page_title: Daspletosaurus
section_title: Assigned species
hierarchical_section_title: Daspletosaurus / Discovery and naming / Assigned species
caption_attribution_description: Daspletosaurus horneri theropod dinosaur skull from the Cretaceous of Montana, USA (public display, MOR 590, Museum of the Rockies, Bozeman, Montana, USA). This complete skull has been identified as a new species of Daspletosaurus by Museum of the Rockies researchers. Others often call this a specimen of Daspletosaurus torosus Russell, 1970. Stratigraphy: Two Medicine Formation, Campanian Stage, Upper Cretaceous. Locality: Glacier County, northwestern Montana, USA Theropod were small to large, bipedal dinosaurs. Almost all known members of the group were carnivorous (predators and/or scavengers). They represent the ancestral group to the birds, and some theropods are known to have had feathers. Some of the most well known dinosaurs to the general public are theropods, such as Tyrannosaurus, Allosaurus, and Spinosaurus.
context_page_description: Daspletosaurus is 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 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.
context_section_description: Two or three additional species have been assigned to the genus Daspletosaurus over the years, although as of 2007 none of these species has 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.
  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. 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. Daspletosaurus fossils are known specifically from the middle to upper section of the formation, between 75.6 and 75.0 million years ago. 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. 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.
  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. Many later authors have reassigned this specimen, along with a few others from New Mexico, to yet another unnamed species of Daspletosaurus. 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. There is currently disagreement over the age of the Kirtland Formation, with some workers claiming a late Campanian age, while others suggest a younger age in the early Maastrichtian stage.
  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. 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. 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. 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. In 2017, the Two Medicine Formation taxon was named as the new species D. horneri.
  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 charact
caption: D. horneri holotype skull from Montana in Museum of the Rockies
exif: {"Image ImageDescription": "", "Image Make": "Canon", "Image Model": "Canon PowerShot D10", "Image Orientation": "Horizontal (normal)", "Image XResolution": "180", "Image YResolution": "180", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS2 Macintosh", "Image DateTime": "2014:09:28 02:38:48", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "272", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1194", "Thumbnail JPEGInterchangeFormatLength": "7435", "EXIF ExposureTime": "1/60", "EXIF FNumber": "16/5", "EXIF ISOSpeedRatings": "250", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2010:08:08 15:47:38", "EXIF DateTimeDigitized": "2010:08:08 15:47:38", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF ShutterSpeedValue": "189/32", "EXIF ApertureValue": "107/32", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "107/32", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash fired, auto mode, red-eye reduction mode", "EXIF FocalLength": "1659/200", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3272", "EXIF ExifImageLength": "2380", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "Interoperability RelatedImageWidth": "4000", "Interoperability RelatedImageLength": "3000", "EXIF InteroperabilityOffset": "1044", "EXIF FocalPlaneXResolution": "4000000/243", "EXIF FocalPlaneYResolution": "1500000/91", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard"}