Daspletosaurus (/dæsˌpliːtəˈsɔːrəs/ das-PLEET-o-SAWR-əs; meaning "frightful lizard") was a genus of tyrannosaurid dinosaur that lived in western North America between about 77 and 74 million years ago, during the Late Cretaceous Period. The genus Daspletosaurus contains two species. Fossils of the earlier type species, D. torosus, have been found in Alberta, while fossils of the later second species, D. horneri, have been found only in Montana. A possible third species, also from Alberta, awaits formal identification. (Daspletosaurus sp.)

Daspletosaurus is closely related to the much larger and more recent tyrannosaurid Tyrannosaurus rex. Like most tyrannosaurids, Daspletosaurus was a multi-tonne bipedal predator equipped with dozens of large, sharp teeth. Daspletosaurus had the small forelimbs typical of tyrannosaurids, although they were proportionately longer than in other genera.

As an apex predator, Daspletosaurus was at the top of the food chain, probably preying on large dinosaurs like the ceratopsid Centrosaurus and the hadrosaur Hypacrosaurus. In some areas, Daspletosaurus coexisted with another tyrannosaurid, Gorgosaurus, though there is some evidence of niche differentiation between the two. While Daspletosaurus fossils are rarer than other tyrannosaurids', the available specimens allow some analysis of the biology of these animals, including social behavior, diet and life history.

Temporal range: Late Cretaceous, 77–74 Ma
Daspletosaurus in Des Moines
Cast skeleton mount of D. torosus on display at the Science Center of Iowa.
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Tyrannosauridae
Subfamily: Tyrannosaurinae
Genus: Daspletosaurus
Russell, 1970
Type species
Daspletosaurus torosus
Russell, 1970
  • Daspletosaurus torosus Russell, 1970
  • Daspletosaurus horneri Carr et al., 2017


D. torosus with a human for scale.

While very large by the standard of modern predators, Daspletosaurus was not the largest tyrannosaurid. Adults could reach a length of 8–9 meters (26–30 ft) from snout to tail.[1] Mass estimates have centered on 2.5 t (2.5 long tons; 2.8 short tons),[1][2][3] but have ranged between 1.8 and 3.8 t (1.8 and 3.7 long tons; 2.0 and 4.2 short tons).[4][5]

Daspletosaurus had a massive skull that could reach more than 1 meter (3 ft 3 in) in length.[1] The bones were heavily constructed and some, including the nasal bones on top of the snout, were fused for strength. Large fenestrae (openings) in the skull reduced its weight. An adult Daspletosaurus was armed with about six dozen teeth that were very long but oval in cross section rather than blade-like. Unlike its other teeth, those in the premaxilla at the end of the upper jaw had a D-shaped cross section, an example of heterodonty always seen in tyrannosaurids. Unique skull features included the rough outer surface of the maxilla (upper jaw bone) and the pronounced crests around the eyes on the lacrimal, postorbital, and jugal bones. The orbit (eye socket) was a tall oval, somewhere in between the circular shape seen in Gorgosaurus and the 'keyhole' shape of Tyrannosaurus.[6][7][8] Split carinae (edges)[9] have been found on Daspletosaurus teeth.[10]

Daspletosaurus torosus steveoc
Restoration of D. torosus

Daspletosaurus shared the same body form as other tyrannosaurids, with a short, S-shaped neck supporting the massive skull. It walked on its two thick hindlimbs, which ended in four-toed feet, although the first digit (the hallux) did not contact the ground. In contrast, the forelimbs were extremely small and bore only two digits, although Daspletosaurus had the longest forelimbs in proportion to body size of any tyrannosaurid. A long, heavy tail served as a counterweight to the head and torso, with the center of gravity over the hips.[1][8]

A study of D. horneri skulls suggest that unlike many depictions of tyrannosaurids, this genus and likely other tyrannosaurids did not possess lips. Comparisons of the skull of this species with modern crocodiles show the same rugose (roughly wrinkled) bone structure that indicates the presence of large flat scales as opposed to lips. As the rough texture descends almost to the tooth line, it is theorized that Daspletosaurus' teeth were not covered by lips, as there would have been no room for such soft tissue.[11][12]

Discovery and naming

Daspletosaurus torosus, Ottawa
The D. torusus holotype specimen mounted at the Canadian Museum of Nature.

