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Phosphatherium escuilliei, from the Thancetian of the Ouled Abdoun basin , oldest known Proboscidean from Africa


, : Phosphatherium escuilliei, from the Thancetian of the Ouled Abdoun basin , oldest known Proboscidean from Africa. Geobios (Lyon) 31(2): 247-269

We detail here the study of Phosphatherium escuilliei from the Paleocene of the Ouled Abdoun Basin, Morocco. This fossil is both the oldest proboscidean and the oldest modern ungulate. The species, known by two specimens, is dated as Thanetian on the basis of the foraminifera and the selachians identified in the matrix. P. escuilliei shows several derived proboscidean features, especially the true lophodont pattern of the molars, but also remarkable primitive features such as a vestigial dilambdodonty and a very small size, the smallest reported in the order. The vestigial dilambdodonty is interpreted here as a reminiscence of the pantomesaxonian supergroup. Primitive tethythere features are also noticed, especially the orbit in anterior position and the occurrence of a postentoconule. Numidotherium koholense from El Kohol (late Early Eocene of Algeria) is the most closely related proboscidean to P. escuilliei, and the two species are included in the same family Numidotheriidae. However, the available material shows only one possible synapomorphy: the absence of lingual cingulum in the upper molars. P. escuilliei is the most primitive known lophodont proboscidean. The dP4/ of P. escuilliei strongly recalls the single known tooth of the enigmatic species Khamsaconus bulbosus from the Ypresian site of N'Tagourt 2, Morocco. Shared features such as the occurrence of a postentoconule and the incipient bilophodonty indicate affinities of K. bulbosus with tethytheres, and others such as the absence of conules are even possibly suggestive of affinities with lophodont proboscideans. The K. bulbosus morphology remains however clearly more primitive than that of P. escuilliei, especially in being more bunodont. Phosphatherium, Numidotherium, Barytherium and even Khamsaconus raise the problem of a lophodont ancestral proboscidean morphotype, which is in accordance with the recent hypothesis of Court (1995) regarding Moeritherium as more derived than Numidotherium. P. escuilliei supports an early age of the radiation of modern orders of mammals, which was earlier than the late Paleocene, as well as its "explosive" pattern if it is closely connected to the extinctions of the K/T boundary. It shows also, more clearly than the taxa from the Adrar Mgorn fauna (late Paleocene of Morocco), the old age of the eutherian presence in the Arabo-African domain. It also supports the African origin of true proboscideans.

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Related references

Gheerbrant, E.; Sudre, J.; Cappetta, H.; Bignot, G., 1998: Phosphatherium escuilliei, from the Thancetian of the Ouled Abdoun basin (Morocco), oldest known Proboscidean (Mammalia) from Africa. We detail here the study of Phosphatherium escuilliei from the Paleocene of the Ouled Abdoun Basin, Morocco. This fossil is both the oldest proboscidean and the oldest modern ungulate. The species, known by two specimens, is dated as Thanetian on...

Gheerbrant, E..; Sudre, J..; Cappetta, H..; Bignot, G.., 1998: Phosphatherium escuilliei from the Thanetian of the Ouled Abdoun basin Morocco, oldest known proboscidean Mammalia from Africa Phosphatherium escuilliei du Thanetien du Bassin des Ouled Abdoun Maroc, plus ancien proboscidien Mammalia dAfrique. Geobios (Villeurbanne): 312: 247-269

Gheerbrant E.; Sudre J.; Cappetta H.; Bignot G., 1998: Phosphatherium escuilliei, from the Thanetian of the Ouled Abdoun Basin (Morocco), oldest known Proboscidean (Mammalia) from Africa. We detail here the study of Phosphatherium escuilliei from the Paleocene of the Ouled Abdoun Basin, Morocco. This fossil is both the oldest proboscidean and the oldest modern ungulate. The species, known by two specimens, is dated as Thanetian on...

Anonymous, 1998: Phosphatherium escuilliei du Thanetien du Bassin des Ouled Abdoun (Maroc), plus ancien proboscidien (Mammalia) d'Afrique

Gheerbrant, E.; Sudre, J.; Cappetta, H.; Mourer-Chauvire, C.; Bourdon, E.; Iarochene, M.; Amaghzaz, M.; Bouya, B., 2003: The mammal localities of Grand Daoui Quarries, Ouled Abdoun Basin, Morocco, Ypresian a first survey Les localites a mammiferes des carrieres de Grand Daoui, bassin des Ouled Abdoun, Maroc, Ypresien premier etat des leux. Bulletin de la Societe Geologique de France, 1743: 279-293

Gheerbrant, E.; Sudre, J.; Tassy, P.; Amaghzaz, M.; Bouya, B.; Iarochene, M., 2005: New data on Phosphatherium escuilliei Mammalia, Proboscidea from the early Eocene of Morocco, and its impact on the phylogeny of Proboscidea and lophodont ungulates Nouvelles donnees sur Phosphatherium escuilliei Mammalia, Proboscidea de IEocene inferieur du Maroc, apports a la phylogenie des Proboscidea et des ongules lophodontes. We report here significant new material belonging to the oldest and most primitive known Proboscidean, Phosphatherium escuillei Gheerbrant, Sudre & Cappetta, 1996, from the early Eocene of the Ouled Abdoun phosphatic basin, Morocco. This material...

Mendiola, C., 1999: New Myliobatoidea Neoselachii, Batomorphii of the Thanetian ? period from Oued Zem Ouled Abdoun Basin, Morocco Myliobatoideos nuevos Neoselachii, Batomorphii del Thanetiense ? de Oued Zem Cuenca de los Ouled Abdoun, Marruecos. Revista de la Societat Paleontologica d'Elx Seccion Paleontologica. Diciembre; 6: 1-42

Cavin, L..; Bardet, N..; Cappetta, H..; Gheerbrant, E..; Iarochene, S.M.hamed.; Sudre, J.., 2000: A new Palaeocene albulid Teleostei Elopomorpha from the Ouled Abdoun phosphatic basin, Morocco. Geological Magazine. September; 1375: 583-591

Hirayama, R.; Tong, H., 2003: Osteopygis (Testudines: Cheloniidae) from the Lower Tertiary of the Ouled Abdoun phosphate basin, Morocco. Osteopygis emarginatus Cope 1868 is described from the Lower Tertiary of the Ouled Abdoun phosphate basin, Morocco, on the basis of skulls and lower jaws. Osteopygis is a cosmopolitan turtle that had a wide geographical distribution during the Lat...

Moutaouakil Driss; Giresse P., 1993: Petrology and sedimentary environments of Meso-Cenozoic phosphates from the Ouled Abdoun Basin, Morocco. Bulletin de la Societe Geologique de France, Huitieme Serie 164(3): 473-491