Deinodon Temporal range:Late Cretaceous,77 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Lectotype tooth ofD. horridus (specimen ASNP 9534)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Family:	†Tyrannosauridae
Subfamily:	†Deinodontinae Cope, 1866 emend Brown, 1914 sensu Matthew and Brown, 1922
Genus:	†Deinodon Leidy, 1856
Type species
†Deinodon horridus Leidy, 1856
Synonyms
Megalosaurus horridus(Leidy, 1856) Leidy, 1857 Aublysodon horridus(Leidy, 1856) Cope, 1868 Aublysodon lateralisCope, 1876[citation needed] Dryptosaurus kenabekidesHay, 1899 Deinodon lateralis(Cope, 1876) Hay, 1902[citation needed] Deinodon kenabekides(Hay, 1899) Olshevsky, 1995

Deinodon (Greek for "terrible tooth") is adubioustyrannosauriddinosaurgenus containing a singlespecies,Deinodon horridus.D. horridus is known only from a set of teeth found in theLate CretaceousJudith River Formation ofMontana and named by paleontologistJoseph Leidy in 1856.^[1] These were the first tyrannosaurid remains to be described and had been collected byFerdinand Vandeveer Hayden.^[1] The teeth ofDeinodon were slightly heterodont, and the holotype ofAublysodon can probably be assigned toDeinodon.^[2]

It is likely that the fossilized teeth ofD. horridus belonged to the dinosaur later identified asGorgosaurus libratus. In a 1922 study,William Diller Matthew &Barnum Brown found that the teeth ofD. horridus andG. libratus were indistinguishable from each other, and that they almost certainly belonged to the same species. However, becauseD. horridus was not yet known from any skeletal remains, they refrained from formally declaring them to be synonyms.^[3][4] In a 1970 review,Dale Russell stated that because the teeth ofD. horridus could not be distinguished from eitherG. libratus or his newly described speciesDaspletosaurus torosus, it must be considered anomen vanum ("empty name").^[5] Since Russell published his opinion, most researchers have regardedDeinodon as anomen dubium,^[4] though some have argued that sinceDeinodon andGorgosaurus cannot be distinguished, they should be synonymized withD. horridus as the valid name for "Gorgosaurus" skeletons.^[6] Additionally, several researchers have agreed that the genusAublysodon (including the speciesA. mirandus andA. lateralis), should also be considered a synonym ofDeinodon, since it is based on incisor teeth that likely come from the same animal.^[2][3][6] Lambe (1902) went further, and said that as originally named,Deinodon was not preoccupied, and instead, regardedAublysodon as anomen nudum.^[2]

Deinodon is known from a few, slightly heterodont teeth.^[2]

A few phalanges, and a metatarsal with fragments of others, were found to be possibly assignable toD. horridus by Lambe in 1902.^[2]

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

• Timeline of tyrannosaur research

• Late Cretaceous dinosaurs of North America
• Tyrannosauridae
• Nomina dubia
• Fossil taxa described in 1856
• Paleontology in Montana
• Campanian genus first appearances
• Campanian genus extinctions

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