Arsinoitherium

from Wikipedia, the free encyclopedia
Arsinoitherium
Skeleton of Arsinoitherium zitteli in the Natural History Museum.

Skeleton of Arsinoitherium zitteli in the Natural History Museum .

Temporal occurrence
Upper Eocene to Oligocene
41 to 24 million years
Locations
Systematics
Afrotheria
Paenungulata
Tethytheria
Embrithopoda
Arsinoitheriidae
Arsinoitherium
Scientific name
Arsinoitherium
Beadnell , 1902

Arsinoitherium is an extinct genus of African mammals ( Afrotheria ), which are placed in the order of the Embrithopoda . These are a little-known group closely related to the manatees and elephants that were foundin Africa, the Arabian Peninsula, and western Eurasia from the Paleocene to the Oligocene . Arsinoitherium represents an animal the size of a rhinoceros, which was characterized by two pairs of horns made of bone substance on the skull, the front of which reached extremely large dimensions and whose function has not yet been clarified. Also typical were very high molars and a complete set of teeth without interruption in the row of teeth. The rather poorly developed basin area indicates that the animals probably lived on the edges of swamps and lakes and ate plant-based food. Overall, Arsinoitherium is the best-studied representative of the Embrithopoda, extensive finds come largely from the Fayyum in Egypt and dated in the Upper Eocene and Lower Oligocene around 40 to 30 million years ago. However, other fossil remains are documented from large parts of Africa.

description

Habitus

Arsinoitherium represented a large mammal and had a rhinoceros-like habit : it had a massive, cylindrical body with a short neck and had strong, short and columnar legs, each with five short toes ( pentadactyl ). The shoulder height was about 1.8 m with a head-trunk length of more than 3.4 m. The live weight is estimated at 1.5 to 1.9 t for smaller forms and up to 2.4 t for larger forms. Other authors assume up to 4 t.

Skull and dentition features

Arsinoitherium skull

The massive skull reached 74 to 77 cm in length, measured to the tip of the horns up to 109 cm. The cheekbones , however, were not very expansive and were about 32 to 33 cm apart. The occiput was also very strong, with two widely spaced and strongly protruding articular surfaces at the base of the cervical spine. The parietal bones were rather short and clearly saddled in the longitudinal profile. The frontal bone , which formed the base of the horns, was attached to this . The orbit was relatively far back in the skull, behind the last molar. The front part of the rostrum was rather short and low, at the base of the front horns a small, arched remnant of the nasal bone was attached, which in older animals was fused with the middle jawbone and which formed the two large nostrils on the front of the large pair of horns separated. The median jawbone was clearly elongated backwards and touched the frontal bone, a feature that also occurs in the proboscis and manatees . Due to the extremely high molars, the upper jaw protruded high.

The lower jaw, between 53 and 73 cm long, was slender in relation to the massive teeth with a low bone body about 11 cm high on the posterior molar. However, it had strong and protruding joint ends, the crown process rose up to 44 cm above the base of the lower jaw. The symphysis reached to the anterior molar and was therefore very strong. The set of teeth consisted of the complete set of teeth of the early mammals and thus had the following tooth formula : In general, the entire row of teeth was closed and no diastema formed. The incisors were nail-like in shape and were rather small. An exception here is the inner pair, which was sometimes slightly enlarged, a feature that was already pronounced in the earliest representatives of the Embrithopoda. the canine resembled the incisors, which is known as incisiform . The premolars were simply built and narrow and hardly molarized, so they differed significantly from the rear molars. These had two clearly transverse, protruding enamel ridges ( bilophodont ) on the chewing surface and were very large. This allowed the posterior molars to be 8 to 9 cm long. Overall, what was remarkable about the molars was their pronounced high crown ( hypsodontal ). The premolars reached a height of up to 7 cm, the rearmost and most massive molar, on the other hand, could be up to 13 cm high. The entire row of teeth from the second premolar to the last molar was up to 28 cm in length.

