Vol.10:1-12.Currie, P.J., Badamgarav, D., Koppelhus, E.B. [1][3][32][33][34][35][36], In 1994, Holtz grouped tyrannosauroids with elmisaurids, ornithomimosaurs and troodonts into a coelurosaurian clade called Arctometatarsalia based on a common ankle structure where the second and fourth metatarsals meet near the tarsal bones, covering the third metatarsal when viewed from the front. [18], Tyrannosaurids, like their tyrannosauroid ancestors, were heterodonts, with premaxillary teeth D-shaped in cross section and smaller than the rest. While earlier tyrannosauroids are found on all three northern continents, tyrannosaurid fossils are known only from North America and Asia. [38] Holtz observed that since Nanotyrannus was probably a misidentified T. rex juvenile, Sereno's proposed definition would have the family Tyrannosauridae as a subtaxon of the genus Tyrannosaurus. 28 Jun 2023 13:04:15 2001. Tyrannosauridae (or tyrannosaurids, meaning " tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous Tyrannosaurus. Despite their large size, their legs were long and proportioned for fast movement. [10][6], The tyrannosaurids were all large animals, with all species capable of weighing at least 1 metric ton. American tyrannosaurids follows Currie (in prep.). Similarly, Currie uses the high tooth count of Nanotyrannus to suggest that it may be a distinct genus,[12] rather than a juvenile Tyrannosaurus as most other experts believe. in 2002. The giant tyrannosaurids were the apex predators of western North America and Asia during the close of the Cretaceous Period. The teeth were estimated to be 81million years old (Campanian Age). A tyrannosaurid growth curve is S-shaped, with the maximum growth rate of individuals around 14 years of age. a.) [20] 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. This slowed after 16 years, and at 18 years of age, the curve plateaus again, indicating that growth slowed dramatically. Such thermoregulation may also be explained by gigantothermy, as in some living sea turtles. The eye-sockets of tyrannosaurs are positioned so that the eyes would point forward, giving them binocular vision slightly better than that of modern hawks. [60] Other scientists are skeptical of the evidence for social groups in Daspletosaurus and other large theropods;[112] Brian Roach and Daniel Brinkman have suggested that Daspletosaurus social interaction would have more closely resembled the modern Komodo dragon, where non-cooperative individuals mob carcasses, frequently attacking and even cannibalizing each other in the process. Chasmosaurine ceratopsians and hadrosaurine hadrosaurs are also more common in the Two Medicine Formation of Montana and in southwestern North America during the Campanian, while centrosaurines and lambeosaurines dominate in northern latitudes. [97], Bony crests are found on the skulls of many theropods, including many tyrannosaurids. ESS 100 Week 9 Quiz Flashcards | Quizlet [133] Fossils from the Fruitland Formation, Kirtland Formation (both Campanian in age), and Maastichtian-aged Ojo Alamo Formation suggest that cannibalism was present in various tyrannosaurid genera of the San Juan Basin. A kerf-and-drill model of tyrannosaur tooth serrations. There is limited evidence of social behavior among the tyrannosaurids. PDF Tyrannosaurid Skeletal Design First Evolved at Small Body Size - AAAS [50][51] The first unquestionable remains of tyrannosaurids occur in the Campanian stage of the Late Cretaceous in North America and Asia. [53] However, a response suggested that critical tyrannosauroid characters were absent from the fossil. [44] They have proposed new subclade names for Tyrannosaurioidea. The Presence of a Furcula in Tyrannosaurid Theropods, and Its - JSTOR The first was by Paul Sereno in 1998, where Tyrannosauroidea was defined as a stem-based taxon including all species sharing a more recent common ancestor with Tyrannosaurus rex than with neornithean birds. [11] A study published in the journal Scientific Reports on February 2, 2016, by Steve Brusatte, Thomas Carr et al. [11] However, as the preservation of behavior in the fossil record is exceedingly rare, these ideas cannot readily be tested. [48] For example, only 600kg (1,300lb) separated the 28-year-old "Sue" from a 22-year-old Canadian specimen (RTMP 81.12.1). [3][38] Other early taxa include Stokesosaurus and