Gnathotitan

Gnathotitan; Temporal range: Middle Eocene (Irdinmanhan), Da. S T Ypr. Lut. B Pr. Rup. Ch.
	Holotype of G. berkeyi
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Infraclass:	Placentalia
Order:	Perissodactyla
Family:	†Brontotheriidae
Subfamily:	†Brontotheriinae
Tribe:	†Brontotheriini
Subtribe:	†Brontotheriina
Infratribe:	†Embolotheriita
Genus:	†Gnathotitan; Granger & Gregory, 1943
Species
	G. berkeyi (Granger & Gregory, 1943);

Gnathotitan is an extinct genus of horned brontothere that lived in East Asia during the Middle Eocene, in the Irdinmanhan land mammal age.^[1] A single species is known, G. berkeyi, known from Inner Mongolia, China.^[3]^[1]

Description

The jaw of Gnathotitan was remarkably large for a brontothere, with the lower jaw measuring 800 millimeters from the end of the jaw to the incisive border. The jaw is incredibly deep, and the molars are significantly larger than other brontotheres. The tips of the canine teeth are recurved, whilst the incisors are spoon-shaped. The horns are not present in any specimens, but it is inferred that they possessed them.^[3]^[1] The postcrania of Gnathotitan are unknown, but close relatives have a rather stout build similar to Teleoceras and Toxodon.^[4]

Classification

It has been hypothesized the related genus Sphenocoelus was ancestral to Gnathotitan historically,^[3] but recent phylogenies do not support this.^[1] Currently, the genus is placed within the infratribe Embolotheriita.^[1]^[4] Currently, Gnathotitan is considered a sister taxon to Pollyosbornia.^[1]

Cladogram after Mihlbachler (2008)^[1];

Embolotheriita

Aktautitan

	Pollyosbornia

	Gnathotitan

Pygmaetitan

	Brachydiastematherium

	Metatitan

Nasamplus

	Protembolotherium

	Embolotherium

References

1 2 3 4 5 6 7 8 Mihlbachler, Matthew Christian (2008). "Species taxonomy, phylogeny and biogeography of the Brontotheriidae (Mammalia, Perissodactyla) ; Bulletin of the American Museum of Natural History, no. 311". American Museum of Natural History. doi:10.1206/0003-0090(2008)501[1:STPABO]2.0.CO;2.
↑ Bai, Bin; Meng, Jin; Janis, Christine M.; Zhang, Zhao-Qun; Wang, Yuan-Qing (2020). "Perissodactyl diversities and responses to climate changes as reflected by dental homogeneity during the Cenozoic in Asia". Ecology and Evolution. 10 (13): 6333–6355. Bibcode:2020EcoEv..10.6333B. doi:10.1002/ece3.6363. ISSN 2045-7758. PMC 7381588. PMID 32724516.
1 2 3 Granger, Walter; Gregory, William K. "A revision of the Mongolian titanotheres. Bulletin of the AMNH ; v. 80, article 10". Biodiversity Heritage Library. Retrieved 2025-10-10.
1 2 Mihlbachler, Matthew C.; Mihlbachler, Matthew C.; Lucas, Spencer G.; Emry, Robert J.; Bayshashov, Bolat (2004). A new brontothere (Brontotheriidae, Perissodactyla, Mammalia) from the Eocene of the Ily Basin of Kazakstan and a phylogeny of Asian "horned" brontotheres. New York, NY: American Museum of Natural History.

[:1-1] 1 2 3 4 5 6 7 8 Mihlbachler, Matthew Christian (2008). "Species taxonomy, phylogeny and biogeography of the Brontotheriidae (Mammalia, Perissodactyla) ; Bulletin of the American Museum of Natural History, no. 311". American Museum of Natural History. doi:10.1206/0003-0090(2008)501[1:STPABO]2.0.CO;2.

[Bai-2020-2] Bai, Bin; Meng, Jin; Janis, Christine M.; Zhang, Zhao-Qun; Wang, Yuan-Qing (2020). "Perissodactyl diversities and responses to climate changes as reflected by dental homogeneity during the Cenozoic in Asia". Ecology and Evolution. 10 (13): 6333–6355. Bibcode:2020EcoEv..10.6333B. doi:10.1002/ece3.6363. ISSN 2045-7758. PMC 7381588. PMID 32724516.

[:0-3] 1 2 3 Granger, Walter; Gregory, William K. "A revision of the Mongolian titanotheres. Bulletin of the AMNH ; v. 80, article 10". Biodiversity Heritage Library. Retrieved 2025-10-10.

[:2-4] 1 2 Mihlbachler, Matthew C.; Mihlbachler, Matthew C.; Lucas, Spencer G.; Emry, Robert J.; Bayshashov, Bolat (2004). A new brontothere (Brontotheriidae, Perissodactyla, Mammalia) from the Eocene of the Ily Basin of Kazakstan and a phylogeny of Asian "horned" brontotheres. New York, NY: American Museum of Natural History.

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