horns

The horns were the most outwardly striking feature of Arsinoitherium , of which it possessed two pairs. In contrast to similar formations of modern mammals, these did not consist of keratin or horny substance , but represented bony formations. The foremost and largest pair dominated the facial area and was formed entirely from the nasal bone. The individual horns could easily be up to 60 cm long, in large individuals the horn tips were up to 72 cm above the snout. From the base, which for each horn measured up to 22 cm in the longitudinal direction and up to 15 cm in width, they protruded upwards at an angle, the tips were up to 37 cm apart. The horns mostly had a triangular cross-section with the tip pointing forward. They had evolved through the gaping apart of the upper and lower bony walls of the nasal bone and were thus pervaded by numerous cavities. Since these continuously merged into the paranasal sinuses and the frontal sinuses , the horns can in principle be regarded as hollow. Inside there was a system of supporting struts, but the outer horn wall only reached a maximum thickness of 5 mm in some places. At the base of this mighty pair of horns, still on the frontal bone and just above the orbit , sat the much smaller, rear pair of horns, which was formed entirely from this skull bone.

Features of the body skeleton

The postcranial skeleton is known from numerous finds, but the spine has not been passed on in full. In contrast to similarly large mammals, the shoulder blade was not elongated, but markedly broadened and short. The humerus was particularly massive, up to 61 cm long and greatly narrowed in front and behind. It had a prominent bony elevation on the shaft that served as the insertion of the deltoid muscle . The ulna , which reached a length of 50 cm, was not connected to the rather flat and short radius . The largest long bone was the thigh bone with over 80 cm in length, it clearly exceeded the shin , which was only half as long. However, the head of the femur was noticeably close to the shaft, while the front and back were characteristically narrowed. Both fore and hind feet had five rays ( pentadactyl ) and were shaped similarly to today's elephants , but it is likely that Arsinoitherium exercised a clearer plantigrade locomotion ( sole walkers ) and the toes were more widely spread. Additionally developed joint surfaces in the carpal and tarsal area enabled a very high flexibility of both the front and rear feet. Analogous to the elephants, the carpal and tarsal bones were arranged in series, that is, the individual bone elements in a row lay directly behind one another and did not overlap one another as is the case with numerous other ungulates.

Locations

Finds of arsinoitherium come from both Africa and the Arabian Peninsula , which were connected during the Eocene and Oligocene . The most important remains, which also served to first describe the genus, were found in the Fayyum in Egypt . This is located on the western side of the Nile around 80 km south of Cairo . The finds come from the Gebel-Qatrani Formation , a geological rock unit almost 350 m thick, consisting of sand , silt and clay stones as well as conglomerates with an age of around 31 million years. Numerous finds have been made here since 1901; during the Fayum expedition of the American Museum in 1907, under the direction of Henry Fairfield Osborn , six complete skulls of arsinoitherium were discovered, one of which, the largest, was destroyed during transport. The year before, the German and Austrian researchers Eberhard Fraas and Richard Markgraf found numerous well-preserved Arsinoitherium fossils in the Fayyum. In total, remains of at least 47 individuals are known from the Fayyum, of which more than half belong to not fully grown, i.e. juvenile animals. It is not clear why so many young arsinoitherium are found here. Further bone and tooth remains came to light in Chilga in Ethiopia , which mainly comprise teeth, but also the bony remains of the horns and which are between 27 and 28 million years old. Individual teeth in particular are known from Dor el Talha in Libya and Malembe in Angola . The northernmost finds in Africa include those from Bir Om Ali in the Djebel Chambi in central Tunisia , which were located in a layer of silts and clays from the Upper Eocene. These are represented by tooth remnants (including a canine tooth) and postcranial skeletal elements such as vertebrae, foot bones and parts of the pelvis. A fragment of the upper jaw with attached molars represents the most recent finds on the African continent. It comes from Lothidok in northwestern Kenya and is between 27 and 24 million years old. Remnants of the musculoskeletal system could also be found in the Aydim formation in southwest Oman . The allocation is somewhat questionable, but clear teeth of the genus are known from the region. Other finds from the Arabian Peninsula come from Shumaysi in the west of Saudi Arabia .

