Bothriogenys

Bothriogenys
Two specimens of Bothriogenys can be found in a shallow river, with an arsinoitherium in the background
Temporal occurrence
Upper Eocene to Upper Oligocene
Locations
Egypt , Ethiopia , Thailand , People's Republic of China
Systematics
Laurasiatheria Artiodactyla (Artiodactyla) Hippopotamoidea Anthracotheriidae Bothriodontinae Bothriogenys
Scientific name
Bothriogenys
Schmidt , 1913

Bothriogenys is an extinct genus of mammals from the Eocene and Oligocene of Africa and Asia. She ate exclusively herbivore .

features

Bothriogenys was smaller than related species like Anthracotherium . The snout was greatly elongated, resulting in diastemas between the teeth of the premolar rows. Bothriogenys can mainly be distinguished from other genera on the basis of the teeth. The incisors were not enlarged, but, like today's hippos, grew back throughout their life. The canines remained small, there was also no significant sexual dimorphism as in other species of the Anthracotheriidae, in which the canines of the males grew into tusks . The upper molars ended in five cusps.

Way of life

It is believed that Bothriogenys lived semiaquatically like today's hippos. Bothriogenys fossils were always found in deposits in river beds. The Moeritherium , a proboscis from the Eocene to the Oligocene, was also found at the same sites . A similar way of life as a semi-aquatic herbivore is ascribed to this.

Investigations of the relationships between the stable oxygen isotope O ¹⁸ and O ¹⁶ in tooth enamel provide clues as to whether they were a primarily terrestrial or semi-aquatic live animal. The ratio of the stable carbon isotopes C ¹³ and C ¹² makes it possible to reconstruct the composition of the plant food, since this ratio is higher in C4 plants than in C3 plants . The low O ¹⁸ / O ¹⁶ ratio in tooth enamel suggests, according to comparative studies on fossil and recent animals, that Bothriogenys was predominantly aquatic. Meanwhile, the low C ¹³ / C ¹² ratio suggests that Bothriogenys may have ate more aquatic plants than most other herbivorous mammals. These findings contradict many theses that ascribed a way of life similar to today's pigs to the early representatives of the Anthracotheriidae family . Unlike today's hippos, who consume most of their food on land at night, Bothriogenys may have spent most of its life in the water and found food there.

Research history

Fossils of various mammals were collected at the beginning of the 20th century by Richard Margrave in the Gebel-Qatrani formation in Fayyum in northern Egypt for the collection of natural objects in Stuttgart. The rich material also contained bones from three species of primates , various rodents and insectivores, and fossil bats. There were also skull bones of three differently sized species among them, which had been assigned to the Anthracotheriidae of the genus Ancodon . Numerous existing foot bones also matched the skull bones. The conservator of the geological, palaeontological and mineralogical department of the natural history collection, Eberhard Fraas , gave these fossils to the paleontologist Martin Schmidt from Aschersleben for description. In 1913 Schmidt did not place these Egyptian Anthracotheriidae in the Ancodon , but in the genus Brachyodus , which Depéret had established in 1895. Schmidt established his own sub-genus for the new species Brachyodus fraasi and Brachyodus rugulosus , which he called Bothriogenys . This subgenus was later elevated to a genus and the third species described by Schmidt in 1913, originally called Brachyodus andrewsi , was placed in this new genus as Bothriogenys andrewsi .

Systematics

Bothriogenys was an even-toed ungulate and is in a clade (Ruminantiomorpha) with today's ruminants . There are currently five known species that lived from the late Eocene to the late Oligocene . The type species Bothriogenys fraasi died out in the lower Oligocene. Like most other species, it lived in today's Egypt as far as Ethiopia and is known from finds from the Fayyum . Bothriogenys orientalis was discovered in Thailand, and finds from southern China can also be assigned to the genus Bothriogenys . It is believed that the North African species descended from the Asiatic ones. That assumes a land connection between the Asian and the African continent at least in the late Eocene. Later this land bridge was interrupted and formed anew in the Miocene.

