Brachydiastematherium

Brachydiastematherium Temporal range: Late Eocene–Late Eocene PreꞒ Ꞓ O S D C P T J K Pg N ↓
Holotype of B. transylvanicum.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Perissodactyla
Family:	† Brontotheriidae
Genus:	† Brachydiastematherium Böckh & Matyasovski, 1876
Species:	†B. transylvanicum
Binomial name
†Brachydiastematherium transylvanicum Böckh & Matyasovski, 1876

Brachydiastematherium (literally "short diastema beast") is a genus of Eocene brontotheriid. It is the westernmost species of brontothere, with the first fossils of it being found in Transylvania, Romania. Only the type species, B. transylvanicum, is known. ^[1]

Description

In comparison with other brontothere fossils, it is suggested that B. transylvanicum would have had an elongated head, not unlike Dolichorhinus , and be about 2 meters at the withers (anatomically speaking, the highest part of the back at the base of the neck). ^{[2] [3]} The name of Brachydiastematherium comes from the fact that the genus lacks a large diastema (tooth gap) between the canines and the premolars. This trait is shared by another genus, Metatitan , which also shares the unique trait of a molariform metaconid. ^[4]

Phylogeny

Most phylogenies support the idea that Brachydiastematherium is closest to Metatitan among the embolotheres, due to aforementioned morphological similarity in dental structure. ^[4]

Cladogram after Mihlbachler (2008): ^[5]

Embolotheriita	Aktautitan Pollyosbornia Gnathotitan Pygmaetitan Brachydiastematherium Metatitan Nasamplus Protembolotherium Embolotherium

References

1. "Prohyracodon orientale Koch, the oldest known true rhinoceros. American Museum novitates ; no. 395". digitallibrary.amnh.org. Retrieved 2025-10-06.
2. Spencer George Lucas und Robert M. Schoch: European Brontotheres. In: Donald R. Prothero und Robert M. Schoch (Hrsg.): The evolution of perissodactyls. New York und London, 1989, S. 485–489
3. Cristina Fărcas: Study of the Upper Eocene-Lower Oligocene continental formations from northwestern side of Transylvanian Depression - Biostratigraphy, and palaeoenvironmental reconstructions based on land vertebrates. Babeș-Bolyai-Universität, Cluj-Napoca, 2011
4. "A new brontothere (Brontotheriidae, Perissodactyla, Mammalia) from the Eocene of the Ily Basin of Kazakstan and a phylogeny of Asian "horned" brontotheres. American Museum novitates ; no. 3439". digitallibrary.amnh.org. Retrieved 2025-10-06.
5. Matthew C. Mihlbachler: Species taxonomy, phylogeny, and biogeography of the Brontotheriidae (Mammalia: Perissodactyla). Bulletin of the American Museum of Natural History 311, 2008, ISSN 0003-0090, S. 1–475.