Paleobiology

Way of life

Life picture of Arsinoitherium zitteli

Arsinoitherium was a massively built herbivore, its entire musculoskeletal system showed adjustments to a clumsy gait. Above all, this includes the thigh bone, which is greatly elongated compared to the shin, with a resulting deep knee joint and the formation of flat, horizontally directed front and rear feet. On the other hand, there is a poorly developed, short symphysis in the pelvis , which offered relatively few areas of attachment for well-designed leg muscles. In contrast to numerous other mammals , the sacral vertebrae were not fused together. This clearly weak pelvic region with poorly developed hind leg muscles is partly explained by an adaptation to a semi-aquatic way of life, similar to today's hippos , which led to the regression of this entire muscle area. The forelegs, on the other hand, are very mobile, and the front legs, thanks to the special design of the shoulder blade, allow a mobile upward and downward movement of the front part of the body and the pronounced flexibility between the upper and lower arm guarantees a powerful forward thrust in the watery environment. Likewise, the front cervical vertebrae and their muscle marks, which are similar to those of the elephants, show that the head was only limited and mainly movable in lateral directions and was usually carried high. Based on these characteristics, life in tropical forests on the edge of swamps and lakes with mostly soft subsoil is assumed to be likely, a landscape that is also reconstructed for the Fayyum sites on the basis of the accompanying finds. Based on isotope studies on the molars, however, a semi-aquatic way of life has not yet been clearly confirmed. The δ 18 O values ​​turned out to be relatively low and resembled those of today's hippos and other semi-aquatic mammals, but showed hardly any deviating data compared to other fossil mammals from the same sites, so that an amphibious way of life is not separated from a purely terrestrial way of life could. In addition, isotope studies that have also been carried out on the carbon of the molars suggest life in partially open or not completely closed landscapes. Therefore, some researchers assume that Arsinoitherium was adapted to a quadruped country life, but was not a fast runner.

nutrition

Skull of Arsinoitherium , the tilting of the anterior teeth of the lower jaw compared to the posterior ones is clearly recognizable

The structure of the molars is remarkable, the high crowns of which, compared to today's herbivorous mammals , would advocate specialization in hard, silica-rich grass food. Investigations of the arsinoitherium chewing apparatus contradict this approach. The design of the chewing surfaces of the molars with two clearly transverse and protruding enamel ridges ( bilophodont ) in both the upper and lower jaw molars did not allow such plants to be comminuted, as the individual ridges interlocked with one another when the mouth was closed. As a result, only a simple chewing motion was possible, whereby the plant food was merely crushed; Such a tooth design is typical for herbivores specializing in soft leaf or fruit food ( browsing ). The premolars, on the other hand, were able to chop up food better and more extensively due to their simpler chewing surface construction with a single, longitudinally positioned melting bar, which was achieved not only by squeezing but also by grinding. To enable this more complex chewing process, a second articular surface was formed on the lower jaw joint. In addition, when viewed from the side, the premolars in the lower jaw were not in a straight line with the rear molars, but tilted forward at a slight angle, so that the upper and lower tooth strips could not be closed under normal conditions. It was only when the lower jaw was shifted to the second joint surface that the anterior molar dentition was completely closed. It is therefore believed that arsinoitherium was a highly specialized herbivore, preferring soft plant foods. The molars, which are extremely high-crowned for this food source, continue to represent a unique modern feature ( autapomorphy ) of the embryopod within mammals, which is similarly known in the giant sloths , which are also extinct . Otherwise, high-crowned teeth developed largely only in grass-eating herbivores. The nostrils on the front horns, which are relatively far back, suggests a highly flexible upper lip, the muscles of which are also attached to some characteristic openings in the snout area. Such an upper lip is typical of many of today's herbivores that specialize in leaf nutrition.

Function of the horns

The outer surface of the bony horns is criss-crossed by numerous blood channels, which suggests a coating of skin or keratin . It was sometimes assumed that the powerful front horns in particular served as a resonance organ, similar to the bone crests of the hadrosaurs. The function of the horns has not yet been clarified. However, on the basis of these bone formations, a sexual dimorphism can be determined which includes longer horns with pointed ends in males and shorter horns with more rounded ends in females. This may have made them play a role in the mating competition, as is the case with many of today's head-armored mammals, such as rhinos or deer .