The type specimen of Daspletosaurus torosus (CMN 8506) is a partial skeleton including 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. It was not until 1970 that the specimen was fully described by Dale Russell, who made it the type of a new genus, Daspletosaurus, from the Greek δασπλής (dasplēs, stem and connective vowel resulting in dasplēto~) ("frightful") and σαυρος/sauros ("lizard").[13] The type species is Daspletosaurus torosus, the specific name torosus being Latin for 'muscular' or 'brawny'.[1] Aside from the type, there is only one other well-known specimen, RTMP 2001.36.1, a relatively complete skeleton discovered in 2001. Both specimens were recovered from the Oldman Formation in the Judith River Group of Alberta. The Oldman Formation was deposited during the middle Campanian stage of the Late Cretaceous, from about 77 to 76 Ma (million years ago).[14]

Dale Russell also suggested that a specimen of an immature Albertosaurus (CMN 11315) from the younger Horseshoe Canyon Formation in Alberta actually belonged to a third specimen of Daspletosaurus as D. cf. torosus, extending the temporal range of the genus by approximately 3.5 million years into the Maastrichtian. He based this referral on features of its limb and pelvic girdle, as well as the curvature of the hand claws, which he interpreted as traits matching Daspletosaurus. This reassignment was not universally accepted, and thorough re-examination of the specimen favoured its initial referral to Albertosaurus sarcophagus, despite lacking many of the diagnostic skeletal traits used to identify mature tyrannosaurids.[7][15] An additional maxilla and various teeth from an Edmontosaurus-dominated bonebed in the Horseshoe Canyon Formation was also mistakenly referred to Daspletosaurus, but all the tyrannosaurid material has all since been confirmed to belong to Albertosaurus.[16]

Assigned species

Daspletosaurus torosus skull FMNH
Originally believed to be a specimen of Gorgosaurus, this skull was later sold to the Field Museum and is now reassigned to Daspletosaurus

Two or three additional species have been assigned to the genus Daspletosaurus over the years, although as of 2007 none of these species have received a proper description or scientific name. In the meantime, all are designated as Daspletosaurus spp; this does not imply that they all are the same species.[7][8]

Along with the holotype, Russell designated a specimen collected by Barnum Brown in 1913 as the paratype of D. torosus. This specimen (AMNH 5438) consists of parts of the hindleg, the pelvis and some of its associated vertebrae. It was discovered in the Dinosaur Park Formation in Alberta.[7] The Dinosaur Park Formation was formerly known as the Upper Oldman Formation and dates back to the middle Campanian, between 76.5 and 74.8 million years ago.[17] Daspletosaurus fossils are known specifically from the middle to upper section of the formation, between 75.6 and 75.0 million years ago.[18] In 1914, Brown collected a nearly complete skeleton and skull; forty years later his American Museum of Natural History sold this specimen to the Field Museum of Natural History in Chicago. It was mounted for display in Chicago and labeled as Albertosaurus libratus for many years, but after several skull features were later found to be modeled in plaster, including most of the teeth, the specimen (FMNH PR308) was reassigned to Daspletosaurus torosus by Thomas Carr in 1999.[6] A total of eight specimens have been collected from the Dinosaur Park Formation over the years since, most of them within the boundaries of Dinosaur Provincial Park. Phil Currie believes that the Dinosaur Park specimens represent a new species of Daspletosaurus, distinguished by certain features of the skull. Pictures of this new species have been published, but it still awaits a name and full description in print.[7]

Daspletosaurus horneri
D. horneri holotype skull from Montana in Museum of the Rockies

A new tyrannosaurid specimen (OMNH 10131), including skull fragments, ribs and parts of the hindlimb, was reported from New Mexico in 1990 and assigned to the now-defunct genus Aublysodon.[19] Many later authors have reassigned this specimen, along with a few others from New Mexico, to yet another unnamed species of Daspletosaurus.[7][8][20] However, research published in 2010 showed that this species, from the Hunter Wash Member of the Kirtland Formation, is actually a more primitive tyrannosauroid, and was classified in the genus Bistahieversor.[21] There is currently disagreement over the age of the Kirtland Formation, with some workers claiming a late Campanian age,[22] while others suggest a younger age in the early Maastrichtian stage.[23]

In 1992, Jack Horner and colleagues published an extremely preliminary report of a tyrannosaurid from the upper parts of the Campanian Two Medicine Formation in Montana, which was interpreted as a transitional species between Daspletosaurus and the later Tyrannosaurus.[24] Currie (2003) stated that the tyrannosaurid from the Two Medicine Formation mentioned by Horner et al. (1992) may be an unnamed third species of Daspletosaurus.[7] Another partial skeleton was reported from the Upper Two Medicine in 2001, preserving the remains of a juvenile hadrosaur in its abdominal cavity. This specimen was assigned to Daspletosaurus but not to any particular species.[25] The remains of at least three more Daspletosaurus have also been described in a Two Medicine bonebed by Currie et al. (2005); the authors stated that this fossil material likely represents then-unnamed species mentioned by Horner et al. (1992), but cautioned that further study and description of Daspletosaurus would be necessary before the species can be determined with certainty.[26] In 2017, the Two Medicine Formation taxon was named as the new species D. horneri.[12]

