Cécile Mourer-Chauviré

Les oiseaux fossiles des phosphorites du quercy (éocène supérieur a oligocène supérieur): Implications paléobiogéographiques

Resume Les nouvelles etudes sur les oiseaux des Phosporites du Quercy ont permis de montrer la presence de familles dont la distribution geographique actuelle est differente. Un certain nombre de ces familles peuvent etre considerees comme relictes. La pesence de Phorusrhacidae, auparavant connus au Tertiaire uniquement en Amerique du Sud, apporte un element nouveau concernant le probleme des migrations intercontinentales. On peut envisager pour ce groupe un passage soit par lAfrique, soit par lAmerique du Nord, mais pour le moment il nest pas possible de trancher en faveur de lune ou de lautre hypothese. La faune doiseaux du Quercy montre une tres grande diversite de petits oiseaux percheurs nonpasseriformes. Ces oiseaux devaient occuper des niches ecologiques dont ils ont ensuite ete evinces par les Passeriformes. Beaucoup de ces groupes subsistent a letat de relictes, principalement dans les regions tropicales, et leur histoire paleontologique est encore mal connue.

Première indication de la présence de phorusracidés, famille d'oiseaux géants d'amérique du sud, dans le tertiaire Européen: Ameghinornis nov. gen. (Aves, ralliformes) des phosphorites du quercy, France

Resume Quelques restes doiseaux provenant des Phosphorites du Quercy sont extremement proches des elements correspondants des Phorusrhacides, famille doiseaux disparus et qui comportait des formes geantes, incapables de voler. Ces formes se sont diversifiees en Amerique du Sud, de lOligocene au Pleistocene. Lespece du Quercy represente une forme assez primitive, de taille moyenne et dont laptitude au vol devait etre encore presente, mais probablement reduite. La presence simultanee de Phorusrhacidae en France et en Amerique du Sud a une importante signification biogeographique. Lhypothese la plus vraisemblable pour expliquer cette presence, est de considerer les Phorusrhacidae comme les descendants dun groupe primitif de Ralliformes, deja diversifie dans le continent de Gondwana avant sa separation en differents blocs.

Le bassin lacustre miocène de Bes-Konak (anatolie-turquie): Géologie et introduction a la paléontologie des vertébrés

Resume Le bassin lacustre de Bes-Konak a livre une faune de vertebres conserves a letat dempreintes dans des sediments diatomitiques et volcanosedimentaires. Cette faune est representee par des Poissons Cyprinidae (Leuciscus (P.) etilius Ruckert Ulkumen et une espece nouvelle de Barbus), des Amphibiens Urodeles (adultes de Triturinae) et Anoures (larves de Pelobates sp. et adultes de Rana sp.), dun Chelonien (Chelydridae-Chelydropsis sp.), dun serpent (Colubroide-Colubridae ou Viperidae) et dOiseaux (nouvelle espece de cormoran). Cette faune parait indiquer un âge miocene inferieur ou moyen, ce qui est en accord avec les arguments paleobotaniques, palynologiques et structuraux. Elle confirme egalement les renseignements climatiques deja fournis par les ensembles faunistiques, floristiques et micro-floristiques et par la sedimentation (microclimat sub-tropical au sein dun climat regional tempere chaud). Ces observations completent la connaissance de la nature trophique du lac de Bes-Konak, masse deau ayant tres rapidement evolue vers un etat deutrophie avancee.

MIOCENE SONGBIRDS AND THE COMPOSITION OF THE EUROPEAN PASSERIFORM AVIFAUNA

Abstract Songbirds (Passeriformes) occur in the fossil record of the Northern Hemisphere around the early Oligocene. It has recently been suggested that the major passeriform lineages diverged in Gondwana in the mid- to late Cretaceous and that the oscines, which include all extant European songbirds, originated on the Australian continental plate. Suboscines are assumed to have originated in western Gondwana. Although there is an abundant fossil record of songbirds in Europe, few attempts have been made to set those remains in a phylogenetic context. Our examination of fossil songbirds from three middle Miocene localities in Germany and France shows that many lack the derived morphology of the hypotarsus that characterizes extant Eupasseres (a taxon that comprises oscines and suboscines). We assume that these fossil taxa are outside the crown-group of Eupasseres, which indicates the presence of an ancient songbird avifauna in the Miocene of Europe, in addition to the few fossil Eupasseres already described in the literature.

