now considered synonymous with other genera or species. Additional subfamilies have been named for more fragmentary genera, including Aublysodontinae and Deinodontinae . However, the genera Aublysodon and Deinodon are usually considered nomina dubia , so they and their eponymous subfamilies are usually excluded from taxonomies of tyrannosaurids. An additional tyrannosaurid, Raptorex ,

3584-444: The time except Alioramus to be species of Tyrannosaurus . In the second edition of The Princeton Field Guide to Dinosaurs published in 2016, Paul would continue this thought as well as including Bistahieversor , Teratophoneus , Lythronax , and Nanuqsaurus into the genus as well. This multispecies Tyrannosaurus classification is, however, not widely accepted by most paleontologists. In some phylogenetic studies Bistahieversor

3648-482: Was found later, described by Sergei Kurzanov in 1976, and given the name Alioramus remotus ("remote different branch"), though its status as a true tyrannosaurid and not a more primitive tyrannosaur is still controversial. The tyrannosaurids were all large animals, with all species capable of weighing at least 1 metric ton. A single specimen of Alioramus of an individual estimated at between 5 and 6 metres (16 and 20 ft) long has been discovered, although it

3712-478: Was initially described as a more primitive tyrannosauroid, but likely represents a juvenile tyrannosaurine similar to Tarbosaurus . However, as it is known only from a juvenile specimen, it is also currently considered a nomen dubium . However, Thomas Carr maintains its validity and finds it to be similar to tyrannosaurines. With the advent of phylogenetic taxonomy in vertebrate paleontology, Tyrannosauridae has been given several explicit definitions. The original

3776-415: Was made in 1942, in the form of a well-preserved, though unusually small, complete skull. The specimen waited until after the end of World War II to be studied by Charles W. Gilmore , who named it Gorgosaurus lancesnis . This skull was re-studied by Robert T. Bakker , Phil Currie , and Michael Williams in 1988, and assigned to the new genus Nanotyrannus . It was also in 1946 that paleontologists from

3840-514: Was named by Henry Fairfield Osborn in 1905, along with the family Tyrannosauridae. The name is derived from the Ancient Greek words τυραννος ( tyrannos ) ('tyrant') and σαυρος ( sauros ) ('lizard'). The very common suffix -idae is normally appended to zoological family names and is derived from the Greek suffix -ιδαι - idai , which indicates a plural noun. Tyrannosauridae

3904-406: Was only in 1965 that Ty. bataar and Ta. efremovi were the same species, the latter being a younger animal, and distinct from Tyrannosaurus recognized by A.K. Rozhdestvensky who recombined the species as Tarbosaurus bataar . In the 1970s saw the description of two genera. In 1970 saw the publication of Daspletosaurus , with the holotype CMN 8506 consisting of a partial skeleton including

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3968-447: Was probably a misidentified T. rex juvenile, Sereno's proposed definition would have the family Tyrannosauridae as a subtaxon of the genus Tyrannosaurus . Further, his proposed definition of the subfamily Tyrannosaurinae would also be limited to Tyrannosaurus . A 2003 attempt by Christopher Brochu included Albertosaurus , Alectrosaurus , Alioramus , Daspletosaurus , Gorgosaurus , Tarbosaurus and Tyrannosaurus in

4032-476: Was produced by Paul Sereno in 1998, and included all tyrannosauroids closer to Tyrannosaurus than to either Alectrosaurus , Aublysodon or Nanotyrannus . However, Nanotyrannus is often considered to be a juvenile Tyrannosaurus rex , while Aublysodon is usually regarded as a nomen dubium unsuitable for use in the definition of a clade . Definitions since then have been based on more well-established genera. In 2001, Thomas R. Holtz Jr. published

4096-477: Was recovered in a joint Soviet -Mongolian expedition to the Gobi Desert in the Mongolian Ömnögovi Province in 1946. The holotype was named as Tyrannosaurus bataar by Evgeny Maleev as Tyrannosaurus bataar . The genus Tarbosaurus was also described in the same year based on PIN 551–2, a specimen with a skull and skeletal remains discovered by the same expedition in 1948 and 1949 as Tarbosaurus efremovi . It

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