Isolated tyrannosaurid teeth in the upper portions of the Judith River Formation are likely from Gorgosaurus as well as some species of Daspletosaurus, probably D. torosus. However, in the lower portion Judith River formation, around 78 million years ago, there is some evidence for a new undescribed tyrannosaurid taxon. A specimen in the collections of Triebold Paleontology excavated between 2002 and 2004, known as "Sir William", shows some characteristics of Daspletosaurus suggesting a new earlier species to the genus. However the specimen shows many characteristics typical of early tyrannosaurines such as Teratophoneus and even some of the later Tyrannosaurus, which may suggest an entirely new genus.[27]

Classification and systematics

Daspletosaurus belongs in the subfamily Tyrannosaurinae within the family Tyrannosauridae, along with Tarbosaurus, Tyrannosaurus and Alioramus. Animals in this subfamily are more closely related to Tyrannosaurus than to Albertosaurus and are known – with the exception of Alioramus – for their robust build with proportionally larger skulls and longer femora than in the other subfamily, the Albertosaurinae.[8][28]

Daspletosaurus is usually considered to be closely related to Tyrannosaurus rex, or even a direct ancestor through anagenesis.[24] Gregory Paul reassigned D. torosus to the genus Tyrannosaurus, creating the new combination Tyrannosaurus torosus,[2] but this has not been generally accepted.[6][8] Many researchers believe Tarbosaurus and Tyrannosaurus to be sister taxa or even to be the same genus, with Daspletosaurus a more basal relative.[8][29] On the other hand, Phil Currie and colleagues find Daspletosaurus to be more closely related to Tarbosaurus and other Asian tyrannosaurids like Alioramus than to the North American Tyrannosaurus.[28] The systematics (evolutionary relationships) of Daspletosaurus may become clearer once all the species have been described.

Daspletosaurus torosus by durbed
FMNH Daspletosaurus
Dinosaur Park specimen (FMNH PR308), mounted at the Field Museum
Daspletosaurus horneri skeleton
Daspletosaurus horneri skeletal mount at the Museum Center at Union Terminal

Below is the cladogram of Tyrannosauridae based on the phylogenetic analysis conducted by Loewen et al. in 2013.[30]


Gorgosaurus libratus Gorgosaurus white background.jpg

Albertosaurus sarcophagus Albertosaurus Clean.png


Dinosaur Park tyrannosaurid (Daspletosaurus sp.) FMNH Daspletosaurus White Background

Daspletosaurus torosus Daspletosaurus-Triebold-800px

Daspletosaurus horneri

Teratophoneus curriei Teratophoneus curriei

Bistahieversor sealeyi

Lythronax argestes

Tyrannosaurus rex Stan T. rex in Oslo white background

Tarbosaurus bataar Yamanashigakuin elementary school Tarbosaurus white background.JPG

Zhuchengtyrannus magnus



There are indications of D. horneri possessing integumentary sensory organs, possibly used in touch, modulation of precise jaw movements, temperature reading, and prey detection. The large flat scales may have further protected the snout during prey capture and intra-specific combat.[31][32][33][12]

Coexistence with Gorgosaurus

Daspletosaurus torDB
Restoration of Daspletosaurus feeding on a ceratopsian

In the late Campanian of North America, Daspletosaurus was a contemporary of the albertosaurine tyrannosaurid Gorgosaurus. This is one of the few examples of two tyrannosaur genera coexisting. In modern predator guilds, similar-sized predators are separated into different ecological niches by anatomical, behavioral or geographical differences that limit competition.[34] Several studies have attempted to explain niche differentiation in Daspletosaurus and Gorgosaurus.

Dale Russell hypothesized that the more lightly built and more common Gorgosaurus may have preyed on the abundant hadrosaurs of the time, while the more robust and less common Daspletosaurus may have specialized on the less prevalent but better-defended ceratopsids, which may have been more difficult to hunt.[1] However, a specimen of Daspletosaurus (OTM 200) from the Two Medicine Formation preserves the digested remains of a juvenile hadrosaur in its gut region.[25] The higher and broader muzzles of tyrannosaurines like Daspletosaurus are mechanically stronger than the lower snouts of albertosaurines like Gorgosaurus, although tooth strengths are similar between the two groups. This may indicate a difference in feeding mechanics or diet.[35]

Other authors have suggested that competition was limited by geographical separation. Unlike some other groups of dinosaurs, there appears to be no correlation with distance from the sea. Neither Daspletosaurus nor Gorgosaurus was more common at higher or lower elevations than the other.[34] However, while there is some overlap, Gorgosaurus appears to be more common at northern latitudes, with species of Daspletosaurus more abundant to the south. The same pattern is seen in other groups of dinosaurs. Chasmosaurine ceratopsians and hadrosaurine hadrosaurs (a group now generally referred to as saurolophines) are also more common in the Two Medicine Formation and in southwestern North America during the Campanian. Thomas Holtz has suggested that this pattern indicates shared ecological preferences between tyrannosaurines, chasmosaurines and hadrosaurines. Holtz notes that, at the end of the later Maastrichtian stage, tyrannosaurines like Tyrannosaurus rex, hadrosaurines and chasmosaurines like Triceratops were widespread throughout western North America, while albertosaurines and centrosaurines became extinct, and lambeosaurines were very rare.[8]

