| Harebell Formation | |
|---|---|
| Stratigraphic range: Maastrichtian, ~ | |
| Type | Geological formation |
| Underlies | Pinyon Conglomerate |
| Location | |
| Extent | Yellowstone National Park (Big Game Ridge) |
The Harebell Formation is a Late Cretaceous (Maastrichtian) [1] geologic formation in Wyoming which outcrops in parts of the Yellowstone National Park. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation. [2]
In 1966, Joseph Leonard Weitz discovered specimen USNM PAL 768805, [3] a right distal premaxillary tooth of a tyrannosaur, from Big Game Ridge, an outcrop of the Harebell Formation within Yellowstone National Park and catalogued it as specimen W-66-1-8A until it was moved to the United States Geological Survey Paleontology collection in Denver, Colorado and was catalogued as specimen D704. [4]
A letter dated 16 November 1966 from J. D. Love to Dr. G. Edward Lewis mentioned that they knew that the tooth was the first dinosaur fossil known from the Yellowstone National Park, [3] and Love (1973) placed USNM PAL 768805 within the Deinodontidae, [4] while Harris et al. (1996) instead listed the tooth as belonging to the Tyrannosauridae. [5]
The specimen was renamed to USMN PAL 768805 in 2021 when it was moved to the Paleobiology Collections of the Smithsonian’s National Museum of Natural History. [3] The tooth was assigned to cf. Tyrannosaurus sp. by Hodnett et al. (2023), who also suggested that it was the shed tooth of a juvenile. [3] [6]
Albertosaurus is a genus of large tyrannosaurid theropod dinosaur that lived in northwestern North America during the early to middle Maastrichtian age of the Late Cretaceous period, about 71 million years ago. The type species, A. sarcophagus, was apparently restricted in range to the modern-day Canadian province of Alberta, after which the genus is named, although an indeterminate species has been discovered in the Corral de Enmedio and Packard Formations of Mexico. Scientists disagree on the content of the genus and some recognize Gorgosaurus libratus as a second species.
Tyrannosaurus is a genus of large theropod dinosaur. The species Tyrannosaurus rex, often called T. rex or colloquially T-Rex, is one of the best represented theropods. It lived throughout what is now western North America, on what was then an island continent known as Laramidia. Tyrannosaurus had a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the Upper Cretaceous period, 68 to 66 million years ago. It was the last known member of the tyrannosaurids and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.
Tyrannosauridae 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.
Tarbosaurus is a genus of tyrannosaurine theropod dinosaur that lived in Asia about 70 million years ago, during the Maastrichtian age at the end of the Late Cretaceous period, considered to contain a single known species: Tarbosaurus bataar. Fossils have been recovered from the Nemegt Formation of Mongolia, with more fragmentary remains found further afield in the Subashi Formation of China.
Daspletosaurus is a genus of tyrannosaurid dinosaur that lived in Laramidia between about 78 and 74.4 million years ago, during the Late Cretaceous Period. The genus Daspletosaurus contains three named species. Fossils of the earlier type species, D. torosus, have been found in Alberta, while fossils of a later species, D. horneri, have been found only in Montana. D. wilsoni has been suggested as an intermediate species between D. torosus and D. horneri that evolved through anagenesis, but this theory has been disputed by other researchers. There are also multiple specimens which may represent new species of Daspletosaurus from Alberta and Montana, but these have not been formally described. The taxon Thanatotheristes has been suggested to represent a species of Daspletosaurus, D. degrootorum, but this has not been widely supported. Daspletosaurus is closely related to the much larger and more recent tyrannosaurid Tyrannosaurus rex. Like most tyrannosaurids, Daspletosaurus was a large bipedal predator, measuring around 8.5–9 metres (28–30 ft) long and weighing up to 2–3 metric tons, equipped with dozens of large, sharp teeth. Daspletosaurus had the small forelimbs typical of tyrannosaurids, although they were proportionately longer than in other genera.
Gorgosaurus 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 the U.S. state of Montana. Paleontologists recognize only the type species, G. libratus, although other species have been erroneously referred to the genus.
Edmontosaurus, often colloquially and historically known as Anatosaurus or Anatotitan, is a genus of hadrosaurid (duck-billed) dinosaur. It contains two known species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian age of the Cretaceous period 73 million years ago, while those of E. annectens were found in the same geographic region from rocks dated to the end of the Maastrichtian age, 66 million years ago. Edmontosaurus was one of the last non-avian dinosaurs to ever exist, and lived alongside dinosaurs like Triceratops, Tyrannosaurus, Ankylosaurus, and Pachycephalosaurus shortly before the Cretaceous–Paleogene extinction event.
