''Deinodon'' (Greek for "terrible tooth") is a

dubious Doubt is a mental state in which the mind remains suspended between two or more contradictory propositions, unable to be certain of any of them. Doubt on an emotional level is indecision between belief and disbelief. It may involve uncertainty ...

tyrannosaurid 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 ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

containing a single

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, ''Deinodon horridus''. ''D. horridus'' is known only from a set of teeth found in the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger 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 ''creta'', the ...

Judith River Formation The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Judith River Group. It dates to the Late Cretaceous, between 79 and 75.3 million years ago, corresponding to the "Judithian" land vertebrate age. It ...

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...

and named by paleontologist

Joseph Leidy Joseph Mellick Leidy (September 9, 1823 – April 30, 1891) was an American paleontologist, parasitologist and anatomist. Leidy was professor of anatomy at the University of Pennsylvania, later was a professor of natural history at Swarthmore ...

in 1856.Leidy, J. (1856). "Notices of the remains of extinct reptiles and fishes, discovered by Dr. F.V. Hayden in the badlands of the Judith River, Nebraska Territory." ''Proc. Acad. Nat. Sci.'', 8(2): 72. These were the first tyrannosaurid remains to be described and had been collected by

Ferdinand Vandeveer Hayden Ferdinand Vandeveer Hayden (September 7, 1829 – December 22, 1887) was an American geologist noted for his pioneering surveying expeditions of the Rocky Mountains in the late 19th century. He was also a physician who served with the Union Ar ...

. The teeth of ''Deinodon'' were slightly heterodont, and the holotype of ''Aublysodon'' can probably be assigned to ''Deinodon''.

History and classification

It is likely that the fossilized teeth of ''D. horridus'' belonged to the dinosaur later identified as ''

Gorgosaurus libratus ''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 Ca ...

''. In a 1922 study,

William Diller Matthew William Diller Matthew Royal Society, FRS (February 19, 1871 – September 24, 1930) was a vertebrate paleontologist who worked primarily on mammal fossils, although he also published a few early papers on mineralogy, petrological geology, one on ...

Barnum Brown Barnum Brown (February 12, 1873 – February 5, 1963), commonly referred to as Mr. Bones, was an American paleontologist. Named after the circus showman P. T. Barnum, he discovered the first documented remains of ''Tyrannosaurus'' during a career ...

found that the teeth of ''D. horridus'' and ''G. libratus'' were indistinguishable from each other, and that they almost certainly belonged to the same species. However, because ''D. horridus'' was not yet known from any skeletal remains, they refrained from formally declaring them to be synonyms.Matthew, W.D. and Brown, B. (1922). "The family Deinodontidae, with notice of a new genus from the Cretaceous of Alberta." ''Bulletin of the American Museum of Natural History'', 46(6): 367-385. In a 1970 review,

Dale Russell Dale Alan Russell (27 December 1937 – 21 December 2019) was an American-Canadian geologist and palaeontologist. Throughout his career Russell worked as the Curator of Fossil Vertebrates at the Canadian Museum of Nature, Research Professor a ...

stated that because the teeth of ''D. horridus'' could not be distinguished from either ''G. libratus'' or his newly described species ''

Daspletosaurus torosus ''Daspletosaurus'' ( ; meaning "frightful lizard") is a genus of tyrannosaurid dinosaur that lived in Laramidia between about 79.5 and 74 million years ago, during the Late Cretaceous Period. The genus ''Daspletosaurus'' contains three species ...

'', it must be considered a ''nomen vanum'' ("empty name").Russell, D. (1970). "Tyrannosaurs from the Late Cretaceous of western Canada." ''National Museum of Natural Science Publications in Palaeontology'', 1: 1–34. Since Russell published his opinion, most researchers have regarded ''Deinodon'' as a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

'', though some have argued that since ''Deinodon'' and ''Gorgosaurus'' cannot be distinguished, they should be synonymized with ''D. horridus'' as the valid name for "''Gorgosaurus''" skeletons.Sahni, A. (1972). "The vertebrate fauna of the Judith River Formation, Montana." ''Bulletin of the AMNH'', 147(6). Additionally, several researchers have agreed that the genus ''

Aublysodon ''Aublysodon'' (“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 ...

'' (including the species ''A. mirandus'' and ''A. lateralis''), should also be considered a synonym of ''Deinodon'', since it is based on incisor teeth that likely come from the same animal. Lambe (1902) went further, and said that as originally named, ''Deinodon'' was not preoccupied, and instead, regarded ''Aublysodon'' as a ''nomen nudum''.

Description

''Deinodon'' is known from a few, slightly heterodont teeth. A few phalanges, and a metatarsal with fragments of others, were found to be possibly assignable to ''D. horridus'' by Lambe in 1902.

List of species and synonyms

Numerous species were referred to the genus ''Deinodon'' in the past. However, because most researchers now consider the genus and its type species ''nomina dubia'', any additional species referred to the genus cannot be supported.

References

{{Taxonbar, from=Q134788 Late Cretaceous dinosaurs of North America Tyrannosaurids Nomina dubia Fossil taxa described in 1856 Paleontology in Montana Campanian genus first appearances Campanian genus extinctions

History and classification

Description

List of species and synonyms

See also

References