Social behavior

Daspletosaurus torosus models
Two D. torosus models in the Canadian Museum of Nature

A young specimen of the Dinosaur Park Daspletosaurus species (TMP 94.143.1) shows bite marks on the face that were inflicted by another tyrannosaur. The bite marks are healed over, indicating that the animal survived the bite. A full-grown Dinosaur Park Daspletosaurus (TMP 85.62.1) also exhibits tyrannosaur bite marks, showing that attacks to the face were not limited to younger animals. While it is possible that the bites were attributable to other species, intraspecific aggression, including facial biting, is very common among predators. Facial bites are seen in other tyrannosaurs like Gorgosaurus and Tyrannosaurus, as well as in other theropod genera like Sinraptor and Saurornitholestes. Darren Tanke and Phil Currie hypothesize that the bites are due to intraspecific competition for territory or resources, or for dominance within a social group.[36]

Evidence that Daspletosaurus lived in social groups comes from a bonebed found in the Two Medicine Formation of Montana. The bonebed includes the remains of three Daspletosaurus, including a large adult, a small juvenile, and another individual of intermediate size. At least five hadrosaurs are preserved at the same location. Geologic evidence indicates that the remains were not brought together by river currents but that all of the animals were buried simultaneously at the same location. The hadrosaur remains are scattered and bear numerous marks from tyrannosaur teeth, indicating that the Daspletosaurus were feeding on the hadrosaurs at the time of death. The cause of death is unknown. Currie speculates that the daspletosaurs formed a pack, although this cannot be stated with certainty.[26] Other scientists are skeptical of the evidence for social groups in Daspletosaurus and other large theropods;[37]

Daspletosaurus with bite marks
Daspletosaurus skull with bite marks from another tyrannosaur

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.[38] Evidence of cannibalism in Daspletosaurus was published in 2015.[39]

Life history

A graph showing the hypothesized growth curves (body mass versus age) of four tyrannosaurids. Daspletosaurus is shown in green. Based on Erickson et al. 2004.

Paleontologist Gregory Erickson and colleagues have studied the growth and life history of tyrannosaurids. Analysis of bone histology can determine the age of a specimen when it died. Growth rates can be examined when the age of various individuals are plotted against their size on a graph. Erickson has shown that after a long time as juveniles, tyrannosaurs underwent tremendous growth spurts for about four years midway through their lives. After the rapid growth phase ended with sexual maturity, growth slowed down considerably in adult animals. Erickson only examined Daspletosaurus from the Dinosaur Park Formation, but these specimens show the same pattern. Compared to albertosaurines, Daspletosaurus showed a faster growth rate during the rapid growth period due to its higher adult weight. The maximum growth rate in Daspletosaurus was 180 kilograms (400 lb) per year, based on a mass estimate of 1800 kilograms (2 tons) in adults. Other authors have suggested higher adult weights for Daspletosaurus; this would change the magnitude of the growth rate but not the overall pattern.[4]

The growth series of Daspletosaurus horneri sp. nov., based on parsimony analysis
Growth series of D. horneri

By tabulating the number of specimens of each age group, Erickson and his colleagues were able to draw conclusions about life history in a population of Albertosaurus. Their analysis showed that while juveniles were rare in the fossil record, subadults in the rapid growth phase and adults were far more common. While this could be due to preservation or collection biases, Erickson hypothesized that the difference was due to low mortality among juveniles over a certain size, which is also seen in some modern large mammals like elephants. This low mortality may have resulted from a lack of predation, since tyrannosaurs surpassed all contemporaneous predators in size by the age of two. Paleontologists have not found enough Daspletosaurus remains for a similar analysis, but Erickson notes that the same general trend seems to apply.[40]

A 2009 study found evidence of Trichomonas gallinae-like infection in the jaws of various specimens of Daspletosaurus.[41]


D. torosus skeleton cast in the Rocky Mountain Dinosaur Resource Center based on a nearly complete specimen from Montana's Judith River Formation.