• Bothriogenys fraasi Schmidt, 1913
• Bothriogenys andrewsi Schmidt, 1913
• Bothriogenys rugulosus Schmidt, 1913
• Bothriogenys gorringei (Andrews & Bradnell, 1902)
• Bothriogenys orientalis Ducrocq, 1997 (Thailand)

Afromeryx africanus , previously called Bothriogenys africanus (Andrews, 1899), was described as early as the 19th century and also comes from Egypt. However, it was found in layers of the Lower Miocene , making it younger than any other species of Bothriogenys . In 1991, Bothriogenys africanus was placed in the genus Afromeryx by Pickford .

Qatraniodon parvus (Andrews, 1906), of which only a part of the lower jaw from the Oligocene in Egypt has been found for a long time, was known for a long time as Bothriogenys parvus , but was placed in its own genus by Ducrocq in 1997 because of its slimmer molars . The genus is named after the place where it was found at Jebel Qatrani in Egypt.

Finds from the Lokichar Basin southwest of the Turkana Basin in East Africa were initially associated with Bothriogenys . The researchers found numerous upper and lower jaws that are similar in size and shape to those of Bothriogenys gorringei from the Fayyum. The five-humped upper molars typical of Bothriogenys were found. The molars of the lower jaw are much more massive than those of the previously known Bothriogenys species. In 2015 they were described as belonging to the genus Epirigenys , which is closely related to Bothriogenys .

Individual evidence

1. ^ ^{A b c} Donald R. Prothero, Scott E. Foss (Ed.): The Evolution of Artiodactyls. Johns Hopkins University Press, Baltimore MD 2007, p. 95 ISBN 978-0-8018-8735-2
2. ↑ ^{a b} Mark T. Clementz, Patricia A. Holroyd, Paul L. Koch: Identifying Aquatic Habits Of Herbivorous Mammals Through Stable Isotope Analysis. Palaios, 23, 9, pp. 274–285, 2008. (Accessed online January 31, 2013)
3. ↑ Martin Schmidt: About the even-toed ungulate of the fluviomarinen layers of the Fajum; odontographic and osteological material. Geological and paleontological treatises. NF Vol. XI, Verlag Gustav Fischer, Jena 1913
4. ^ M. Spaulding, MA O'Leary, J. Gatesy: Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alter Interpretations of Key Fossils and Character Evolution. PLoS ONE 4, 9, e7062, 2009 doi : 10.1371 / journal.pone.0007062 Online (English)
5. ^ Meave Leaky, Ari Grossman, Mercedes Gutiérrez, John G. Fleagle : Faunal Change in the Turkana Basin during the Late Oligocene and Miocene. Evolutionary Anthropology: Issues, News, and Reviews, Special Issue: The Turkana Basin, 20, 6, pp. 238-253, 2011 doi : 10.1002 / evan.20338
6. ^ Fabrice Lihoreau, Jean-Renaud Boisserie, Fredrick Kyalo Manthi and Stéphane Ducrocq: Hippos stem from the longest sequence of terrestrial cetartiodactyl evolution in Africa. Nature Communications 6, 2015 doi : 10.1038 / ncomms7264

literature

• Donald R. Prothero, Scott E. Foss (Eds.): The Evolution of Artiodactyls. Johns Hopkins University Press, Baltimore MD 2007, p. 95 ISBN 978-0-8018-8735-2
• J.-R. Boisserie, F. Lihoreau, M. Orliac, RE Fisher, EM Weston, S. Ducrocq. Morphology and phylogenetic relationships of the earliest known hippopotamids (Cetartiodactyla, Hippopotamidae, Kenyapotaminae). Zoological Journal of the Linnean Society, 158, pp. 325-266, 2010
• Martin Schmidt: About artifacts of the fluviomarinen layers of the Fajum; odontographic and osteological material. Geological and paleontological treatises. NF Vol. XI, Verlag Gustav Fischer, Jena 1913 (first description of three Bothriogenys species from the holdings of the Natural History Collection in Stuttgart)