Daspletosaurini is an extinct clade of

tyrannosaurine The tyrannosaurines (Tyrannosaurinae) is an extinct subfamily of Tyrannosauridae a family of coelurosaurian theropod dinosaurs that consists of at least three tribes and several genera. All fossils of these genera have been found in the Late Cret ...

dinosaurs that lived in

Laramidia Laramidia was an island continent that existed during the Late Cretaceous period (99.6–66 Ma), when the Western Interior Seaway split the continent of North America in two. In the Mesozoic era, Laramidia was an island land mass separated from A ...

during 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 ...

(Middle

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...

) period. It consists of two genera: ''

Daspletosaurus ''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 ...

'' and ''

Thanatotheristes ''Thanatotheristes'' (meaning "reaper of death" according to the original authors; literally, "death harvester" in Greek language, Greek: , , "Death" and , , "harvester") is a genus of tyrannosaurid dinosaur from the Late Cretaceous of Larami ...

''. Four species have been described in the two genera, namely ''Daspletosaurus torosus'', ''Daspletosaurus horneri'', ''Daspletosaurus wilsoni'', and ''Thanatotheristes degrootorum''. At one point all of them were assigned as specimens of ''D. torosus'', but several papers since 2017 have found them to represent distinct species. These studies found

anagenesis Anagenesis is the gradual evolution of a species that continues to exist as an interbreeding population. This contrasts with cladogenesis, which occurs when there is branching or splitting, leading to two or more lineages and resulting in separate ...

in the group, whether contained in a daspletosaurin clade or paraphyletic in respect to the linage of tyrannosaurines leading up to ''

Tyrannosaurus ''Tyrannosaurus'' is a genus of large theropoda, theropod dinosaur. The species ''Tyrannosaurus rex'' (''rex'' meaning "king" in Latin), often called ''T. rex'' or colloquially ''T-Rex'', is one of the best represented theropods. ''Tyrannosa ...

''.

Description

Daspletosaurins were large predators, reaching around in length. However, they were not the largest tyrannosaurids, as more derived taxa, such as ''

'', could reach lengths of more than . Daspletosaurini is diagnosed by characteristics such as the presence of an extremely coarse subcutaneous surface of the maxilla anteroventral to the antorbital fossa; a constricted jugal ramus of maxilla; the anteroventral corner of the maxilla tapers into a shallow angle (<65°) as measured between the alveolar margin of the first two alveoli and the anterior margin of the subcutaneous surface; a prefrontal that is broad in dorsal view and strongly dorsomedially arced in anterior view; a dentary chin located ventral to either the third alveolus or third interdental plate and possessing no fewer than 14 maxillary teeth.

Classification

In the 2020

description Description is the pattern of narrative development that aims to make vivid a place, object, character, or group. Description is one of four rhetorical modes (also known as ''modes of discourse''), along with exposition, argumentation, and narr ...

of ''

'', Voris ''et al''. erected Daspletosaurini as a new clade within Tyrannosauridae, as a sister taxon to a clade comprising ''

Zhuchengtyrannus ''Zhuchengtyrannus'' (meaning "Zhucheng tyrant") is a genus of tyrannosaurid theropod dinosaur known from the Campanian stage of the Late Cretaceous of Shandong Province, China. It belongs to the subfamily Tyrannosaurinae, and contains a single s ...

'', ''

Tarbosaurus ''Tarbosaurus'' ( ; meaning "alarming lizard") is a genus of tyrannosaurid dinosaur that flourished in Asia about 70 million years ago, at the end of the Late Cretaceous Period, considered to contain a single known species, ''Tarbosaurus bataa ...

'', and ''

''. The

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

below shows the results of the

phylogenetic analyses In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

performed by Voris ''et al.'' (2020): In 2022, Warshaw & Fowler proposed that the three ''Daspletosaurus'' species evolved through

in the Tyrannosaurinae in a line leading to ''Zhuchengtyrannus'', ''Tarbosaurus'', and ''Tyrannosaurus''. Due to their more fragmentary nature, ''Thanatotheristes'' and ''Nanuqsaurus'' were excluded from this analysis. The cladogram below shows the results of the phylogenetic analysis performed by Warshaw & Fowler (2022).

References

{{Taxonbar, from=Q17620750 Tyrannosaurs