All known Daspletosaurus fossils have been found in formations dating to the middle to late Campanian stage of the Late Cretaceous Period, between 77 and 74 million years ago. Since the middle of the Cretaceous, North America had been divided in half by the Western Interior Seaway, with much of Montana and Alberta below the surface. However, the uplift of the Rocky Mountains in the Laramide Orogeny to the west, which began during the time of Daspletosaurus, forced the seaway to retreat eastwards and southwards. Rivers flowed down from the mountains and drained into the seaway, carrying sediment along with them that formed the Two Medicine Formation, the Judith River Group, and other sedimentary formations in the region. About 73 million years ago, the seaway began to advance westwards and northwards again, and the entire region was covered by the Bearpaw Sea, represented throughout the western United States and Canada by the massive Bearpaw Shale.[42][43][44]

Daspletosaurus lived in a vast floodplain along the western shore of the interior seaway. Large rivers watered the land, occasionally flooding and blanketing the region with new sediment. When water was plentiful, the region could support a great deal of plant and animal life, but periodic droughts also struck the region, resulting in mass mortality as preserved in the many bonebed deposits found in Two Medicine and Judith River sediments, including the Daspletosaurus bonebed.[45] Similar conditions exist today in East Africa.[46] Volcanic eruptions from the west periodically blanketed the region with ash, also resulting in large-scale mortality, while simultaneously enriching the soil for future plant growth. It is these ash beds that allow precise radiometric dating as well. Fluctuating sea levels also resulted in a variety of other environments at different times and places within the Judith River Group, including offshore and nearshore marine habitats, coastal wetlands, deltas and lagoons, in addition to the inland floodplains.[43] The Two Medicine Formation was deposited at higher elevations farther inland than the other two formations.[44]

The excellent vertebrate fossil record of Two Medicine and Judith River rocks resulted from a combination of abundant animal life, periodic natural disasters, and the deposition of large amounts of sediment. Many types of freshwater and estuarine fish are represented, including sharks, rays, sturgeons, gars and others. The Judith River Group preserves the remains of many aquatic amphibians and reptiles, including frogs, salamanders, turtles, Champsosaurus and crocodilians. Terrestrial lizards, including whiptails, skinks, monitors and alligator lizards have also been discovered. Azhdarchid pterosaurs, and birds like Apatornis and Avisaurus flew overhead, while several varieties of mammals coexisted with Daspletosaurus and other types of dinosaurs in the various formations that make up the Judith River wedge.[43]

Daspletosaurus juvenle
Skull of a juvenile D. horneri

In the Oldman Formation (the geological equivalent of the Judith River formation), Daspletosaurus torosus could have preyed upon the hadrosaur species Brachylophosaurus canadensis, the ceratopsians Coronosaurus brinkmani and Albertaceratops nesmoi, pachycephalosaurs, ornithomimids, therizinosaurs and possibly ankylosaurs. Other predators included troodontids, oviraptorosaurs, the dromaeosaurid Saurornitholestes and possibly an albertosaurine tyrannosaur (genus currently unknown). The younger Dinosaur Park and Two Medicine Formations had faunas similar to the Oldman, with the Dinosaur Park in particular preserving an unrivaled array of dinosaurs.[43] The albertosaurine Gorgosaurus lived alongside unnamed species of Daspletosaurus in the Dinosaur Park and Upper Two Medicine environments.[34] Young tyrannosaurs may have filled the niches in between adult tyrannosaurs and smaller theropods, which were separated by two orders of magnitude in mass.[1][8][35][47] A Saurornitholestes dentary has been discovered in the Dinosaur Park Formation that bore tooth marks left by the bite of a young tyrannosaur, possibly Daspletosaurus.[48]

See also


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External links


Albertosaurines, or dinosaurs of the subfamily Albertosaurinae, lived in the Late Cretaceous of United States and Canada. The subfamily was first used by Philip J. Currie, Jørn H. Hurum and Karol Sabath as a group of tyrannosaurid dinosaurs. It was originally defined as "(Albertosaurus + Gorgosaurus)", including only the two genera. The group is sister clade to Tyrannosaurinae. In 2007, it was found that the group also contained Maleevosaurus, often synonymized with Tarbosaurus. However, this classification has not been accepted, and Maleevosaurus is still considered a juvenile Tarbosaurus or Tyrannosaurus. Clevenger T. M. McLain found in an abstract, that Alioramus, commonly used as a derived tyrannosauroid, was an albertosaurine, or the sister taxon to the group.


Aublysodon (uncertain derivation; perhaps "backwards-flowing tooth"?) is a genus of carnivorous dinosaurs known only from the Judith River Formation in Montana, which has been dated to the late Campanian age of the late Cretaceous period (about 75 million years ago). The only currently recognized species, Aublysodon mirandus, was named by paleontologist Joseph Leidy in 1868. It is now considered dubious, because the type specimen consists only of an isolated premaxillary (front) tooth. Although this specimen is now lost, similar teeth have been found in many US states, western Canada, and Asia. These teeth almost certainly belong to juvenile tyrannosaurine tyrannosaurids, but most have not been identified to species level. However, it is likely that the type tooth (and therefore the name Aublysodon mirandus itself) belongs to one of the species in the genus Daspletosaurus, which was present in contemporary formations, and which matches specific details of the original tooth. The synapomorphies alleged to distinguish the Aublysodontinae, especially lack of serrations on premaxillary teeth could have been caused by tooth wear in life, postmortem abrasion, or digestion. Most other "aublysodontine"-type teeth may be from ontogenetic stages or sexual morphs of other tyrannosaurids.Apart from the type species Aublysodon mirandus over the years several other species have been named. These are now all considered either dubious or identical to other species or as having no close connection to A. mirandus.

