''Embolotherium'' (Greek , + , "battering ram beast", or "wedge beast") is an extinct

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 ...

brontothere Brontotheriidae is a family of extinct mammals belonging to the order Perissodactyla, the order that includes horses, rhinoceroses, and tapirs. Superficially, they looked rather like rhinos, although they were actually more closely related to ...

that lived in

Mongolia Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, ...

during the late

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

epoch. It is most easily recognized by a large bony protuberance emanating from the anterior (front) of the skull. This resembles a

battering ram A battering ram is a siege engine that originated in ancient history, ancient times and was designed to break open the masonry walls of fortifications or splinter their wooden gates. In its simplest form, a battering ram is just a large, hea ...

, hence the name ''Embolotherium''. The animal is known from about 12

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

s, several

jaw The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

s, and a variety of other skeletal elements from the Ulan Gochu formation of

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for a ...

and the Irgilin Dzo of

Outer Mongolia Outer Mongolia was the name of a territory in the Manchu-led Qing dynasty of China from 1691 to 1911. It corresponds to the modern-day independent state of Mongolia and the Russian republic of Tuva. The historical region gained ''de facto' ...

Taxonomy

Several

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 ...

of ''Embolotherium'' have been named, including ''Embolotherium andrewsi'', ''Embolotherium grangeri'', ''Embolotherium louksi'', ''Embolotherium ultimum'', ''Embolotherium ergilensi'', and ''Embolotherium efremovi''. However, only two species, ''Embolotherium andrewsi'' and ''Embolotherium grangeri'', appear to be valid. Other supposed species of ''Embolotherium'' are probably synonymous with these two species and were originally based on juvenile skulls, poorly preserved fossil material, or specimens that are not significantly different from either ''E. andrewsi'' or ''E. grangeri''. Embolotherium andrewsi

Another genus of brontothere, ''Titanodectes'', which was named for several lower jaws found in the same sedimentary deposits as ''Embolotherium'', probably represents the same beast as ''Embolotherium grangeri''. '' Protembolotherium'' is another closely related genus from the Middle Eocene, which is distinguished by a noticeably smaller ram.

Description

Embolotherium-Tianjin Natural History Museum

Complete skeletons of ''Embolotherium'' have not yet been recovered. Based on the size its skull, up to 94 cm in greatest length, it was estimated to exceed the largest north american brontotheres in size. The latter having an estimated shoulder height of 8 feet and mass of at least 2800 kg. Unlike many of the other Late Eocene brontotheres, there is no clear evidence that ''Embolotherium'' was

sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

. All known specimens have large rams. Therefore, coupled with the fact that the rams were hollow and fragile in comparison to the solid and sturdy horns of the North American brontotheres, such as ''

Megacerops ''Megacerops'' ("large-horned face", from '' méga-'' "large" + '' kéras'' "horn" + '' ōps'' "face") is an extinct genus of the prehistoric odd-toed ungulate (hoofed mammal) family Brontotheriidae, an extinct group of rhinoceros-like browsers ...

'', it does not seem likely that the ram served as a weapon for contests between males. Rather, it might have had a non-sexual function, such as signaling to each other. The ram may have served as a specialized

resonator A resonator is a device or system that exhibits resonance or resonant behavior. That is, it naturally oscillates with greater amplitude at some frequencies, called resonant frequencies, than at other frequencies. The oscillations in a resonator ...

for sound production. This hypothesis is suggested by the fact that the bony

nasal cavity The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal c ...

extends to the peak of the ram, thus implying that the nasal chamber was greatly elevated, possibly creating a resonating chamber.

References

* Barry Cox, Colin Harrison, R.J.G. Savage, and Brian Gardiner. (1999): The Simon & Schuster Encyclopedia of Dinosaurs and Prehistoric Creatures: A Visual Who's Who of Prehistoric Life.

Simon & Schuster Simon & Schuster () is an American publishing company and a subsidiary of Paramount Global. It was founded in New York City on January 2, 1924 by Richard L. Simon and M. Lincoln Schuster. As of 2016, Simon & Schuster was the third largest publ ...

. * David Norman. (2001): The Big Book of Dinosaurs. page 204, Walcome books.

External links

BBC Online

{{Taxonbar, from=Q133204 Brontotheres Eocene mammals of Asia Fossils of China Taxa named by Henry Fairfield Osborn Brontotheres of Asia