Aviatyrannis, known from far less complete material. Alioramus, a possible tyrannosaurid from Mongolia, bears a single row of five prominent bony bumps on the nasal bones; a similar row of much lower bumps is present on the skull of Appalachiosaurus, as well as some specimens of Daspletosaurus, Albertosaurus, and Tarbosaurus. The Chicxulub crater left by the end-Cretaceous asteroid is. Study with Quizlet and memorize flashcards containing terms like A dinosaur is a.) [17], Scientists have commonly understood Tyrannosauroidea to include the tyrannosaurids and their immediate ancestors. Archaean . The most elaborate is found in Guanlong, where the nasal bones support a single, large crest which runs along the midline of the skull from front to back. [59][60], Locomotion abilities are best studied for Tyrannosaurus, and there are two main issues concerning this: how well it could turn; and what its maximum straight-line speed was likely to have been. 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. [109] However, Gorgosaurus appears more common in northern formations like the Dinosaur Park, with species of Daspletosaurus more abundant to the south. Tyrannosaur | Size, Species, & Facts | Britannica [58] However, a 2018 presentation has an alternative interpretation. New Information on Stokesosaurus, a Tyrannosauroid (Dinosauria [20] However, the presence of the ampulla would have distributed these forces over a larger surface area, and lessened the risk of damage to the tooth under strain. But for theropods weighing over 1,000kg (2,200lb), top running speed is limited by body size, so longer legs instead were found to have correlated with low-energy walking. In: Walters, M., Paker, J. The humerus has a subspherical head and reduced deltopectoral Definition 1 / 76 Unossified bone ends Click the card to flip Flashcards Learn Test Match Created by joshhughes9294 Terms in this set (76) Which of the following suggests that Maiasaura had to care for its young? 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. [64] However, Holtz (1998) concluded that tyrannosaurids and their close relatives were the fastest large theropods. [67][68] However, giraffes have been known to gallop at 50km/h (31mph), despite the risk that they might break a leg or worse, which can be fatal even in a "safe" environment such as a zoo. [11] For example, Albertosaurus have been found in aggregations that some have suggested to represent mixed-age packs. Tyrannosauroidea | Paleontology World Dr Makar on Twitter: "Q- Which one of the following conditions [65] Christiansen (1998) estimated that the leg bones of Tyrannosaurus were not significantly stronger than those of elephants, which are relatively limited in their top speed and never actually run (there is no airborne phase), and hence proposed that the dinosaur's maximum speed would have been about 11 metres per second (25mph), which is about the speed of a human sprinter. [47], The Middle Cretaceous record of Tyrannosauroidea is rather patchy. Tyrannosauridsthe familiar group of carnivorous dinosaurs including Tyrannosaurus and Albertosauruswere the apex predators in continental ecosystems in Asia and North America during the latest Cretaceous (ca. [30] Some authors include the species Gorgosaurus libratus in the genus Albertosaurus and Tarbosaurus bataar in the genus Tyrannosaurus,[17][6][31] while others prefer to retain Gorgosaurus and Tarbosaurus as separate genera. Abler, W.L. "The problem here is that we have big tyrannosaurs, some with feathers, some without that live in pretty similar climates. [3][4][5] Tyrannosaurids were bipedal carnivores with massive skulls filled with large teeth. Tyrannosauridae is uncontroversially divided into two subfamilies. A Southern Tyrant Reptile | Science The earliest known tyranosaur remains occurred between 129.4 and 125 million years ago in Ishikawa, Japan near Lat 36.166668 lng 136.633331. tyrannosaur, any of a group of predatory dinosaurs that lived from the late Jurassic Period (about 150 million years ago) to the end of the Cretaceous Period (about 65 million years ago), at which time they reached their greatest dominance. [11], It is unclear when the arctometatarsus first evolved; it was not present in the earliest tyrannosauroids like Dilong,[22] but was found in the later Appalachiosaurus. All of this suggests that Tarbosaurus