Sensory performance

The structure of the cochlea of Arsinoitherium was similar to that of today's elephants, for example due to the two complete turns, which together give a value of 720 °. In the base area there is no evidence of a lamina spiralis secundaria, which is responsible for the perception of certain frequencies . As a result, it can be assumed that the basilar membrane was very expanded, which in turn is an indication of a sensitivity to sounds in the low frequency range . Comparative studies with the inner ear of elephants showed that arsinoitherium may still perceive sound waves around 13.4 Hertz , which is a lower frequency than most mammals today. It is possible that the animals had a sound performance comparable to that of today's elephants, which communicate in infrasound both by means of vocalisation and by means of seismic waves generated by trampling on their feet . The larger pair of horns at Arsinoitherium could have played a role here.

Systematics

Internal structure of the Embrithopoda according to Gheerbrant et al. 2020
 Embrithopoda  

 Stylolophus


   

 Palaeoamasia


   

 Hypsamasia


   

 Crivadiatherium


   

 Namatherium


   

 Arsinoitherium


Template: Klade / Maintenance / 3Template: Klade / Maintenance / 4



Template: Klade / Maintenance / Style

Arsinoitherium is a genus of the Arsinoitheriidae family . The family becomes the order of the extinct embrithopoda found a total of largely unexplored group of mammals of the Paleogene whose exact relationships are not fully understood. Originally the Embrithopoda were placed in the vicinity of today's hyrax , according to a more recent view, the closest living relatives are the manatees and elephants , whereby a possible place in the main group of the sirens as well as the proboscis is possible. All three orders (Proboscidea, Sirenia and Embrithopoda) together form the taxon of Tethytheria . The Embrithopoda can be found for the first time in the early Paleocene around 60 million years ago in western Asia . Whether the Phenacolophidae with Phenacolophus and Minchenella form the parent group of the Embrithopoda is under discussion, but recent studies on the fine structure of tooth enamel rule this out. In the late Oligocene , the Embrithopoda died out again; Overall, due to the paleontological findings, they were spread over large parts of Africa and western Eurasia. Within the Embrithopoda, arsinoitherium is the best-documented and, due to the extremely high-crowned molars and the distinctive body skeleton, the most modern form, until the 1970s it was also the only representative. Today the Embrithopoda are divided into three families, which in addition to the Arsinoitheriidae also include the Stylolophidae and the Palaeoamasidae . The latter two are genetically original lines. The Stylolophidae represents the Stylolophus, which was only described in 2018 . The Palaeoamasidae include, for example, Palaeoamasia and Hypsamasia , whose teeth were less clearly hypsodontic compared to the Arsinoitheriidae. In some cases, the Namatherium , which was only discovered in 2008, is considered to be one of the closest relatives of Arsinoitherium . This was smaller than Arsinoitherium and had not quite as high-crowned molars, it lived in the Middle Eocene and was first detected in Namibia. The exact phylogenetic position of Namatherium is discussed.

Several types of arsinoitherium have been described, two of which are recognized today:

The species A. andrewsi , which was originally also regarded as an independent species , was introduced by Ray Lankester in 1903 , and after a renewed assessment of the finds in 2004, it turned out to be a great representative of A. zitteli , with whom it is now synonymous. Another study from 2008 comes to a similar conclusion and also considers A. giganteum to be problematic, as the genus Arsinoitherium varies greatly, at least in terms of tooth characteristics. The tooth features of Arsinoitherium were also subject to significant changes due to wear, so that an exact separation of different species is difficult. According to this, A. zitteli would be the only recognized species.

