''Arsinoitherium'' is an extinct genus of paenungulate

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur ...

s belonging to the extinct

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

Embrithopoda Embrithopoda ("heavy-footed") is an order of extinct mammals known from Asia, Africa and Eastern Europe. Most of the embrithopod genera are known exclusively from jaws and teeth dated from the late Paleocene to the late Eocene; however, the orde ...

. It is related to

elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantida ...

sirenia The Sirenia (), commonly referred to as sea-cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The Sirenia currently comprise two distinct ...

ns,

hyrax Hyraxes (), also called dassies, are small, thickset, herbivorous mammals in the order Hyracoidea. Hyraxes are well-furred, rotund animals with short tails. Typically, they measure between long and weigh between . They are superficially simila ...

es and the extinct

desmostylia The Desmostylia (from Greek δεσμά ''desma'', "bundle", and στῦλος ''stylos'', "pillar") are an extinct order of aquatic mammals that existed from the early Oligocene (Rupelian) to the late Miocene ( Tortonian) (). Desmostylians are t ...

ns. Arsinoitheres were superficially

rhinoceros A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct specie ...

-like

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

s that lived during the Late

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

and the Early

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but t ...

North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...

from 36 to 30 million years ago, in areas of

tropical rainforest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equator ...

and at the margin of

mangrove swamp Mangrove forests, also called mangrove swamps, mangrove thickets or mangals, are productive wetlands that occur in coastal intertidal zones. Mangrove forests grow mainly at tropical and subtropical latitudes because mangroves cannot withstand fre ...

s. A species described in 2004, ''A. giganteum'', lived in

Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...

about 27 million years ago.

Taxonomy

The best-known (and first-described) species is ''A. zitteli''. Another species, ''A. giganteum'', was discovered in the

n highlands of

Chilga Chilga (Amharic: ጭልጋ ''č̣ilgā'') also Chelga, Ch'ilga is a woreda in Amhara Region, Ethiopia. It is named after its chief town Chilga (also known as Ayikel), an important stopping point on the historic Gondar- Sudan trade route. Part o ...

in 2003. The fossil teeth, far larger than those of ''A. zitteli'', date to around 28–27 million years ago. While the Fayum Oasis is the only site where complete skeletons of ''Arsinoitherium'' fossils were recovered, arsinoitheriids have been found in southeastern Europe, including ''

Crivadiatherium ''Crivadiatherium'' is an extinct genus of Palaeoamasiidae, which fossil remains—teeth and mandible fragments—have been discovered in the Crivadia site in the Hațeg depression, Romania. The age of the Crivadia site is not clear, but se ...

'' from Romania, and ''

Hypsamasia ''Hypsamasia'' is an extinct embrithopod mammal that lived during the middle Eocene. Dental remains of this herbivore have been found in the Kartal Formation near the village Saribeylar (, paleocoordinates ) north of Ankara in what is today ...

'' and ''

Palaeoamasia ''Palaeoamasia'' is an extinct herbivorous paenungulate mammal of the embrithopod order, making it distantly related to elephants, sirenians, and hyraxes. ''Palaeoamasia'' fossils have been found in Turkish deposits of the Çeltek Formation, d ...

'' from Turkey. The

generic Generic or generics may refer to: In business * Generic term, a common name used for a range or class of similar things not protected by trademark * Generic brand, a brand for a product that does not have an associated brand or trademark, other ...

name ''Arsinoitherium'' comes from

Pharaoh Pharaoh (, ; Egyptian: '' pr ꜥꜣ''; cop, , Pǝrro; Biblical Hebrew: ''Parʿō'') is the vernacular term often used by modern authors for the kings of ancient Egypt who ruled as monarchs from the First Dynasty (c. 3150 BC) until th ...

Arsinoe I (after whom the

Faiyum Oasis The Faiyum Oasis ( ar, واحة الفيوم ''Waḥet El Fayyum'') is a depression or basin in the desert immediately to the west of the Nile, or just 62 miles south of Cairo in Egypt. The extent of the basin area is estimated at between 1,270 ...