Bone bed

A bone bed is any geological stratum or deposit that contains bones of whatever kind. Inevitably, such deposits are sedimentary in nature. Not a formal term, it tends to be used more to describe especially dense collections such as Lagerstätte. It is also applied to brecciated and stalagmitic deposits on the floor of caves, which frequently contain osseous remains.In a more restricted sense, the term is used to describe certain thin layers of bony fragments, which occur in well-defined geological strata. One of the best-known of these is the Ludlow Bone Bed, which is found at the base of the Downton Sandstone in the Upper Ludlow series. At Ludlow (England) itself, two such beds are actually known, separated by about 14 ft (4.3 m). of strata. Although quite thin, the Ludlow Bone Bed can be followed from that town into Gloucestershire, for a distance of 45 miles (72 km). It is almost completely made up of fragments of spines, teeth and scales of ganoid fish. Another well-known bed, formerly known as the Bristol or Lias Bone Bed, exists in the form of several thin layers of micaceous sandstone, with the remains of fish and saurians, which occur in the Rhaetic Black Paper Shales that lie above the Keuper marls, in the south-west of England. It is noteworthy that a similar bone bed has been traced on the same geological horizon in Brunswick, Hanover (Germany), in Franconia and in Tübingen (Germany). A bone bed has also been observed at the base of the Carboniferous limestone series, in certain parts of the south-west of England.Bone beds are also recorded in North America, South America, Mongolia and China. Terrestrial bonebed examples are: the Triassic Metoposaurus bone bed from Portugal, the Mapusaurus bone bed at Cañadón del Gato, in Argentina, the Allosaurus-dominated Cleveland-Lloyd Dinosaur Quarry of Utah, the Dinosaur National Monument on the boundary of Utah and Colorado, an Albertosaurus bone bed from Alberta, a Daspletosaurus bone bed from Montana, the Cenozoic John Day Fossil Beds of Oregon and the Nemegt Basin in the Gobi Desert region of Mongolia. Bentiaba, Angola, is an example of a marine bonebed with numerous mosasaurs and plesiosaurs.


Corythosaurus is a genus of hadrosaurid "duck-billed" dinosaur from the Upper Cretaceous Period, about 77–75.7 million years ago. It lived in what is now North America. Its name means "helmet lizard", derived from Greek κόρυς. It was named and described in 1914 by Barnum Brown. Corythosaurus is now thought to be a lambeosaurine, related to Nipponosaurus, Velafrons, Hypacrosaurus, and Olorotitan. Corythosaurus has an estimated length of 9 metres (30 ft), and has a skull, including the crest, that is 70.8 centimetres (27.9 in) tall.

Corythosaurus is known from many complete specimens, including the nearly complete holotype found by Brown in 1911. The holotype skeleton is only missing the last section of the tail, and part of the forelimbs, but was preserved with impressions of polygonal scales. Corythosaurus is known from many skulls with tall crests. The crests resemble the crests of the cassowary and a Corinthian helmet. The most likely function of the crest is thought to be vocalization. As in a trombone, sound waves would travel through many chambers in the crest, and then get amplified when Corythosaurus exhaled. A Corythosaurus specimen has been preserved with its last meal in its chest cavity. Inside the cavity were remains of conifer needles, seeds, twigs, and fruits: Corythosaurus probably fed on all of these.

The two species of Corythosaurus are both present in slightly different levels of the Dinosaur Park Formation. Both still co-existed with theropods and other ornithischians, like Daspletosaurus, Brachylophosaurus, Parasaurolophus, Scolosaurus, and Chasmosaurus.

Dale Russell

Dale Alan Russell (born 27 December 1937) is an American-Canadian geologist and palaeontologist. He is currently Research Professor at the Department of Marine Earth and Atmospheric Sciences (MEAS) at North Carolina State University. Dinosaurs he has described include Daspletosaurus, and he was amongst the first paleontologists to consider an extraterrestrial cause (supernova, comet, asteroid) for the extinction of the dinosaurs.In 1982, Russell created the "dinosauroid" thought experiment, which speculated an evolutionary path for Troodon if it had not gone extinct in the Cretaceous–Paleogene extinction event 65 million years ago, and had instead evolved into an intelligent being. Russell commissioned a model of his dinosauroid by artist Ron Sequin, and the concept became popular. Various later anthropologists have continued Russell's speculations about intelligent Troodon-like dinosaurs, though they often find his original idea too anthropomorphic.

Dinosaur Planet (TV series)

Dinosaur Planet is a four-part American nature documentary that aired on the Discovery Channel as a special-two night event on December 14 and 16, 2003. It is hosted by paleontologist Scott Sampson and narrated by actor Christian Slater. It was released on DVD as a two-disc pack on February 17, 2004, and was also released on VHS around the same time.

