Saloumia
| Saloumia | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Middle Eocene | ||||||||||||
| 47.8 to 41.3 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Saloumia | ||||||||||||
| Tabuce , Sarr , Adnet , Lebrun , Lihoreau , Martin , Sambou , Thiam & Hautier , 2019 | ||||||||||||
Saloumia is an extinct genus from the order of the proboscis . It is one of the original representatives of this group of mammals and livedin western Africa in the Middle Eocene around 44 million years ago. So far there is only one single tooth from Senegal . Due to the pronounced bumpy chewing surface, Saloumia is probably in a closer relationship to Moeritherium . The genus was scientifically introduced in 2019, but the associated find came to light in the 1950s.
description
The only known find of Saloumia to date includes a right upper molar 10.7 mm long and 12.3 mm wide, but the posterior part is missing. The dimensions of the tooth mediate between the smaller Eritherium and Phosphatherium and the larger Moeritherium . The tooth was low-crowned ( brachyodont ), more clearly than in Moeritherium . The chewing surface was characterized by four humps (Paraconus and Metaconus on the cheek side, Protoconus and Hypoconus on the tongue side). The tips of these had obviously broken off before the fossilization . The four cusps each formed two pairs, which were arranged perpendicular to the longitudinal axis of the teeth. The tooth was built bilophodontically , which corresponds to the very early proboscis. The front pair of cusps (Paraconus and Protoconus) had no additional ridges or ridges, so that one can speak of a bunodontic tooth structure. The bases of the two humps were, however, connected to one another, and a small minor hump rose with the paraconule. The rear pair of cusps (metaconus and hypoconus) is damaged, but the hypoconus was originally relatively central and very large, its dimensions corresponded to those of the protoconus. Its inwardly shifted position differs from its more marginal position at Moeritherium . There was no metaconule on the second pair of cusps. The central longitudinal groove that divides the tooth, including the two pairs of cusps, into two halves, was only weakly formed. A well-developed cingulum, a low enamel bulge, encircled the molar from the paraconus over the front edge to the tooth flank on the tongue side. Saloumia shares the tongue-side position of the cingulum as a special feature with Moeritherium . Both on the tongue side and on the cheek side of the tooth, the cingulum merged into a shear edge (entostyl and ectostyl). The enamel as a whole was thick and heavily furrowed.
Fossil finds
There is currently only one single tooth from Saloumia . This was brought to light from the Lam-Lam formation near the village of M'Bodione Dadere north of the city of Kaolack in the central-western part of Senegal . The landscape in the region is relatively flat and is traversed by the Saloum river, the overlying layers form several meters thick Quaternary sands. Access to fossil outcrops is usually only guaranteed by wells and boreholes. The Lam-Lam formation consists of a limestone rich in mollusks and sea urchins ( Schillkalkstein ), which alternates with clay limestone and marls . The limestones contain various foraminifera , of which Globigerinatheka , Cassigerinelloita and Pseudohastigerina are typical of the Lutetium , which corresponds to the Middle Eocene . The tooth find should therefore be around 44 million years old. Other vertebrates from the Lam-Lam formation can be assigned to the ray fins . The overlying late Middle Eocene Taïba Formation also contained the remains of an ancient whale, which is probably close to the Basilosauridae .
Systematics
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Abbreviated internal systematics of the early proboscis according to Tabuce et al. 2019
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Saloumia is an extinct species from the order of the trunk animals (Proboscidea). Due to its bilophodontic molar tooth, it is one of the earliest representatives of this order, some of which are included in the group of the Plesielephantiformes . This also includes forms such as Eritherium , Phosphatherium , Numidotherium , Moeritherium , Daouitherium and others, together with these early forms Saloumia forms one of the most complete sequences from the early history of a mammal order to date. Another common characteristic of the Plesielephantiformes is the horizontal change of teeth in contrast to later proboscis. From a systematic point of view, Saloumia has not yet been assigned to any particular family within the proboscis . The bunodonte , that is, the bumpy chewing surface pattern of the tooth, connects the genus more closely with Moeritherium than with the other early forms such as Phosphatherium , Numidotherium or Barytherium , which are characterized by stronger ridges between the cusps, i.e. lophodontic teeth. Further similarities with Moeritherium can be found in the angled tooth enamel and the cingulum formed on the tongue side. Perhaps Saloumia is at the base of the development of moeritheriider trunk animals.
The first scientific description of Saloumia was made in 2019 by Rodolphe Tabuce and research colleagues based on the tooth find from the Lam-Lam formation in central-western Senegal . The generic name is derived from the Saloum river , which flows through the flat, undulating landscape of the type region. The species S. gorodiskii was established together with the genus . The specific epithet honors the geologist Alexandre Gorodiski , who discovered the tooth in 1952 during mapping work in the region around M'Bodione Dadere in a 20 m deep well. Gorodiski published the find a year later together with René Lavocat . They referred him to Moeritherium , but noted that the significantly stronger bunodontic character of the molar compared to Moeritherium might justify an independent genus status.
literature
- Rodolphe Tabuce, Raphaël Sarr, Sylvain Adnet, Renaud Lebrun, Fabrice Lihoreau, Jeremy E. Martin, Bernard Sambou, Mustapha Thiam and Lionel Hautier: Filling a gap in the proboscidean fossil record: a new genus from the Lutetian of Senegal. Journal of Paleontology, 2019, doi: 10.1017 / jpa.2019.98
Individual evidence
- ↑ a b c d e Rodolphe Tabuce, Raphaël Sarr, Sylvain Adnet, Renaud Lebrun, Fabrice Lihoreau, Jeremy E. Martin, Bernard Sambou, Mustapha Thiam and Lionel Hautier: Filling a gap in the proboscidean fossil record: a new genus from the Lutetian of Senegal. Journal of Paleontology, 2019, doi: 10.1017 / jpa.2019.98
- ↑ Maureen A. O'Leary, Raphaël Sarr, Raymond Malou, El Hdji Sow, Christopher J. Lepre and Robert V. Hill: A New Fossil Amiid from the Eocene of Senegal and the Persistence of Extinct Marine Amiids after the Cretaceous – Paleogene Boundary . Copeia 4, 2012, pp. 603-608
- ↑ Phillip D. Gingerich: Cetacea. In: Lars Werdelin and William Joseph Sanders (eds.): Cenozoic Mammals of Africa. University of California Press, Berkeley, London, New York, 2010, pp. 873-899
- ↑ Jehezekel Shoshani, WJ Sanders and Pascal Tassy: Elephants and other Proboscideans: a summary of recent findings and new taxonomic suggestions. In: G. Cavarretta et al. (Ed.): The World of Elephants - International Congress. Consiglio Nazionale delle Ricerche. Rome, 2001, pp. 676-679
- ↑ Jehezekel Shoshani and Pascal Tassy: Advances in proboscidean taxonomy and classification, anatomy & physiology, and ecology and behavior. Quaternary International 126-128, 2005, pp. 5-20
- ↑ Emmanuel Gheerbrant: Paleocene emergence of elephant relatives and the rapid radiation of African ungulates. PNAS 106 (6), 2009, pp. 10717-10721.
- ↑ Emmanuel Gheerbrant, Baadi Bouya and Mbarek Amaghzaz: Dental and cranial anatomy of Eritherium azzouzorum from the Paleocene of Marocco, earliest known proboscidean material. Palaeontographica, Department A 297 (5/6), 2012, pp. 151-183.