Open Paleo

Daspletosaurus

Russell, 1970 das-PLEET-uh-SOR-uhs /dæsˌpliːtəˈsɔːrəs/

From Greek daspletos ('frightful') + sauros ('lizard'), meaning 'frightful lizard'.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Daspletosaurus is a genus of tyrannosaurid dinosaur that lived in Laramidia between about 77 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 in Montana and Alberta. D. wilsoni has been suggested as an intermediate species between D. torosus and D. horneri that evolved through anagenesis, though further research may be required to definitively support the theory.

Diagnosis

  1. Premaxilla does not contact nasal below external naris.
  2. Lacrimal 'horn' triangular in lateral aspect, with apex centered above antorbital ramus of bone; exceeds postorbital 'horn' in development.
  3. Neural spine of fourth cervical vertebra much larger than that of fifth; spine of fifth distally pointed.
  4. In adults humerus length estimated equal to 38 per cent of femur length; forelimb powerfully developed.
  5. Anterodistal condyle of metacarpal I reduced, causing first digit to diverge distally from second.
  6. In adults circumference of femur equals 38 to 41 per cent of femur length.

Species (3)

Daspletosaurus torosus Russell, 1970

Type species

From Latin 'torosus' meaning 'muscular' or 'brawny', a reference to the animal's robust build.

Holotype
NMC 8506 , Canadian Museum of Nature
Material
Skull and skeleton lacking hind limbs.
Horizon
Oldman Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Quarry 88, Alberta, Canada Russell (1970) gives the type as from "quarry 88 of Sternberg 1905", under a pre-1993 Oldman Formation. Powers and colleagues (2026) list CMN 8506 at their quarry Q072, which they call the type locality, 3.867 m below the nearest Oldman-Dinosaur Park Formation contact.

Daspletosaurus horneri Carr et al., 2017

Latinized form of 'Horner', honoring John R. (Jack) Horner for a Two Medicine Formation field program and mentorship.

Holotype
MOR 590 , Museum of the Rockies
Material
Complete skull, partial pectoral limb, and nearly complete hindlimb.
Horizon
upper Two Medicine Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Montana, United States
Diagnosis
  1. Skull taller than in D. torosus, with a shorter rostral ramus of the lacrimal relative to the ventral ramus (rostral ramus longer in D. torosus).
  2. Antorbital fossa of the lacrimal confluent with the ventral ramus of the bone (separated by a deep concavity in D. torosus).
  3. Coronoid region of the surangular facing more laterally than dorsally (facing equally dorsally and laterally in D. torosus).
  4. Primary lacrimal cornual process lower and less prominent, about 53% the height of the rostral ramus (about 69% in D. torosus).
  5. Pneumatic foramen penetrating the lateral surface of the quadratojugal.
  6. Humerus about 34% the length of the femur.

Daspletosaurus wilsoni Warshaw & Fowler, 2022

Latinization of 'Wilson', after John Wilson, discoverer of the holotype.

Holotype
BDM 107 , Badlands Dinosaur Museum
Material
Partial skull and postcranium: premaxillae, maxilla, jugal, lacrimal, quadrate, quadratojugal, dentary, splenial, postorbital, squamosal, cervical/sacral/caudal vertebrae, rib, chevron, metatarsal.
Horizon
Judith River Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Jack's B2, Montana, United States
Diagnosis
  1. Mylohyoid foramen of the splenial elongate and dorsoventrally shallow (much deeper in D. torosus and D. horneri).
  2. Cornual process of the lacrimal short (5.2 cm), intermediate in height between the tall process of D. torosus and the low one of D. horneri.
  3. Prefrontal oriented rostrocaudally (rostromedially to mediolaterally in D. horneri).
  4. Cornual process of the postorbital subdivided into a supraorbital shelf and a caudodorsal tuberosity (undivided in D. horneri).
  5. Dorsal quadrate contact of the quadratojugal broadly visible in lateral view (concealed in D. torosus).
  6. Premaxillary tooth row oriented entirely mediolaterally, concealing all but the distalmost tooth in lateral view (rostromedial, several teeth visible in D. torosus).