Ornithomimus is a genus of ornithomimid theropod dinosaurs from the Campanian and Maastrichtian ages of Late Cretaceous Western North America. Ornithomimus was a swift, bipedal dinosaur which fossil evidence indicates was covered in feathers and equipped with a small toothless beak that may indicate an omnivorous diet. It is usually classified into two species: the type species, Ornithomimus velox, and a referred species, Ornithomimus edmontonicus. O. velox was named in 1890 by Othniel Charles Marsh on the basis of a foot and partial hand from the Denver Formation of Colorado. Another seventeen species have been named since then, though almost all of them have been subsequently assigned to new genera or shown to be not directly related to Ornithomimus velox. The best material of species still considered part of the genus has been found in Alberta, representing the species O. edmontonicus, known from several skeletons from the Horseshoe Canyon Formation. Additional species and specimens from other formations are sometimes classified as Ornithomimus, such as Ornithomimus samueli from the earlier Dinosaur Park Formation.
Aublysodon 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. The only currently recognized species, Aublysodon mirandus, was named by paleontologist Joseph Leidy in 1868. It is sometimes considered dubious now, 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 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.
Alioramus is a genus of tyrannosaurid theropod dinosaurs from the Late Cretaceous period of Asia. It currently contains two species. The type species, A. remotus is known from a partial skull and three foot bones recovered from the Mongolian Nemegt Formation, which was deposited in a humid floodplain about 70 million years ago. These remains were named and described by Soviet paleontologist Sergei Kurzanov in 1976. A second species, A. altai, known from a much more complete skeleton also from the Nemegt Formation, was named and described by Stephen L. Brusatte and colleagues in 2009. Its relationships to other tyrannosaurid genera were at first unclear, with some evidence supporting a hypothesis that Alioramus was closely related to the contemporary species Tarbosaurus bataar. However, the discovery of Qianzhousaurus indicates that it belongs to a distinct branch of tyrannosaurs, namely the tribe Alioramini.
Tyrannosaurinae 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 the alioramins were gracile by comparison. This subfamily also includes the oldest known tyrannosaurid genus Lythronax as well as the youngest and most famous member of the group, Tyrannosaurus rex. There were at least 30 different species of tyrannosaurines.
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 the 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.
The Iren Dabasu Formation is a Late Cretaceous geologic formation in the Iren Nor region of Inner Mongolia. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation. The formation was first described and defined by Henry Fairfield Osborn in 1922 and it is located in the Iren Nor region of China.
The Javelina Formation is a geological formation in Texas. Dating has shown that the strata date to the Maastrichtian stage of the Late Cretaceous, approximately 70 to 66.5 million years old. The middle part of the formation has been dated to about 69 million years ago plus or minus 1 million years and the top situated near the Cretaceous–Paleogene boundary, dated to 66 Ma ago. Dinosaur remains are among the fossils that have been recovered from the formation.
The Pinyon Conglomerate is a geological formation in Wyoming whose strata date back to the Late Cretaceous and Paleocene. Dinosaur remains are among the fossils that have been recovered from the formation.
Lythronax is a genus of tyrannosaurid dinosaur that lived in North America around 81.9-81.5 million years ago during the Late Cretaceous period. The only known specimen was discovered in Utah in the Wahweap Formation of the Grand Staircase–Escalante National Monument in 2009, and it consists of a partial skull and skeleton. In 2013, it became the basis of the new genus and species Lythronax argestes; the generic name Lythronax means "gore king", and the specific name argestes originates from the Greek poet Homer's name for the wind from the southwest, in reference to the specimen's geographic provenance in North America.
Nanuqsaurus is a genus of tyrannosaurine theropod dinosaur known from the Late Cretaceous period Prince Creek Formation of the North Slope of Alaska, having lived roughly 70-68 million years ago. It contains a single species, Nanuqsaurus hoglundi, known only from a partial skull and multiple undescribed postcranial and teeth elements.
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.
Timurlengia is an extinct genus of tyrannosauroid theropod dinosaur found in Uzbekistan, in the Bissekty Formation in the Kyzylkum Desert, hailing from the Turonian age of the early Late Cretaceous. The type species is Timurlengia euotica.
Daspletosaurini is an extinct clade of tyrannosaurine dinosaurs that lived in Laramidia during the Late Cretaceous period. It consists of two genera: Daspletosaurus and Thanatotheristes. Four species have been described in the two genera, namely Daspletosaurus torosus, Daspletosaurus horneri, Daspletosaurus wilsoni, and Thanatotheristes degrootorum. At one point all of them were assigned as specimens of D. torosus, but several papers since 2017 have found them to represent distinct species. Some researchers found anagenesis in the group, whether contained in a daspletosaurin clade or paraphyletic in respect to the lineage of tyrannosaurines leading up to Tyrannosaurus, but a 2023 study refuted this theory on the basis of morphological and stratigraphical data.
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