Macrovertebrate Paleontology and the Pliocene Habitat of Ardipithecus ramidus

International audienceA diverse assemblage of large mammals is spatially and stratigraphically associated with Ardipithecus ramidus at Aramis. The most common species are tragelaphine antelope and colobine monkeys. Analyses of their postcranial remains situate them in a closed habitat. Assessment of dental mesowear, microwear, and stable isotopes from these and a wider range of abundant associated larger mammals indicates that the local habitat at Aramis was predominantly woodland. The Ar. ramidus enamel isotope values indicate a minimal C4 vegetation component in its diet (plants using the C4 photosynthetic pathway), which is consistent with predominantly forest/woodland feeding. Although the Early Pliocene Afar included a range of environments, and the local environment at Aramis and its vicinity ranged from forests to wooded grasslands, the integration of available physical and biological evidence establishes Ar. ramidus as a denizen of the closed habitats along this continuum

Nouvelles observations sur les Lutrinae (Mustelidae : Carnivora, Mammalia) du Miocène terminal–Pliocène basal de l’Aouache moyen, Bassin de l’Afar, Éthiopie

L’article présente de nouvelles données sur les mustélidés du Miocène terminal et du Pliocène basal de la vallée moyenne de l’Aouache (Éthiopie). Cette région permet d’échantillonner les derniers six millions d’années de l’histoire évolutive des vertébrés africains. Les dépôts du Miocène terminal (Membre Asa Koma de la Formation Adu-Asa, 5,54–5,77 Ma) et du Pliocène basal (Membres Kuseralee et Gawto de la Formation Sagantole, 5,2 and 4,85 Ma, respectivement) ont livré de nombreux taxons de grands et petits carnivores parmi lesquels, les mustélidés sont bien représentés. Parmi les genres connus se trouvent le plus ancien Mellivora trouvé en Afrique de l’Est et même en Afrique, une nouvelle espèce de Plesiogulo et une espèce de Vishnuonyx. Cette dernière pourrait correspondre à l’ultime présence du genre en Afrique. Torolutra ougandensis se retrouve sur toute l’étendue des dépôts de l’Aouache moyen. Sivaonyx est représenté par au moins deux espèces, Sivaonyx ekecaman et S. aff. S. soriae. La plupart des mustélidés de l’Aouache moyen sont également connus des sites contemporains d’Afrique de l’Est. Les nouvelles données présentées ici montrent que les mustélidés du Miocène terminal et du Pliocène basal de cette région étaient plus diversifiés qu’on ne l’avait constaté jusque-là.New observations on the Late Miocene and Earliest Pliocene mustelids from the Middle Awash of Ethiopia are presented. The Middle Awash study area samples the last six million years of African vertebrate evolutionary history. Its Latest Miocene (Asa Koma Member of the Adu-Asa Formation, 5.54–5.77 Ma) and Earliest Pliocene (Kuseralee and Gawto Members of the Sagantole Formation, 5.2 and 4.85 Ma, respectively) deposits sample a number of large and small carnivore taxa among which mustelids are numerically abundant. Among the known Late Miocene and Early Pliocene mustelid genera, the Middle Awash Late Miocene documents the earliest Mellivora in eastern Africa and its likely first appearance in Africa, a new species of Plesiogulo, and a species of Vishnuonyx. The latter possibly represents the last appearance of this genus in Africa. Torolutra ougandensis is known from both the Late Miocene and Early Pliocene deposits of the Middle Awash. The genus Sivaonyx is represented by at least two species: S. ekecaman and S. aff. S. soriae . Most of the lutrine genera documented in the Middle Awash Late Miocene/Early Pliocene are also documented in contemporaneous sites of eastern Africa. The new observations presented here show that mustelids were more diverse in the Middle Awash Late Miocene and Early Pliocene than previously documented.</p

Contribution à l’histoire évolutive des chevaux hipparions éthiopiens (Mammalia, Equidae) : morphométrie du squelette postcrânien

Par deux approches différentes, une analyse morphométrique est réalisée sur les troisièmes métapodes et les premières phalanges des « hipparions » provenant des niveaux datés de 6,0 à 3,0 Ma dans le Middle Awash et le Hadar. En utilisant les mesures traditionnelles, des comparaisons morphologiques sont faites par l’intermédiaire : 1) des diagrammes de ratios des mesures transformées en log 10 ; et 2) des variables indépendantes de taille étalonnées pour établir les tendances. Les résultats indiquent que la diversité des « hipparions » était relativement faible pour la période de temps considérée. Une seule lignée dominante, gracile, d’Eurygnathohippus Van Hoepen, 1930, probablement dérivée de l’espèce Eurygnathohippus feibeli (Bernor &amp; Harris, 2003) de Lothagam (Kenya), semble avoir persisté à travers cette période. Cette lignée montre une augmentation de taille avec un changement modéré de la morphologie des métapodes et phalanges. Une forme plus rare et plus robuste, trouvée dans les niveaux éthiopiens datés à 4,0 Ma, est morphométriquement similaire à urygnathohippus turkanense Hooijer &amp; Maglio, 1973 des niveaux datés du Miocène supérieur de Lothagam. Une forme plus petite, au statut systématique incertain, apparaît dans la séquence du Hadar c. 3,0 Ma.A morphometric analysis of third metapodials and first phalanges of Middle Awash and Hadar hipparions dating from the 6.0-3.0 Ma interval was conducted using two methods. Morphological comparisons using standard metrics were made using: 1) log10 ratio diagrams; 2) size independent variables developed with reference to scaling trends for hipparions in general. Results of these analyses suggest that hipparion diversity during this temporal interval was relatively low. A single dominant gracile lineage of Eurygnathohippus Van Hoepen, 1930, most plausibly derived from the Lothagam (Kenya) species Eurygnathohippus feibeli (Bernor &amp; Harris, 2003), would appear to have persisted throughout this interval and is marked by increases in size with measured change in metapodial and phalangeal morphology. A rarer, more robust form is found in the Ethiopian sample at 4.0 Ma and is morphometrically similar to Eurygnathohippus turkanense Hooijer &amp; Maglio, 1973 from late Miocene horizons of Lothagam. Another smaller form, of uncertain systematic status, appears likely late in the Kada Hadar sequence, c. 3.0 Ma.</p