Notable specimens

  • “Pete III”

    CMC VP 15826 Museum of Natural History and Science, Cincinnati Museum Center largest individual

    Largest known specimen of Daspletosaurus, suggesting the genus could reach lengths of over 9 meters; its description identified new anatomical features previously unknown from the genus and may represent an unnamed species.

    Warner-Cowgill et al. (2025)

  • OTM 200

    Old Trail Museum gut contents

    Two Medicine Formation specimen preserving the digested remains of a juvenile hadrosaur in its gut region, providing direct evidence that Daspletosaurus fed on hadrosaurs.

    Varricchio (2001)

  • TMP 1985.062.0001

    Royal Tyrrell Museum of Paleontology pathology

    A full-grown Dinosaur Park Daspletosaurus exhibiting tyrannosaur bite marks on its skull, cited as evidence of intraspecific facial biting in the genus.

    Tanke & Currie (1998)

  • FMNH PR308

    Field Museum of Natural History Found 1914 by Barnum Brown historic

    Nearly complete skeleton and skull collected by Barnum Brown, mounted for display in Chicago and labeled Albertosaurus libratus for many years before being reassigned to Daspletosaurus torosus.

    Carr (1999)

References

  1. Russell, D. A. (1970). Tyrannosaurs from the Late Cretaceous of western Canada. Publications in Palaeontology 1. National Museum of Natural Sciences, Ottawa. doi:10.5281/zenodo.1040973 russell1970a
  2. Powers, M. J.; Napoli, J. G.; Coppock, C. C.; Sharpe, H. S.; Garros, C. W.; Demers-Potvin, A. V.; Raun, G. S.; Stock, J. C.; Miyashita, T.; Currie, P. J. (2026). A new albertosaurine from the Oldman Formation, Alberta, Canada, illuminates ambiguity between albertosaurine and tyrannosaurine characteristics. Journal of Vertebrate Paleontology e2728669. Informa UK Limited. doi:10.1080/02724634.2026.2728669

    Lists the holotype CMN 8506 at quarry Q072, 3.867 m below the nearest Oldman-Dinosaur Park Formation contact.

    powers2026a
  3. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the appearance features.

    paul2024a
  4. Warner-Cowgill, E.; Storrs, G. W.; Rogers, R. R.; Maltese, A. E. (2025). Cranial anatomy and stratigraphy of a new specimen of the tyrannosaurine dinosaur Daspletosaurus from the Judith River Formation of Central Montana, USA. Acta Palaeontologica Polonica 70(1): 159-174. doi:10.4202/app.01143.2024 warner-cowgill2025a
  5. Varricchio, D. J. (2001). Gut contents from a Cretaceous tyrannosaurid: implications for theropod dinosaur digestive tracts. Journal of Paleontology 75(2): 401-406. doi:10.1666/0022-3360(2001)075<0401:GCFACT>2.0.CO;2 varricchio2001a
  6. Tanke, D. H.; Currie, P. J. (1998). Head-biting behavior in theropod dinosaurs: paleopathological evidence. Gaia 15(15): 167-184.

    Issue dated 1998 but not printed until 2000.

    tanke1998a
  7. Carr, T. D. (1999). Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria). Journal of Vertebrate Paleontology 19(3): 497-520. doi:10.1080/02724634.1999.10011161 carr1999a
  8. Carr, T. D.; Varricchio, D. J.; Sedlmayr, J. C.; Roberts, E. M.; Moore, J. R. (2017). A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system. Scientific Reports 7: 44942. Springer Science and Business Media LLC. doi:10.1038/srep44942

    Erects Daspletosaurus horneri on skull MOR 590 from the Two Medicine Formation of Montana, proposing anagenesis from D. torosus.

    carr2017a
  9. Warshaw, E. A.; Fowler, D. W. (2022). A transitional species of Daspletosaurus Russell, 1970 from the Judith River Formation of eastern Montana. PeerJ 10: e14461. PeerJ. doi:10.7717/peerj.14461

    Erects Daspletosaurus wilsoni on BDM 107 from the Judith River Formation of Montana, interpreted as morphologically transitional.

    warshaw2022a