Arsinoitherium | |
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A. zitteli cast, Natural History Museum, London | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | † Embrithopoda |
Family: | † Arsinoitheriidae |
Genus: | † Arsinoitherium Beadnell 1902 |
Type species | |
Arsinoitherium zitteli (Beadnell, 1902) | |
Species | |
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Arsinoitherium is an extinct genus of paenungulate mammals belonging to the extinct order Embrithopoda. It is related to elephants, sirenians, and hyraxes. Arsinoitheres were superficially rhinoceros-like herbivores that lived during the Late Eocene and the Early Oligocene of North Africa from 36 to 30 million years ago, in areas of tropical rainforest and at the margin of mangrove swamps. A species described in 2004, A. giganteum, lived in Ethiopia about 27 million years ago.
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. [1] While the Faiyum Oasis is the only site where complete skeletons of Arsinoitherium fossils were recovered, arsinoitheriids have been found in southeastern Europe, including Crivadiatherium from Romania, and Hypsamasia and Palaeoamasia from Turkey.
The generic name Arsinoitherium comes from Pharaoh Arsinoe II (after whom the Faiyum Oasis, the region in which the first fossils were found, was called during the Ptolemaic Kingdom), [2] and the Ancient Greek : θηρίονtheríon "beast". The species epithet 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. [3]
Adults of the species A. zitteli stood around 1.75 m (5.7 ft) tall at the shoulders and 3 m (9.8 ft) in length. [4] [5] It weighed 2.5 tons, only slightly smaller than the modern white rhino and due to the similar features and sizes, Arsinoitherium is commonly thought[ by whom? ] to be an extinct rhinoceros species, but it is not closely related to rhinos; instead, their closest extant relatives are elephants and manatees. They were massive, slow-moving animals with forelimbs adapted for pulling strongly backwards 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. [6]
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. [7] [8] 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. [9] 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. [10] The skeleton is robust and the limbs were columnar, similar to those of elephants; the hips were also elephant-like, [4] 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. [11]
Fossils of Arsinoitherium have been found in: [12]
Moeritherium is an extinct genus of basal proboscideans from the Eocene of North and West Africa. It was related to elephants and, more distantly, to sea cows and hyraxes.
Aegyptopithecus is an early fossil catarrhine that predates the divergence between hominoids (apes) and cercopithecids. It is known from a single species, Aegyptopithecus zeuxis, which lived around 38-29.5 million years ago in the early part of the Oligocene epoch. It likely resembled modern-day New World monkeys, and was about the same size as a modern howler monkey, which is about 56 to 92 cm long. Aegyptopithecus fossils have been found in the Jebel Qatrani Formation of modern-day Egypt. Aegyptopithecus is believed to be a stem-catarrhine, a crucial link between Eocene and Miocene fossils.
Deinotheriidae is a family of prehistoric elephant-like proboscideans that lived during the Cenozoic era, first appearing in Africa, then spreading across South Asia and Europe. During that time, they changed very little, apart from growing much larger in size; by the late Miocene, they had become the largest land animals of their time. Their most distinctive features were their lack of upper tusks and downward-curving tusks on the lower jaw.
Chilgatherium is the earliest and most primitive representative of the family Deinotheriidae. It is known from late Oligocene fossil teeth found in the Ethiopian district of Chilga.
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 order is best known from its terminal member, the elephantine Arsinoitherium.
Arsinoitheriidae is a family of mammals belonging to the extinct order Embrithopoda. Remains have been found in the Middle East, Africa, Asia and Romania. When alive, they would have borne a strong but superficial resemblance to modern rhinoceroses; however, they were not closely related to them, instead being more closely related to hyraxes, elephants, sirenians, and possibly desmostylians.
Barytherium is a genus of an extinct family (Barytheriidae) of primitive proboscideans that lived during the late Eocene and early Oligocene in North Africa. The type species is Barytherium grave, found at the beginning of the 20th century in Fayum, Egypt. Since then, more complete specimens have been found at Dor el Talha, Libya. More fossils were also discovered in 2011 in the Aidum area in Dhofar by Oman's Ministry of Heritage and Culture, which was named Barytherium omansi.
Ptolemaiida is a taxon of wolf-sized afrothere mammals that lived in northern and eastern Africa during the Paleogene. The oldest fossils are from the latest Eocene strata of the Jebel Qatrani Formation, near the Fayum oasis in Egypt. A tooth is known from an Oligocene-aged stratum in Angola, and Miocene specimens are known from Kenya and Uganda.