The genus and type species Arsinoitherium zitteli from the Fayyum in northern Egypt was scientifically described in 1902 by Hugh John Llewellyn Beadnell . Beadnell named the genus after the Hellenistic-Egyptian Queen Arsinoë II , whose name was the inspiration for the name of the Fayyum Depression in Ptolemaic times. With the specific epithet zitteli , he honored Karl Alfred von Zittel , who in 1873 and 1874 traveled the Libyan desert with the Rohlfs expedition and wrote several important treatises on the geology of the region. The description of the genus and species was based on a skull, but Beadnell also mentioned the hind limbs in his short essay. In the following years, Beadnell's colleague Charles William Andrews published a few more short articles on Arsinoitherium , and he presented a more comprehensive treatment of the genus in 1906 when a catalog was published on the Fayyum fossils. However, arsinoitherium remained largely unknown for a long time, more precise skeletal anatomical and functional morphological analyzes were only carried out in the 1990s.

Arsinoitherium lived largely during the Oligocene . Its distribution area probably extended over the entire African continent and large parts of the Arabian Peninsula. The disappearance of the genus is associated with the formation of a land bridge between Africa and Eurasia 24 million years ago: the mammals that migrated over it displaced the genus along with other Afrotheria.

literature

Arsinoitherium compared to humans
  • Charles W. Andrews: A descriptive catalog of the Tertiary Vertebrata of the Fayum, Egypt. London, 1907, pp. 1-324 (pp. 2-82).
  • Sevket Sen: Dispersal of African mammals in Eurasia during the Cenozoic: Ways and whys. In: Geobios. 46, 2013, pp. 159-172.

