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Paleocene emergence of elephant relatives and the rapid radiation of African ungulates - PubMed

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Paleocene emergence of elephant relatives and the rapid radiation of African ungulates

Emmanuel Gheerbrant. Proc Natl Acad Sci U S A. 2009.

Abstract

Elephants are the only living representatives of the Proboscidea, a formerly diverse mammalian order whose history began with the 55-million years (mys) old Phosphatherium. Reported here is the discovery from the early late Paleocene of Morocco, ca. 60 mys, of the oldest and most primitive elephant relative, Eritherium azzouzorum n.g., n.sp., which is one of the earliest known representatives of modern placental orders. This well supported stem proboscidean is extraordinarily primitive and condylarth-like. It provides the first dental evidence of a resemblance between the proboscideans and African ungulates (paenungulates) on the one hand and the louisinines and early macroscelideans on the other. Eritherium illustrates the origin of the elephant order at a previously unknown primitive stage among paenungulates and "ungulates." The primitive morphology of Eritherium suggests a recent and rapid paenungulate radiation after the Cretaceous-Tertiary boundary, probably favoured by early endemic African paleoecosystems. At a broader scale, Eritherium provides a new old calibration point of the placental tree and supports an explosive placental radiation. The Ouled Abdoun basin, which yields the oldest known African placentals, is a key locality for elucidating phylogeny and early evolution of paenungulates and other related endemic African lineages.

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Conflict of interest statement

The author declares no conflict of interest.

Figures

Fig. 1.
Fig. 1.

Skull and upper dentition of Eritherium azzouzorum n.g., n.sp. (A–G) Holotype, MNHN PM69. (A and B) Anterior part of skull (rostrum) with maxilla and jugals in mesial and ventral views and showing nasal cavity, zygomatic arches and jugal dentition. (C) Left P3–4, M1–3, occlusal sketch. (D and E) Frontals and nasals in dorsal view, specimen MHNT PAL 2006.0.18–20 (Museum National d'Histoire Naturelle de Toulouse). (F and G) Frontal and rostrum (jugal and right maxillary with P3–4, M1–3) in lateral view (G is reversed for reconstruction). (H and I) Right P3–4, M1–3 in occlusal view (H is SEM view of I). (Scale bar, 10 mm.)

Fig. 2.
Fig. 2.

Lower dentition of Eritherium azzouzorum n.g., n.sp. (A) Reconstruction of lower tooth row: M3–1, P4–1 and alveoli for C1, I3–1 in occlusal view, based on specimens OCP DEK/GE 307 (M3–1), MNHN PM28 (P4–2, alveoli of C1, I3–1), PM84 [(d)P1]. (B) Sketch of enlarged and styliform I2 in occlusal (dorsal) and lingual views, plus alveoli of (d)P1, C1 and I3 from specimen MNHN PM50. (C and D) Left M3–1, specimen OCP DEK/GE 307, in occlusal view (drawing and SEM photograph). (Scale bar, 10 mm.)

Fig. 3.
Fig. 3.

Relationships of Eritherium azzouzorum n.g., n.sp. Cladograms resulting from parsimony analysis with TNT program (11) based on modified matrix for Phosphatherium analysis (7) (see

SI Appendix

). With respect to Phosphatherium analysis (7), several basal taxa are added to test basal relationships of Paenungulata, and Khamsaconus, which TNT “pruned tree” procedure (11) identifies as the most unstable taxon, is excluded from the analysis. (A) Consensus of 14 most parsimonious trees (L = 455 steps, CI = 58.7; CI = 41.8) resulting from exact analysis (nelsen); upper numbers in nodes refer to Bremer indices, lowers refer to bootstrap indices. (B) Standard TNT “implied weighting” analysis (L = 457 steps, RI = 58.4; CI = 41.6) with congruent topology to that resulting from Phosphatherium study (7), in particular with similar primitive position of Anthracobunia and Embrithopoda within Tethytheria. In both cases the proboscidean (basal) relationship of Eritherium azzouzorum n.g., n.sp is well supported.

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References

    1. Gheerbrant E, Tassy P. Origin and evolution of proboscideans (Translated from French) C R Palevol. 2009;8:281–294.
    1. Gheerbrant E, Sudre J, Cappetta H. A Palaeocene proboscidean from Morocco. Nature. 1996;383:68–71.
    1. Novacek MJ. Mammalian phylogeny: Shaking the tree. Nature. 1992;356:121–125. - PubMed
    1. Wible JR, Rougier GW, Asher RJ. Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary. Nature. 2007;447:1003–1006. - PubMed
    1. Gheerbrant E, Sudre J, Cappetta H, Bignot G. Phosphatherium escuilliei, from the Thanetian of the Ouled Abdoun basin (Morocco), oldest known Proboscidean (Mammalia) from Africa (Translated from French) Geobios. 1998;30:247–269.

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