, the region in which the first fossils were found, was called during the Ptolemaic Kingdom), and the grc, θηρίον ''theríon'' "beast". The species epithet of the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specim ...

, ''A. zitteli'', was given to it in honor of the eminent German paleontologist Karl Alfred Ritter von Zittel, regarded by some as the pioneer of paleontology in Egypt.

Description

Adults of the species ''A. zitteli'' stood around tall at the shoulders and in length. They were massive, slow-moving animals with forelimbs adapted for pulling strongly backward rather than swinging forward, a feature typical of animals that punt themselves through shallow water or walk on soft, sticky ground. Fossils are found in sediments deposited in coastal swamps and warm, humid, heavily-vegetated lowland forests across what is now Africa and Arabia. The most noticeable features of ''Arsinoitherium'' were a pair of enormous horns above the nose and a second pair of tiny knob-like horns over the eyes. These were structurally similar to the horns of modern bovids. While reconstructions usually show them as similar to the ossicones of

giraffes The giraffe is a large African hoofed mammal belonging to the genus ''Giraffa''. It is the tallest living terrestrial animal and the largest ruminant on Earth. Traditionally, giraffes were thought to be one species, '' Giraffa camelopardal ...

, in life each bony core may have been covered, like the horn cores of bovids, with a large horn of

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up Scale (anatomy), scales, hair, Nail ...

. Both males and females had horns. While some investigators have described a larger and a smaller species from the same site, others have identified the difference in body and tooth size as sexual dimorphism. The skeleton is robust and the limbs were columnar, similar to those of elephants; the hips were also elephant-like, and arsinotheres were not built to run. ''Arsinoitherium'' had a full complement of 44 teeth, which is the primitive state of placental mammalian dentition. However, the genus had a unique and highly specialized way of chewing, shifting the jaw joint to produce constant pressure along its continuous row of teeth; it has been reconstructed as a highly selective browser.

Distribution

Fossils of ''Arsinoitherium'' have been found in:''Arsinoitherium''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was crea ...

.org ;Eocene * Aydim Formation,

Oman Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of ...

* Idam Unit Formation,

Libya Libya (; ar, ليبيا, Lībiyā), officially the State of Libya ( ar, دولة ليبيا, Dawlat Lībiyā), is a country in the Maghreb region in North Africa. It is bordered by the Mediterranean Sea to the north, Egypt to the east, Suda ...

* Djebel Chambi,

Tunisia ) , image_map = Tunisia location (orthographic projection).svg , map_caption = Location of Tunisia in northern Africa , image_map2 = , capital = Tunis , largest_city = capital , ...

;Oligocene * Malembe,

Angola , national_anthem = "Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordinat ...

Jebel Qatrani Formation The Jebel Qatrani Formation (also Gebel Qatrani) is a palaeontological and geologic formation located in the Faiyum Governorate of central Egypt. Conformably overlying the Qasr el Sagha Formation. It is exposed namely between the Jebel Qatran ...

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a List of transcontinental countries, transcontinental country spanning the North Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via a land bridg ...

* Chilga formation,

* Erageleit Formation,

Kenya ) , national_anthem = " Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

* Ashawq Formation, Oman * Shumaysi Formation,

Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the Ara ...

References

External links

New fossils from Ethiopia open a window on Africa's 'missing years'

Arsinoitherium fact file on ''BBC Science & Nature: Prehistoric LifeDescription of Arsinoitherium zitteli from upper Eocene strata in Egypt
* {{Taxonbar, from=Q131720 Embrithopods Prehistoric placental genera Priabonian genus first appearances Rupelian genus extinctions Eocene mammals of Africa Oligocene mammals of Africa Fossils of Angola Fossils of Egypt Fossils of Ethiopia Fossils of Kenya Fossils of Libya Fossils of Tunisia Eocene mammals of Asia Oligocene mammals of Asia Fossils of Oman Fossils of Saudi Arabia Fossil taxa described in 1902