relied more on its senses of smell and hearing than on its eyesight. [138], By the late Maastrichtian, albertosaurines appear to have gone extinct, while the tyrannosaurine Tyrannosaurus roamed from Saskatchewan to Texas. [2] Eotyrannus also had three functional digits on each hand. [6] This skull was re-studied by Robert T. Bakker, Phil Currie, and Michael Williams in 1988, and assigned to the new genus Nanotyrannus. [10] The hindlimbs of all tyrannosauroids, like most theropods, had four toes, although the first toe (the hallux) did not contact the ground. [122] They have been reported from ceratopsians, hadrosaurs and other tyrannosaurs. At the center of these scales were small keratinised patches. [24], The name Deinodontidae was coined by Edward Drinker Cope in 1866 for this family,[25] and continued to be used in place of the newer name Tyrannosauridae through the 1960s. The Bell et al. The broader feet suggest that adult tyrannosaurids were slower-moving than their offspring. In contrast to the forelimbs, the hindlimbs were longer compared to body size than almost any other theropods. However, in the same paper, Holtz also provided a completely different definition, including all theropods more closely related to Tyrannosaurus than to Eotyrannus. Tyrannosauroid hindlimbs are longer relative to body size than almost any other theropods, and show proportions characteristic of fast-running animals, including elongated tibiae and metatarsals. [125][126], Noted hadrosaur expert Jack Horner is currently the major advocate of the idea that Tyrannosaurus was exclusively a scavenger and did not engage in active hunting at all. The largest species was Tyrannosaurus rex, one of the largest and most massive known land predators, which measured over 13.2 metres (43ft) in length[2] and according to most modern estimates 8.4 metric tons (9.3 short tons) to 14 metric tons (15.4 short tons) in weight. The data "provides compelling evidence of an entirely squamous covering in Tyrannosaurus," the team wrote, although they conceded that plumage may have still been present on the dorsal region where skin impressions haven't been found yet. [51][112][115], While it generally remains controversial, evidence does exist that supports the theory that at least some tyrannosaurids were social. Found by Marsh in 1881 and identified by H.F. Osborne in 1906, the age of the remains was determined by H. Matsuoka et al. Sometimes fragmentary remains uncovered in the Southern Hemisphere have been reported as "Southern Hemisphere tyrannosaurids," although these seem to have been misidentified abelisaurid fossils. [1] Sereno published a new definition in 2005, using Ornithomimus edmontonicus, Velociraptor mongoliensis and Troodon formosus as external specifiers. Ceratopsian | dinosaur group | Britannica [13] This structure was shared by derived ornithomimids, troodontids and caenagnathids,[14] but was not present in basal tyrannosauroids like Dilong paradoxus, indicating convergent evolution. The cause of death is unknown. [1] The arctometatarsus was also present in Appalachiosaurus[8] but it is unclear whether it was found in Eotyrannus[5] or Dryptosaurus. Niche differentiation between the Dinosaur Park tyrannosaurids is not well understood. Tyrannosauridae (or tyrannosaurids, meaning " tyrant lizards") is a family of coelurosaurian theropod dinosaurs which comprises two subfamilies containing up to six genera, including the eponymous Tyrannosaurus. The subordinate regions were analyzed to have cornified epidermis. [12] In 2014, L Junchang et al. 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. [2], Tyrannosaurus was named by Henry Fairfield Osborn in 1905, along with the family Tyrannosauridae. [123] Tooth wear patterns hint that complex head shaking behaviors may have been involved in tyrannosaur feeding. These distinctive dinosaur teeth were given the name Deinodon ("terrible tooth") by Joseph Leidy in 1856. With the advent of phylogenetic taxonomy in vertebrate paleontology, Tyrannosauridae has been given several explicit definitions. [61] The cause of the difficulty is rotational inertia, since much of Tyrannosaurus's mass was some distance from its center of gravity, like a human carrying a heavy timber. The 13-meter long, 7-tonne, bone-crunching Tyrannosaurus rex is a fossil icon 1,2,3.This dinosaur reigned at the top of