The Harebell Formation is a

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

(

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

) geologic formation in

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

which outcrops in parts of the

Yellowstone National Park Yellowstone National Park is a List of national parks of the United States, national park of the United States located in the northwest corner of Wyoming, with small portions extending into Montana and Idaho. It was established by the 42nd U ...

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

remains diagnostic to the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

level are among the fossils that have been recovered from the formation.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.

Discovery of the first dinosaur found in Yellowstone

In 1966, Joseph Leonard Weitz discovered specimen USNM PAL 768805, a right distal premaxillary tooth of a

tyrannosaur Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent b ...

, from Big Game Ridge, an outcrop of the Harebell Formation within

and catalogued it as specimen W-66-1-8A until it was moved to the United States Geological Survey Paleontology collection in

Denver Denver ( ) is a List of municipalities in Colorado#Consolidated city and county, consolidated city and county, the List of capitals in the United States, capital and List of municipalities in Colorado, most populous city of the U.S. state of ...

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

and was catalogued as specimen D704. 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, and Love (1973) placed USNM PAL 768805 within the Deinodontidae, while Harris ''et al.'' (1996) instead listed the tooth as belonging to the

Tyrannosauridae Tyrannosauridae (or tyrannosaurids, meaning "tyrant lizards") is a family of coelurosaurian theropod dinosaurs that comprises two subfamilies containing up to fifteen genera, including the eponymous ''Tyrannosaurus''. The exact number of genera ...

. 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 The National Museum of Natural History (NMNH) is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. With 4.4 ...

.Hodnett, John-Paul & Carrano, Matthew & Santucci, Vincent & Tweet, Justin & Visaggi, Christy. (2023). A Tyrannosaur (Dinosauria; Theropoda; Tyrannosauridae) from the Late Cretaceous (Maastrichtian) Harebell Formation of Yellowstone National Park, Wyoming. ''New Mexico Museum of Natural History & Science Bulletin'' 94. 233-238. The tooth was assigned to ''

cf. The abbreviation cf. (short for either Latin or , both meaning 'compare') is generally used in writing to refer the reader to other material to make a comparison with the topic being discussed. However some sources offer differing or even contr ...

'' ''

Tyrannosaurus ''Tyrannosaurus'' () is a genus of large theropod dinosaur. The type species ''Tyrannosaurus rex'' ( meaning 'king' in Latin), often shortened to ''T. rex'' or colloquially t-rex, is one of the best represented theropods. It lived througho ...

'' sp. by Hodnett ''et al.'' (2023), who also suggested that it was the shed tooth of a juvenile.

Paleofauna

* ? ''

Leptoceratops ''Leptoceratops'' (meaning 'small horn face') is a genus of ceratopsian dinosaur from the Late Cretaceous of North America. First found in Alberta in 1910, the type species ''Leptoceratops gracilis'' was named in 1914 by Barnum Brown for a parti ...

'' sp. (neoceratopsia indet) * ''Saurexallopus loevei'' * '' Prodesmodon'' sp. *

Ceratopsidae Ceratopsidae (sometimes spelled Ceratopidae) is a family of ceratopsian dinosaurs including ''Triceratops'', ''Centrosaurus'', and ''Styracosaurus''. All known species were quadrupedal herbivores from the Upper Cretaceous. All but one species are k ...

ident. *

Iguanodontidae Iguanodontidae is a family of iguanodontians belonging to Styracosterna, a derived clade within Ankylopollexia. The clade is formally defined in the ''PhyloCode'' by Daniel Madzia and colleagues in 2021 as "the largest clade containing '' Igua ...

ident. * ?

Nodosauridae Nodosauridae is a family of ankylosaurian dinosaurs known from the Late Jurassic to the Late Cretaceous periods in what is now Asia, Europe, North America, and possibly South America. While traditionally regarded as a monophyletic clade as the ...

ident. (identified as Deinodontidae) * ''

'' ''

'' sp. *

Ornithischia Ornithischia () is an extinct clade of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek ...

ident. * ''Amia'' sp.Hodnett, J.-P. M., Tweet, J. S. and Santucci, V. L., (2022), The occurrence of fossil cartilaginous fishes (Chondrichthyes) within the parks and monuments of the National Park Service: ''New Mexico Museum of Natural History and Science, Bulletin'' 90, p. 183-208 *

Crocodylidae Crocodiles (family Crocodylidae) or true crocodiles are large, semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term "crocodile" is sometimes used more loosely to include all extant membe ...

ident.

Footnotes

References

* Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. . Geologic formations of Wyoming Maastrichtian Stage of North America Cretaceous geology of Wyoming Yellowstone National Park {{US-geologic-formation-stub

Discovery of the first dinosaur found in Yellowstone

Paleofauna

See also

Footnotes

References