Individual evidence

  1. ^ A b Vincent L. Morgan, Spencer G. Lucas: Notes From Diary – Fayum Trip, 1907 (based on the expedition diary and photographs of Walter Granger). In: Bulletin of the New Mexico Museum of Natural History and Science. 22, 2002, pp. 1-148 ( online ).
  2. ↑ a b c d e f g William Sanders, David Tab Rasmussen, John Kappelman: Embrithopoda. In: Lars Werdelin and William Joseph Sanders (eds.): Cenozoic Mammals of Africa. University of California Press, Berkeley, Los Angeles, London, 2010, pp. 115-122.
  3. ↑ a b Mark T. Clementz, Patricia A. Holroyd, Paul L. Koch: Identifying Aquatic Habits Of Herbivorous Mammals Through Stable Isotope Analysis. In: Palaios. 23 (9), 2008, pp. 574-585.
  4. ^ A b c d e f Charles W. Andrews: A descriptive catalog of the Tertiary Vertebrata of the Fayum, Egypt. London, 1906, pp. 1-324 (pp. 2-82).
  5. ^ A b Nicholas Court: The skull of Arsinoitherium (Mammalia, Embrithopoda) and the higher order interrelationships of Ungulates. In: Palaeovertebrata. 22 (1), 1992, pp. 1-43.
  6. ^ A b Lloyd G. Tanner: Embrithopoda. In: Vincent J. Maglio and HBS Cooke (Eds.): Evolution of African Mammals. Harvard University Press, 1978, pp. 278-283.
  7. ↑ a b c d Emmanuel Gheerbrant, Fatima Khaldoune, Arnaud Schmitt, Rodolphe Tabuce: Earliest embrithopod mammals (Afrotheria, Tethytheria) from the early Eocene of Morocco: anatomy, systematics and phylogenetic significance. In: Journal of Mammalian Evolution. , 2020, doi: 10.1007 / s10914-020-09509-6 .
  8. ^ A b Nicholas Court: A unique form of dental bilophodonty and a functional interpretation of peculiarities in the masticatory system of Arsinoitherium (Mammalia, Embrithopoda). In: Historical Biology: An International Journal of Paleobiology. 6 (2), 1992, pp. 91-111.
  9. ^ A b c William J. Sanders, John Kappelman, David Tab Rasmussen: New large-bodied mammals from the late Oligocene site of Chilga, Ethiopia. In: Acta Palaeontologica Polonica. 49 (3), 2004, ISSN  0567-7920 , pp. 365-392.
  10. ↑ a b John Kappelman, David Tab Rasmussen, William J. Sanders, Mulugeta Feseha, Thomas Bown, Peter Copeland, Jeff Crabaugh, John Fleagle, Michelle Glantz, Adam Gordon, Bonnie Jacobs, Murat Maga, Kathleen Muldoon, Aaron Pan, Lydia Pyne , Brian Richmond, Timothy Ryan, Erik R. Seiffert, Sevket Sen, Lawrence Todd, Michael C. Wiemann, Alisa Winkler: Oligocene mammals from Ethiopia and faunal exchange between Afro-Arabia and Eurasia. In: Nature. 426, 2003, pp. 549-552.
  11. ^ A b c Nicholas Court: Morphology and functional anatomy of the postcranial skeleton in Arsinoitherium (Mammalia, Embrithopoda). In: Palaeontographica. Section A 226 (4-6), 1993, pp. 125-169.
  12. ↑ John R. Hutchinson, Cyrille Delmer, Charlotte E. Miller, Thomas Hildebrandt, Andrew A. Pitsillides, Alan Boyde: From Flat Foot to Fat Foot: Structure, Ontogeny, Function, and Evolution of Elephant 'Sixth Toes. In: Science. 334 (6063), 2011, pp. 1699-1703.
  13. ^ A b Announcement of new Mammalian remains from Egypt. In: Nature. 65, 1902, pp. 494-495.
  14. ^ RL: The Fossil Vertebrates of the Fayum. In: Nature. 74, 1906, pp. 175-178.
  15. ^ Henry Fairfield Osborn: The Fayum expedition of the American Museum. In: Science. 25, 1907, pp. 513-516.
  16. ^ A b Donald R. Prothero, Robert M. Schoch: Horns, tusks, and flippers. The evolution of hoofed mammals. Johns Hopkins University Press, Baltimore, 2003, ISBN 0-8018-7135-2 (pp. 141-143).
  17. ↑ Martin Pickford: Première découverte d'une faune mammalienne terrestre paléogène d'Afrique sub-saharienne. In: Comptes Rendus de l'Académie des Sciences de Paris. 302, 1986, pp. 1205-1210 ( [1] ).
  18. ↑ Nicolas Vialle, Gilles Merzeraud, Cyrille Delmer, Monique Feist, Suzanne Jiquel, Laurent Marivaux, Anusha Ramdarshan, Monique Vianey-Liaud, El Mabrouk Essid, Wissem Marzougui, Hayet Khayati Ammar, Rodolphe Tabuce: Discovery of an embrithopoditherium?) in the late Eocene of Tunisia. In: Journal of African Earth Sciences. 87, 2013, pp. 86-92.
  19. ↑ David Tab Rasmussen, Mercedes Gutiérrez: A Mammalian fauna from the Late Oligocene of Northwestern Kenya. In: Palaeontographica Department A. 288 (1-3), 2009, pp. 1-52.