Middle Pliocene Bovidae from Hominid-bearing sites in the Woranso-Mille area, Afar region, Ethiopia

Hominid-bearing sites of the northwestern part of the Woranso-Mille research area, dated to between 3.7 and 3.8 Mya, yield 10 species of Bovidae. The evolutionary stages of the most common species fit quite well this radiometric age. The most abundant bovid is a new species of Aepyceros, of large size, with upright, lyrated horn-cores; it is clearly distinct from the impalas of younger sites in the same area, and from those sampled at Hadar. A new species of Tragelaphus is also common; its horn-cores exhibit reduced anterior keel and antero-posterior compression foreshadowing the most common form at Hadar. A single partial Ugandax skull, despite some primitiveness, may fit into the variation range of U. coryndonae from Hadar. Other tribes are rare; the virtual absence of reduncines is a major difference from younger sites, but the occurrence of a cephalophine and of Neotragus is worth noting. This assemblage unambiguously indicates an environment with a significant component of arboreal vegetation

A new species of Plesiogulo (Mustelidae: Carnivora) from the Late Miocene of Africa

A new species of Plesiogulo (Plesiogulo botori sp. nov.) is described from 5.5–6.0 Ma deposits in East Africa. This new fossil material comes from two localities: Lemudong’o in southern Kenya, and Adu Dora, in the Afar Depression of Ethiopia. The new mustelid species is larger than all known OldWorld Plesiogulo species and extends the temporal and spatial range of the genus inAfrica. Plesiogulo botori sp. nov. documents the earliest occurrence of the genus in Africa in general and the first evidence of its occurrence in late Miocene deposits of eastern Africa. Associated mammalian fauna at both localities where the species has been found indicate a closed/wooded habitat for the genus. This and other occurrences of the genus across Europe, Asia, and the New World indicate that the genus Plesiogulo was geographically widely dispersed during the upper Tertiary.National Science Foundation Leakey Foundation University of Illinois Center for African Studies University of Illinois Research Board Palaeo-anthropology Scientific Trus

A Contribution to the Evolutionary History of Ethiopian Hipparionine Horses (Mammalia, Equidae): Morphometric Evidence From de Postcranial Skeleton

A morphometric analysis of third metapodials and first phalanges of Middle Awash and Hadar hipparions dating from the 6.0-3.0 Ma interval was conducted using two methods. Morphological comparisons using standard metrics were made using: 1) log10 ratio diagrams; 2) size independent variables developed with reference to scaling trends for hipparions in general. Results of these analyses suggest that hipparion diversity during this temporal interval was relatively low. A single dominant gracile lineage of Eurygnathohippus Van Hoepen, 1930, most plausibly derived from the Lothagam (Kenya) species Eurygnathohippus feibeli (Bernor & Harris, 2003), would appear to have persisted throughout this interval and is marked by increases in size with measured change in metapodial and phalangeal morphology. A rarer, more robust form is found in the Ethiopian sample at 4.0 Ma and is morphometrically similar to Eurygnathohippus turkanense Hooijer & Maglio, 1973 from late Miocene horizons of Lothagam. Another smaller form, of uncertain systematic status, appears likely late in the Kada Hadar sequence, c. 3.0 Ma

Fossil birds from the Late Miocene of Chad and Ethiopia and zoogeographical implications

International audienc

A partial distal humerus from the Middle Pleistocene deposits at Bodo, Middle Awash, Ethiopia

The Bodo partial distal humerus with an approximate age of 0.6 million years is one of the very few postcranial remains from the African Middle Pleistocene. Despite its fragmentary status, comparisons of the Bodo humerus with other fossil hominid and modern human samples reveal some insights into African hominids of this time period. The Bodo partial humerus displays distal humeral features very common in the European Middle and Late Pleistocene hominids, such as a relatively wide olecranon fossa and relatively thin lateral and medial pillars adjacent to the fossa. In Africa, the postcranial fossils from the Middle and Late Pleistocene exhibit a surprising amount of morphological diversity. The presence of ‘typically’ Neandertal traits in some, but not all, Homo ergaster, H. Rhodesiensis, and early H. sapiens, together with the greater similarity of some African specimens than others to recent humans, highlights the problem of interpreting the anatomical variation that characterizes African fossil humans. An analysis of frequency–based patterning can help us understand this striking variation. Populations of Middle Pleistocene African hominids, such as the one represented by the Bodo specimen studied here, may have been variable, and their skeletons may have contained a mosaic of modern and non–modern human traits