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''Arsinoitherium'' is an extinct genus of
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, in life each bony core may have been covered, like the horn cores of bovids, with a large horn of keratin. 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.
Fossils of ''Arsinoitherium'' have been found in:''Arsinoitherium''
at
;Eocene
* Aydim Formation, Oman
*
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
paenungulate
Paenungulata (from Latin ''paene'' "almost" + ''ungulātus'' "having hoofs") is a clade of "sub-ungulates", which groups three extant mammal orders: Proboscidea (including elephants), Sirenia (sea cows, including dugongs and manatees), and Hyraco ...
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 or ...
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 d ...
Embrithopoda. It is related to elephants, sirenians, 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 simil ...
es and the extinct desmostylians. Arsinoitheres were superficially rhinoceros-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 mouthpart ...
s that lived during the Late Eocene 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 the ...
of North Africa from 36 to 30 million years ago, in areas of tropical rainforest 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 about 27 million years ago.
Taxonomy
The best-known (and first-described) species is ''A. zitteli''. Another species, ''A. giganteum'', was discovered in the Ethiopian highlands of Chilga 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 seems t ...
'' 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 An ...
'' 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 name ''Arsinoitherium'' comes from Pharaoh Arsinoe I (after whom the Faiyum Oasis, the region in which the first fossils were found, was called during the Ptolemaic Kingdom), and the grc, θηρίον ''theríon'' "beast". The species epithet Specific name may refer to:
* in Database management systems, a system-assigned name that is unique within a particular database
In taxonomy, either of these two meanings, each with its own set of rules:
* Specific name (botany)
A botanical name ...
of the type species, ''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, in life each bony core may have been covered, like the horn cores of bovids, with a large horn of keratin. 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:at
Fossilworks
Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database
The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...
.orgIdam Unit Formation
Idam (Tamil) (Sanskrit: इदम् or अयम् or इयम्) is a Tamil/Sanskrit word which denotes location or position or place. In grammar it is used at the beginning or middle of a sentence as a nominative or attributive pronoun, com ...
, Libya
* Djebel Chambi
: ''For mountains or other uses, see: Jabal.''
Djebel (1937–1958) was a French Thoroughbred racehorse, who won 15 of 22 races during 1939–1942 including the Prix d'Essai, 2000 Guineas and Prix de l'Arc de Triomphe. He was later a leading sir ...
, Tunisia
;Oligocene
* Malembe, Angola
* 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 Qat ...
, Egypt
* Chilga formation
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 of th ...
, Ethiopia
* Erageleit Formation, Kenya
* Ashawq Formation, Oman
* Shumaysi Formation, Saudi Arabia
References
External links
New fossils from Ethiopia open a window on Africa's 'missing years'
Arsinoitherium fact file on ''BBC Science & Nature: Prehistoric Life
* {{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