A Phororhacoid bird from the Eocene of Africa

The bird fossil record is globally scarce in Africa. The early Tertiary evolution of terrestrial birds is virtually unknown in that continent. Here, we report on a femur of a large terrestrial new genus discovered from the early or early middle Eocene (between ∼52 and 46xa0Ma) of south-western Algeria. This femur shows all the morphological features of the Phororhacoidea, the so-called Terror Birds. Most of the phororhacoids were indeed large, or even gigantic, flightless predators or scavengers with no close modern analogs. It is likely that this extinct group originated in South America, where they are known from the late Paleocene to the late Pleistocene (∼59 to 0.01xa0Ma). The presence of a phororhacoid bird in Africa cannot be explained by a vicariant mechanism because these birds first appeared in South America well after the onset of the mid-Cretaceous Gondwana break up (∼100xa0million years old). Here, we propose two hypotheses to account for this occurrence, either an early dispersal of small members of this group, which were still able of a limited flight, or a transoceanic migration of flightless birds from South America to Africa during the Paleocene or earliest Eocene. Paleogeographic reconstructions of the South Atlantic Ocean suggest the existence of several islands of considerable size between South America and Africa during the early Tertiary, which could have helped a transatlantic dispersal of phororhacoids.

Hummingbird with modern feathering: an exceptionally well-preserved Oligocene fossil from southern France.

Hummingbirds (Trochilidae) today have an exclusively New World distribution, but their pre-Pleistocene fossil record comes from Europe only. In this study, we describe an exceptionally preserved fossil hummingbird from the early Oligocene of southeastern France. The specimen is articulated, with a completely preserved beak and feathering. Osteological characters allow to identify it as Eurotrochilus sp. This genus is a stem group representative of Trochilidae and was recently described from the early Oligocene of southern Germany. The new fossil reveals that these European Trochilidae were remarkably modern in size, skeletal proportions and the shape of the wing, tail and beak and hyoid bones. These features confirm the early acquisition of the abilities of hovering and nectarivory in hummingbirds, probably before the Oligocene. In several morphological characteristics, they resemble members of the ‘true hummingbirds’ (subfamily Trochilinae) and differ from hermits (Phaethornithinae). These features, which include a short and square tail and a moderately long, almost straight beak, appear to be primitive within the family Trochilidae.

Montousse 5 (Hautes-Pyrenees), un nouveau remplissage de fissure a faune de vertebres du Pleistocene inferieur

Resume La faune de Montousse 5, qui renferme a ce jour 68 especes, est un ensemble jusquici inconnu en Europe occidentale, et surtout riche en Vertebres de petite et moyenne taille. La microfaune de Mammiferes se correle avec celle dOsztramos 3 (Hongrie), que lon peut dater de la fin du Villafranchien moyen. Elle semble indiquer le passage dune phase froide a une phase chaude, a la fin du Tiglien.

Fossil Anhingas (Aves: Anhingidae) fromEarly Man Sites of Hadar and Omo (Ethiopia) and Olduvai Gorge (Tanzania)

Resume Des restes danhingas ont ete touves dans les gisements a Hominides de lHadar, de lOmo et dOlduvai. Ils correspondent a une nouvelle espece, Anhinga hadarensis, dont lâge se situe entre 3,5 et 1,5 millions dannees. Cette espece est probablement lancetre immediat de la forme africaine actuelle, Anhinga rufa, mais presente egalement des caracteres communs avec la forme americaine actuelle, A. anhinga.

New Specimens of Lithoptila Abdounensis (Aves, Prophaethontidae) from the Lower Paleogene of Morocco

Abstract New specimens of Lithoptila abdounensis (Prophaethontidae) including long bones and fragments of mandibulae are described from the Upper Paleocene and Lower Eocene of the Ouled Abdoun Basin, Morocco. Elongated and slender wing bones suggest that this bird was an offshore or pelagic feeder capable of efficient flight. Lithoptila approximates Prophaethon in size but differs from the latter taxon in various features of the mandibula, coracoideum and femur. The anatomy and size of Lithoptila closely match those of Zhylgaia aestiflua, a putative shorebird (Charadriiformes) from the Upper Paleocene of Kazakhstan, known from two partial humeri. Consequently, we assign Zhylgaia aestiflua to the Prophaethontidae. The three species of Prophaethontidae inhabited tropical seas and most likely had comparable ecological niches.

Out of Africa: Fossils shed light on the origin of the hoatzin, an iconic Neotropic bird.

We describe the earliest fossils of the enigmatic avian taxon Opisthocomiformes (hoatzins) from the Oligo-Miocene (22–24xa0mya) of Brazil. The bones, a humerus, scapula and coracoid, closely resemble those of the extant hoatzin, Opisthocomus hoazin. The very similar osteology of the pectoral girdle in the new Brazilian fossil compared to the extant O. hoazin, in which it reflects peculiar feeding adaptations, may indicate that hoatzins had already evolved their highly specialized feeding behavior by the mid-Cenozoic. We further show that Namibiavis senutae from the early Miocene of Namibia is another, previously misclassified representative of Opisthocomiformes, which documents that the extant Neotropic distribution of hoatzins is relictual. Because of the weak flight capabilities of hoatzins, their occurrence on both sides of the South Atlantic is of particular biogeographic interest. We detail that this distribution pattern is best explained by dispersal from Africa to South America, and that Opisthocomiformes provide the first example of transatlantic rafting among birds.