the food chain in North America at the end of the Cretaceous (~66-67 . During the Campanian and early Maastrichtian, lambeosaurine hadrosaurs and centrosaurine ceratopsians are common in the northwest, while hadrosaurines and chasmosaurines were more common to the south. Evgeny Maleev described new Mongolian species of Tyrannosaurus and Gorgosaurus in 1955, and one new genus: Tarbosaurus ("terrifying lizard"). A newly discovered species of dinosaur, characterized by a wonderfully elaborate head crest, is the oldest known member of the lineage that culminated in Tyrannosaurus rex more than 90 million . [11][17] 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 the absence of a bony prong connecting the nasal and lacrimal bones. Their analysis showed that while juveniles were rare in the fossil record, subadults in the rapid growth phase and adults were far more common. [74], Media related to Tyrannosauroidea at Wikimedia Commons. Tyrannosauridae, a clade of large-bodied theropod dinosaurs restricted to the Late Cretaceous of Laramidia and Asia, represents an ideal group for investigating Laramidian patterns of evolution. The exact number of genera is controversial, with some experts recognizing as few as three. The 13-meter long, 7-tonne, bone-crunching Tyrannosaurus rex is a fossil icon 1,2,3.This dinosaur reigned at the top of the food chain in North America at the end of the Cretaceous (~66-67 million years ago), and was among the last survivors of a major group of carnivorous theropodsthe Tyrannosauroideathat originated more than 100 million years earlier 3,4,5. We really don't know. [17] In Albertosaurus, Gorgosaurus and Daspletosaurus, there is a prominent horn in front of each eye on the lacrimal bone. Early in their existence, tyrannosauroids were small predators with long, three-fingered forelimbs. Which of following statements is false? [15], Tyrannosaurid skull anatomy is well understood, as complete skulls are known for all genera but Alioramus, which is known only from partial skull remains. [99][100] They proposed that tyrannosaurs probably also had bundles of sensory neurons under their facial scales and may have used them to identify objects, measure the temperature of their nests and gently pick-up eggs and hatchlings. Analysis of bone histology can determine the age of a specimen when it died. p. 67", "Dental anatomy and skull length to tooth size ratios support the hypothesis that theropod dinosaurs had lips", "Dinosaur smiles: Do the texture and morphology of the premaxilla, maxilla, and dentary bones of sauropsids provide osteological correlates for inferring extra-oral structures reliably in dinosaurs? ", "Preservation of feather fibers from the Late Cretaceous dinosaur Shuvuuia deserti raises concern about immunohistochemical analyses on fossils", "Ten Things We Don't Know about Tyrannosaurs", https://www.washingtonpost.com/news/speaking-of-science/wp/2017/06/06/tyrannosaurus-rex-had-scaly-skin-and-wasnt-covered-in-feathers-a-new-study-says/, 10.1671/0272-4634(2006)26[321:BVITD]2.0.CO;2, "Complex neuroanatomy in the rostrum of the Isle of Wight theropod Neovenator salerii", "Structure, innervation and response properties of integumentary sensory organs in crocodilians", "Crocodylians evolved scattered multi-sensory micro-organs", "Maximal Aerobic and Anaerobic Power Generation in Large Crocodiles versus Mammals: Implications for Dinosaur Gigantothermy", "Body size overlap, habitat partitioning and living space requirements of terrestrial vertebrate predators: implications for the paleoecology of large theropod dinosaurs", "Gut contents from a Cretaceous tyrannosaurid: implications for theropod dinosaur digestive tracts", 10.1666/0022-3360(2001)075<0401:GCFACT>2.0.CO;2, 10.3374/0079-032X(2007)48[103:AROCPH]2.0.CO;2, "Possible evidence of gregarious behavior in tyrannosaurids", "A 'Terror of Tyrannosaurs': The First Trackways of Tyrannosaurids and Evidence of Gregariousness and Pathology in Tyrannosauridae", "Tyrannosaurus Tracks Show Dinosaur's Walk", "Tracks Hint at the Social Life of Tyrant Dinosaurs", "Geology and taphonomy of a unique tyrannosaurid bonebed from the upper Campanian Kaiparowits Formation of southern Utah: implications for tyrannosaurid gregariousness", "Tyrannosaurs likely hunted in packs rather than heading out solo, scientists find", "Evidence of predatory behavior