Titanohyrax is an extinct genus of large to very large hyrax from the Eocene and Oligocene. Specimens have been discovered in modern-day Algeria, Tunisia, Egypt and Libya. Some species, like T. ultimus, are estimated to be as large as the modern rhinoceros. Titanohyrax species are still poorly known due to their rarity in the fossil record.
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, dating to the Ypresian. It has unique bilophodont upper molars, an embrithopod synapomorphy.
Eremopezus is a prehistoric bird genus, possibly a palaeognath. It is known only from the fossil remains of a single species, the huge and presumably flightless Eremopezus eocaenus. This was found in Upper Eocene Jebel Qatrani Formation deposits around the Qasr el Sagha escarpment, north of the Birket Qarun lake near Faiyum in Egypt. The rocks its fossils occur in were deposited in the Priabonian, with the oldest dating back to about 36 million years ago (Ma) and the youngest not less than about 33 Ma.
Eogavialis is an extinct genus of eusuchian crocodylomorph, usually regarded as a gavialoid crocodylian. It superficially resembles Tomistoma schlegelii, the extant false gharial, and consequently material from the genus was originally referred to Tomistoma. Indeed, it was not until 1982 that the name Eogavialis was constructed after it was realised that the specimens were from a more basal form.
The Jebel Qatrani Formation is a geologic formation located in the Faiyum Governorate of central Egypt. It is exposed between the Jebel Qatrani escarpment and the Qasr el Sagha escarpment, north of Birket Qarun lake near Faiyum. The formation conformably overlies the Qasr el Sagha Formation and is topped by the Widan el Faras Basalt. The age of the formation has been subject to debate, but the most recent research indicates that it covers both the latest parts of the Eocene and the Early Oligocene, spanning over the boundary between these two time periods.
Egypt has many fossil-bearing geologic formations, in which many dinosaurs have been discovered.
Saadanius is a genus of fossil primates dating to the Oligocene that is closely related to the common ancestor of the Old World monkeys and apes, collectively known as catarrhines. It is represented by a single species, Saadanius hijazensis, which is known only from a single partial skull tentatively dated between 29 and 28 million years ago. It was discovered in 2009 in western Saudi Arabia near Mecca and was first described in 2010 after comparison with both living and fossil catarrhines.
Sinopa is an extinct genus of placental mammals from extinct family Sinopidae within extinct order Hyaenodonta, that lived in North America and Asia from the early to middle Eocene.
Palaeoamasiidae or Palaeoamasinae is an extinct taxon of embrithopod mammals that have been found in Romania and Anatolia where they lived on the shores of the Tethys Ocean.
Ptolemaia is a genus of extinct Afrotherian mammals from the Oligocene of East Africa. The genus and type species, P. lyonsi, was described by Henry Fairfield Osborn in 1908 from the Jebel Qatrani Formation of Egypts' Fayum Depression. The genus name alludes to the Ptolemaic dynasty of Ancient Greece which ruled over the Egyptian region where Ptolemaia was discovered, while the specific epithet lyonsi honors H. G. Lyons, then director of the Egyptian Geological Survey. A second species, P. grangeri, was described in 1987, and named after the early 20th century paleontologist Walter W. Granger. Fossils of P. grangeri are also known from Kenya.
Megalohyrax is an extinct hyrax-grouped genus of herbivorous mammal that lived during the Oligocene, about 33-30 million years ago. Its fossils have been found in Africa and in Asia Minor.
The Fayyum is a region and an important fossil Lagerstätte in northern Egypt. The region comprises the Fayyum Basin, which is intensively used for agriculture, and adjoining areas; the important areas of discovery are mostly north and west of Lake Qarun. The Wadi al-Hitan, known for its numerous whale fossils and since 2005 UNESCO World Natural Heritage Site, forms the south-western end. The deposits of the Fayyum belong to various geological formations. They are mainly composed of limestone, siltstone and sandstone. The lower sections consist of marine sediments, while the upper, continental sediments were formed in a coastal landscape. The formation period ranges from the Middle to the Upper Eocene to the Lower Oligocene, which corresponds to an age of around 41 to 28 million years ago. The entire sedimentary complex is overlain by basalt, which dates back to volcanic activity around 24 million years ago.
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