The format is similar to Discovery's earlier series When Dinosaurs Roamed America. Each episode tells a fictionalized account of a dinosaur from the Late Cretaceous period. The animals are recreated with computer-generated imagery and composited into present-day filmed locations that approximate prehistoric Earth. Periodic interludes (three in each episode) feature Scott Sampson explaining the scientific findings behind the story, also similar to When Dinosaurs Roamed America, but has improved in quality.

Dinosaur Walk Museum

Dinosaur Walk Museum was a series of attractions that feature life-size sculptures of dinosaurs and replicas of fossils. Branches of the museum were located in Riverhead, New York and Pigeon Forge, Tennessee.

The location in Branson, Missouri closed and relocated, and is now known as Branson Dinosaur Museum.


Dynamoterror is a genus of tyrannosaurid theropod dinosaur that lived in what is now New Mexico during the Late Cretaceous Period, approximately 78 million years ago. The type species is Dynamoterror dynastes. The generic name is derived from the Greek word dynamis (δύναμις) meaning "power" and the Latin word terror. The specific name is derived from δυνάστης, "ruler".


Gorgosaurus ( GOR-gə-SOR-əs; meaning "dreadful lizard") is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period (Campanian), between about 76.6 and 75.1 million years ago. Fossil remains have been found in the Canadian province of Alberta and possibly the U.S. state of Montana. Paleontologists recognize only the type species, G. libratus, although other species have been erroneously referred to the genus.

Like most known tyrannosaurids, Gorgosaurus was a bipedal predator weighing more than two metric tons as an adult; dozens of large, sharp teeth lined its jaws, while its two-fingered forelimbs were comparatively small. Gorgosaurus was most closely related to Albertosaurus, and more distantly related to the larger Tyrannosaurus. Gorgosaurus and Albertosaurus are extremely similar, distinguished mainly by subtle differences in the teeth and skull bones. Some experts consider G. libratus to be a species of Albertosaurus; this would make Gorgosaurus a junior synonym of that genus.

Gorgosaurus lived in a lush floodplain environment along the edge of an inland sea. It was an apex predator, preying upon abundant ceratopsids and hadrosaurs. In some areas, Gorgosaurus coexisted with another tyrannosaurid, Daspletosaurus. Although these animals were roughly the same size, there is some evidence of niche differentiation between the two. Gorgosaurus is the best-represented tyrannosaurid in the fossil record, known from dozens of specimens. These plentiful remains have allowed scientists to investigate its ontogeny, life history and other aspects of its biology.

Museum of World Treasures

The Museum of World Treasures is a world history museum in Wichita, Kansas, United States. Among the many items on display are Tyrannosaurus, Daspletosaurus, and Tylosaurus specimens (Including "Ivan the T. rex"), Egyptian mummies, signatures of all the American presidents, a section of the Berlin Wall, and a genuine shrunken head. The Museum of World Treasures is not limited to a particular era of history, but has opted to display an extremely diverse collection representing many different fields of interest and a wide range of subjects. This museum is a member of the American Alliance of Museums, but is not accredited by the organization.

Oldman Formation

The Oldman Formation is a stratigraphic unit of Late Cretaceous (Campanian stage) age that underlies much of southern Alberta, Canada. It consists primarily of sandstones that were deposited in fluvial channel and floodplain environments. It was named for exposures along the Oldman River between its confluence with the St. Mary River and the city of Lethbridge, and it is known primarily for its dinosaur remains and other fossils.

Planet Dinosaur

Planet Dinosaur, is a six-part documentary television series created by Nigel Paterson and Phil Dobree, produced by the BBC, and narrated by John Hurt. It first aired in the United Kingdom in 2011, with VFX studio Jellyfish Pictures as its producer. It is the first major dinosaur-related series for BBC One since Walking with Dinosaurs. There are more than 50 different prehistoric species featured, and they and their environments were created entirely as computer-generated images, for around a third of the production cost that was needed a decade earlier for Walking with Dinosaurs. Much of the series' plot is based on scientific discoveries made since Walking with Dinosaurs. The companion book to Planet Dinosaur was released on 8 September 2011, and the DVD and Blu-ray were released on 24 October 2011.

Prehistoric Beast

Prehistoric Beast is a ten-minute-long experimental animated film conceived, supervised and directed by Phil Tippett in 1984. This sequence is the first film produced by the Tippett Studio, founded by Tippett. Made with the go motion animation technique, scenes from Prehistoric Beast were included in the 1985 full-length documentary Dinosaur!, first aired on CBS in the United States on November 5, 1985.