by theropod dinosaurs", "NEW EVIDENCE FOR CANNIBALISM IN TYRANNOSAURID DINOSAURS FROM THE UPPER CRETACEOUS (CAMPANIAN/MAASTRICHTIAN) SAN JUAN BASIN OF NEW MEXICO", 10.1671/0272-4634(2000)020[0675:TTFTPC]2.0.CO;2, "These 81-million-year-old teeth are the first bit of evidence of Japan's largest ever dinosaur | Irish Examiner", "The Facial Integument of Centrosaurine Ceratopsids: Morphological and Histological Correlates of Novel Skin Structures", https://en.wikipedia.org/w/index.php?title=Tyrannosauridae&oldid=1158480239. . The maximum growth rate in Daspletosaurus was 180 kilograms (400lb) per year, based on a mass estimate of 1,800kg (4,000lb) in adults. [12] In Daspletosaurus, this was a tall oval, somewhere in between the circular shape seen in Gorgosaurus and the 'keyhole' shape of Tyrannosaurus. [43], Paleontologist Gregory Erickson and colleagues have studied the growth and life history of tyrannosaurids. : Southwest Paleontological Symposium Proceedings, 1997, p. 65-78", "A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system", "Tyrannosaurid theropods: did they ever smile like crocodiles? [11][12] Albertosaurus, Gorgosaurus and Daspletosaurus all measured between 8 and 10 metres (26 and 33ft) long,[13] while Tarbosaurus reached lengths of 12 metres (39ft) from snout to tail. [122] Tyrannosaurid bones with tooth marks represent about 2% of known fossils with preserved tooth marks. The phylogeny and evolutionary history of tyrannosauroid dinosaurs - Nature Tooth-marked small theropod bone: An extremely rare trace. [1] Siamotyrannus from the Early Cretaceous of Thailand was originally described as an early tyrannosaurid,[40] but is usually considered a carnosaur today. The exact number of genera is controversial, with some experts recognizing as few as three. We use new tyrannosaurid discoveries from Utahincluding a new taxon which represents the geologically oldest member of the cladeto investigate . A second species of Mongolian tyrannosaurid 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. Researchers reported that a subadult and a juvenile skeleton were found in the same quarry as the "Sue" specimen, which has been used to support the hypothesis that tyrannosaurs may have lived in social groups of some kind. Alioramus, a possible tyrannosaurid from Mongolia, bears a single row of five prominent bony bumps on the nasal bones; a similar row of much lower bumps is present on the skull of Appalachiosaurus, as well as some specimens of Daspletosaurus, Albertosaurus, and Tarbosaurus. [26] The type genus of the Deinodontidae is Deinodon, which was named after isolated teeth from Montana. [39] 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. [8] Derived tyrannosaurids have forelimbs strongly reduced in size, the most extreme example being Tarbosaurus from Mongolia, where the humerus was only one-quarter the length of the femur. [13] Therefore, Tyrannosauridae is preferred by modern experts. and more. 64-83. [3], Neonate sized tyrannosaur fossils have been documented in the scientific literature. Paleontologist Thomas Carr analyzed the craniofacial texture of Daspletosaurus horneri and observed a hummocky rugosity which compared to crocodilian skulls and suggesting Daspletosaurus horneri including all tyrannosaurids have flat sensory scales. For this question below, refer to the phylogenetic tree illustrated below. Tyrannosauridae | TyrannoPedia Wiki | Fandom Analogies can be noted between tyrannosaurids and modern wolves as a result, supported by evidence that at least some tyrannosaurids such as Albertosaurus were hunting in group settings. [104] Later they found similar results in Giganotosaurus specimens, who lived on a different continent and tens of millions of years earlier in time. [129], Evidence also strongly suggests that tyrannosaurids were at least occasionally cannibalistic. [106][107][108], In the Dinosaur Park Formation, Gorgosaurus lived alongside a rarer species of the tyrannosaurine Daspletosaurus. [77]), Studies by Eric Snively et al., published in 2019 indicate that tyrannosaurids such as Tarbosaurus and Tyrannosaurus itself were more manuvrable than allosauroids of comparable size due to low rotational inertia compared to their body mass combined with large leg muscles. Therefore, according to the International Code of Zoological Nomenclature (ICZN), the name