  20. ^ A b c d Abdul Razak Al-Sayigh, Sobhi Nasir, Anne S. Schulp, Nancy J. Stevens: The first described Arsinoitherium from the upper Eocene Aydim Formation of Oman: Biogeographic implications. In: Palaeoworld. 17, 2008, pp. 41-46.
  21. ^ Martin Pickford: Large ungulates from the basal Oligocene of Oman: 1 - Embrithopoda. In: Spanish Journal of Palaeontology. 30 (1), 2015, pp. 33-42.
  22. ↑ John Damuth, Christine M. Janis: On the relationship between hypsodonty and feeding ecology in ungulate mammals, and its utility in Palaeoecology. In: Biological Review. 86, 2011, pp. 733-758.
  23. ^ Dougal Dixon, Barry Cox, RJG Savage, Btrian Gardiner: The Macmillan Illustrated Encyclopedia of Dinosaurs. A Visual Who's Who of Prehistoric Life. Macmillan Publishing, New York NY 1988, ISBN 0-02-580191-0 , p. 237.
  24. ↑ a b Julien Benoit, Samuel Merigeaud, Rodolphe Tabuce: Homoplasy in the ear region of Tethytheria and the systematic position of Embrithopoda (Mammalia, Afrotheria). In: Geobios. 46, 2013, pp. 357-370.
  25. ↑ Erik R Seiffert: A new estimate of afrotherian phylogeny based on simultaneous analysis of genomic, morphological, and fossil evidence. In: BMC Evolutionary Biology. 7, 2007, p. 224. doi : 10.1186 / 1471-2148-7-224
  26. ↑ Rodolphe Tabuce, Laurent Marivaux, Mohammed Adaci, Mustapha Bensalah, Jean-Louis Hartenberger, Mohammed Mahboubi, Fateh Mebrouk, Paul Tafforeau, Jean-Jacques Jaeger: Early Tertiary mammals from North Africa reinforce the molecular Afrotheria clade. In: Proceedings of the Royal Society. Series B 274, 2007, pp. 1159-1166.
  27. ^ A b Sevket Sen: Dispersal of African mammals in Eurasia during the Cenozoic: Ways and whys. In: Geobios. 46, 2013, pp. 159-172.
  28. Jump up ↑ Emmanuel Gheerbrant, Mbarek Amaghzaz, Baadi Bouya, Florent Goussard, Charlène Letenneur: Ocepeia (Middle Paleocene of Morocco): The Oldest Skull of an Afrotherian Mammal. In: PLOSone. 9 (1), 2014, p. E89739, doi: 10.1371 / journal.pone.0089739
  29. ↑ Malcolm McKenna, Earl Manning: Affinities and palaeobiogeographic significance of the Mongolia Palaeogene genus Phenacolophus. Geobios Special 1, 1977, pp. 61-85.
  30. ^ J. David Archibald: Timing and biogeography of the eutherian radiation: fossils and molecules compared. In: Molecular Phylogenetics and Evolution. 28, 2003, pp. 350-359.
  31. ↑ MC Maas, JGM Thewissen, J. Kappelmann: Hypsamasia seni (Mammalia: Embrithopoda) and other Mammals from the Eocene Kartal Formation of Turkey. In: Bulletin of the Carnegie Museum of Natural History. 34, 1998, pp. 286-297.
  32. ↑ Sevket Sen: Eocene Embrithopoda (Mammalia) from Turkey and their paleobiogeographic implications. Thomas Lehmann, Stephan FK Schaal (eds.): The world at the time of Messel. Puzzles in Palaeobiology, Palaeoenvironment and the History of Early Primates. 22nd International Senckenberg Conference Frankfurt am Main, 15th - 19th November 2011, pp. 151–152.
  33. ↑ Martin Pickford, Brigitte Senut, Jorge Morales, Pierre Mein, Israel M. Sánchez: Mammalia from the Lutetian of Namibia. In: Memoir of the Geological Survey of Namibia. 20, 2008, pp. 465-514.
  34. ^ Emmanuel Gheerbrant, Arnaud Schmitt, László Kocsis: Early African Fossils Elucidate the Origin of Embrithopod Mammals. In: Current Biology. 28 (13), 2018, pp. 2167–2173, doi: 10.1016 / j.cub.2018.05.032 .
  35. ↑ Ozan Erdal, Pierre-Olivier Antoine, Sevket Sen: New material of Palaeoamasia kansui (Embrithopoda, Mammalia) from the Eocene of Turkey and a phylogenetic analysis of Embrithopoda at the species level. Palaeontology 59 (5), 2016, pp. 631-655, doi: 10.1111 / pala.12247 .
  36. ↑ Jorge Mondéjar Fernández, Cyrille Delmer, Pascal Tassy: El género Arsinoitherium: catálogo de la colección inédita del Muséum d'Histoire Naturelle de París y the problema del número de especies. In: Palaeontologica Nova. 8, 2008, pp. 291-304.
  37. ^ Hugh John Llewellyn Beadnell: A preliminary note on Arsinoitherium zitteli, Beadn. from the Uppere Eocene strata of Egypt. Egyptian Survey Department, Public Works Ministry, 1902. ( [2] ).
  38. ^ Charles W. Andrews: Further notes on the mammals of the Eocene of Egypt. In: Geological Magazine. 5, 1904, pp. 157-162 ( [3] ).

Web links

Commons : Arsinoitherium  - collection of images, videos and audio files