Steveville, Alberta

Steveville is a ghost town in southeastern Alberta, Canada. In 1910 the community, located near Brooks, had a general store. Named after Steve Hall, a local homesteader, the community never attracted a large population. The Hall family operated a number of businesses in Steveville, including a ferry across the Red Deer River, a boarding house, and the general store and post office.Steveville lies near the northwest boundary of Dinosaur Provincial Park at the edge of the badlands that border the Red Deer River, and it is most notable as the discovery location for many specimens of dinosaurs. These come from the Dinosaur Park Formation of Late Cretaceous (Campanian) age and include remains of Styracosaurus, Daspletosaurus, Corythosaurus, Struthiomimus, and others.


Teratophoneus ("monstrous murderer" (Greek: teras, "monster" and phoneus, "murderer") is a genus of carnivorous tyrannosaurid theropod dinosaur which lived during the late Cretaceous period (late Campanian age, about 77 to 76 million years ago) in what is now Utah, United States. It is known from an incomplete skull and postcranial skeleton recovered from the Kaiparowits Formation. It was specifically named T. curriei in honor of Philip J. Currie.

Timeline of tyrannosaur research

This timeline of tyrannosaur research is a chronological listing of events in the history of paleontology focused on the tyrannosaurs, a group of predatory theropod dinosaurs that began as small, long-armed bird-like creatures with elaborate cranial ornamentation but achieved apex predator status during the Late Cretaceous as their arms shrank and body size expanded. Although formally trained scientists did not begin to study tyrannosaur fossils until the mid-19th century, these remains may have been discovered by Native Americans and interpreted through a mythological lens. The Montana Crow tradition about thunder birds with two claws on their feet may have been inspired by isolated tyrannosaurid forelimbs found locally. Other legends possibly inspired by tyrannosaur remains include Cheyenne stories about a mythical creature called the Ahke, and Delaware stories about smoking the bones of ancient monsters to have wishes granted.Tyrannosaur remains were among the first dinosaur fossils collected in the United States. The first of these was named Deinodon horridus by Joseph Leidy. However, as this species was based only on teeth the name would fall into disuse. Soon after, Edward Drinker Cope described Laelaps aquilunguis from a partial skeleton in New Jersey. Its discovery heralded the realization that carnivorous dinosaurs were bipeds, unlike the lizardlike megalosaurs sculpted for the Crystal Palace. Laelaps was also among the first dinosaurs to be portrayed artistically as a vigorous, active animal, presaging the Dinosaur Renaissance by decades. Later in the century, Cope's hated rival Othniel Charles Marsh would discover that the name Laelaps had already been given to a parasitic mite, and would rename the dinosaur Dryptosaurus.Early in the 20th century, Tyrannosaurus itself was discovered by Barnum Brown and named by Henry Fairfield Osborn, who would recognize it as a representative of a distinct family of dinosaurs he called the Tyrannosauridae. Tyrannosaur taxonomy would be controversial for many decades afterward. One controversy centered around the use of the name Tyrannosauridae for this family, as the name "Deinodontidae" had already been proposed. The name Tyrannosauridae came out victorious following arguments put forth by Dale Russell in 1970. The other major controversy regarding tyrannosaur taxonomy was the family's evolutionary relationships. Early in the history of paleontology, it was assumed that the large carnivorous dinosaurs were all part of one evolutionary lineage ("carnosaurs"), while the small carnivorous dinosaurs were part of a separate lineage (coelurosaurs). Tyrannosaurid anatomy led some early researchers like Matthew, Brown, and Huene, to cast doubt on the validity of this division. However, the traditional carnosaur-coelurosaur division persisted until the early 1990s, when the application of cladistics to tyrannosaur systematics confirmed the doubts of early workers and found tyrannosaurs to be large-bodied coelurosaurs.Another debate about tyrannosaurs would not be settled until the early 21st century: their diet. Early researchers were so overwhelmed by the massive bulk of Tyrannosaurus that some, like Lawrence Lambe, were skeptical that it was even capable of hunting down live prey and assumed that it lived as a scavenger. This view continued to be advocated into the 1990s by Jack Horner but was shown false by Kenneth Carpenter, who reported the discovery of a partially healed tyrannosaur bite wound on an Edmontosaurus annectens tail vertebra, proving that T. rex at least sometimes pursued living victims.


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. 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 the largest predators in their respective ecosystems, putting them at the apex of the food chain. The largest species was Tyrannosaurus rex, one of the largest and most massive known land predators, which measured over 12.3 metres (40 ft) in length and according to most modern estimates 8.4 metric tons (9.3 short tons) to 14 metric tons (15.4 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 a variety of research into their biology. Scientific studies have focused on their ontogeny, biomechanics and ecology, among other subjects.


Zhuchengtyrannus (meaning "Zhucheng tyrant") is a genus of tyrannosaurid theropod dinosaur known from the Late Cretaceous period of Shandong Province, China. It belongs to the tyrannosaurinae subfamily, and contains a single species, Zhuchengtyrannus magnus.



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