Tyrannosaurus was used. [123], Speculation on the pack-hunting habits of Albertosaurus were made by a few researchers who suggest that the younger members of the pack may have been responsible for driving their prey towards the adults, who were larger and more powerful, but also slower. [54] The Australian taxon Timimus, known from a femur, and the Brasilian Santanaraptor, known from a partial juvenile skeleton, have also been suggested to be tyrannosaurs. [64][127][128] Horner has presented several arguments to support the pure scavenger hypothesis. Cladistic analyses of tyrannosaurid phylogeny often find Tarbosaurus and Tyrannosaurus to be sister taxa, with Daspletosaurus more basal than either. Carr, T. D., Varricchio, D. J., Sedlmayr, J. C., Roberts, E. M., & Moore, J. R. (2017). Paleontologists have not found enough Daspletosaurus remains for a similar analysis, but Erickson notes that the same general trend seems to apply. Extinct Taxa", "Phylogenetic taxonomy of the Coelurosauria (Dinosauria; Theropoda)", "Strength indicator values of theropod long bones, with comments on limb proportions and cursorial potential", "Body mass, bone "strength indicator", and cursorial potential of, "The bigger they come, the harder they fall", "The History of Woodland Park Zoo Chapter 4", 10.1671/0272-4634(2002)022[0076:MIAIIA]2.0.CO;2, "Estimating dinosaur maximum running speeds using evolutionary robotics", Liz Seward: "T. rex 'would outrun footballer'", "Lower rotational inertia and larger leg muscles indicate more rapid turns in tyrannosaurids than in other large theropods", "The fast and the frugal: Divergent locomotory strategies drive limb lengthening in theropod dinosaurs", "T. rex was a champion walker, super-efficient at lower speeds", "An exceptionally well-preserved theropod dinosaur from the Yixian Formation of China", "A new Chinese specimen indicates that 'protofeathers' in the Early Cretaceous theropod dinosaur Sinosauropteryx are degraded collagen fibres", "Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution", http://globalnews.ca/news/3506400/tyrannosaurus-rex-fossil-skin-scales-university-of-alberta/, "Tyrannosaurid theropods: did they ever smile like crocodiles? Late Cretaceous dinosaur assemblages of North Americacharacterized by gigantic tyrannosaurid predators, and large-bodied herbivorous ceratopsids and hadrosauridswere highly successful from. The furcula of . [1] These features are found in all known tyrannosauroids, including basal members Guanlong[3] and Dilong. [18][28] In the early 1990s, cladistic analyses instead began to place tyrannosaurids into the Coelurosauria,[14][29] echoing suggestions first published in the 1920s. The superfamily name Tyrannosauroidea was first published in a 1964 paper by the British paleontologist Alick Walker. Unlike some other groups of dinosaurs, neither genus was more common at higher or lower elevations than the other. While predatory theropods in general had binocular vision directly in front of their skull, tyrannosaurs had a significantly larger area of overlap. [11][12][42], Based on comparisons of bone texture of Daspletosaurus with extant crocodilians, a detailed study in 2017 by Thomas D. Carr et al. All fossils of these genera have been found in the Late Cretaceous deposits of western North America and east Asia. By the end of the Cretaceous, centrosaurines are unknown and lambeosaurines are rare, while hadrosaurines and chasmosaurines were common throughout the Western Interior. Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to thirteen genera, including the eponymous Tyrannosaurus. Currie claims this as evidence of pack behavior. Early Cretaceous tyrannosauroid premaxillary teeth are known from the Cedar Mountain Formation in Utah[46] and the Tetori Group of Japan. "Tyrannosaur" redirects here. NMV P186069, a partial pubis (a hip bone) with a supposed distinctive tyrannosauroid-like form, was discovered in Dinosaur Cove in Victoria. [52] The lack of eggshells associated with these specimens has also opened up speculation to the possibility that tyrannosaurids laid soft-shelled eggs as the genera Mussaurus and Protoceratops are believed to have done. They show a tight pattern of fine, non-overlapping pebbly scales (which co-author Scott Persons compared to those seen on the flanks of a crocodile[87]) and preserve no hints of feathering.