Showing papers in "Annales De Paleontologie in 2000"

The phylogenetic position of Isalorhynchus genovefae, a Late Triassic rhynchosaur from Madagascar

Abstract: New specimens of the rhynchosaur Zsalorhynchus genovefae Buffetaut, 1983, have been found in the Makay Formation (Late Triassic of the Morondava Basin), Malio River area, southwest Madagascar. The material includes several maxillae as well as the first known rhynchosaur dentaries from the region. The maxilla bears a single longitudinal groove, with fewer than three longitudinal tooth rows both medial and lateral to it. The dentary possesses a single blade, with an additional row of teeth on its lingual surface. A phylagenetic study, based on the morphological features possible to measure for Zsalorhynchus, as well as on previous cladistic analysis of Rhynchosauria, showed that the Malagasian rhynchosaur is nested within the genus Hyperodapedon, and a new combination - H. genovefae - is proposed. The phyloge- netic study also depicts clear trends in the tooth evolution of Late Triassic rhynchosaurs, with the reduction of the medial structures in relation to the lateral ones, in both maxilla and dentaty. 0 2000 Editions scientitiques et medicales Elsevier SAS

Crocodiles from the Beglia Formation, Middle/Late Miocene boundary, tunisia, and their significance for saharan palaeoclimatology

Abstract: Previous studies have mentioned the presence of crocodiles in the Beglia Formation of Tunisia, but few detailed descriptions of the remains have been published. This paper reports on fossils attributed to Crocodylus lloydi and Euthecodon sp. and their presence in Tunisian Late Miocene fluviatile deposits indicates that the Sahara was extremely humid as recently as 10 Ma.

Remains of a Pliocene Mammut borsoni (Hays, 1834) (Proboscidea, Mammalia), from Milia (Grevena, W. Macedonia, Greece)

Abstract: A partial skeleton of the mastodont Mammut borsoni (Hays, 1834) (Proboscidea), was excavated from Pliocene deposits at Milia — Grevena, W. Macedonia, in 1996–1999. The skeleton includes substantial portions of the skull — maxillary area — with left and right molar series (M 2 + M 3 ); with the longest upper tusks ever found in Greece (4.39 m); the most complete mandible with left and right molar series (M 2 + M 3 ) and two lower incisor tusks, as well as post-cranial skeleton. It represents a very large adult of about 40 years in age. The high age of the finding is partly corroborated by ESR dating studies of tooth enamel, indicating an age probably beyond the upper dating range of this technique (approx. 800 000 years). The evolutionary position of this specimen among mammutids is also discussed.

Pterosaurs from the Lower Cretaceous (?Berriasian) of Anoual, Morocco

Abstract: A report on the pterosaurian remains from the Lower Cretaceous of Anoual, Morocco, is presented. The material consists of teeth possibly documenting two groups. One of them cannot be clearly established but might be ornithocheirid, while the most numerous teeth are reminiscent of those of gnathosaurine. This possible attribution might be consistent with a Berriasian age for the calcareous lens containing the microvertebrate assemblages of Anoual.

Distribution and palaeoecology of non marine algae and stromatolites: II, the limagne of allier Oligo-Miocene lake (central France)

Abstract: The lacustrine, Oligo-Miocene deposits of the Limagne d'Allier (central France) contain a wide range of stromatolitic builtups: oolites, spherulites, ostracod encrusted shells, oncolites, and unmovable builtups (floors, balls, columns) being from some cm3 to several m3 in volume. These builtups are contained in quartzo-feldspathic sands, bioclastic sands, micritic muds, marls with root traces. All the sediments are calcitic; dolomite, in the form of isolated rhombs, is excessively rare. From a palaeoalgological point of view, we recognize 11 morphospecies belonging to 7 morphogenus, associated with thin layers of micrite supposed to be bacterial in origin. The algal encrustations were initially entirely micritic; in two species (Broutinella arvernensis and B. ramulosa) a more or less strong recrystallization in sparite of radial palissadic type occurs. Each species can construct a monospecific layer (lamination), but often a single lamination contains two species, and a single builtup exhibits several species. The small, movable builtups (oolites, spherulites, encrusted ostracod shells) present all the microscopical aspects of the laminations of Broutinella arvernensis. They are interpreted as resulting from biological activity, and not from a purely physico-chimical precipitation. The oncolites and the unmovable builtups are of a great internal complexity. We can schematically distinguish: the filament masses of Cladophorites incrustata, with individual filaments encrusted by Broutinella arvernensis and/or ‘bacterial’ micrite, and with a peripheral encrustation of the masses of filaments; the homogeneous stromatolites, proceeding from the growth of algal biocoenosis making floors, hemispheres and small columns, the shape of which is only linked with the algal development; the heterogeneous stromatolites, whose the initial shape is that of the encrusted substrate (accumulation of larval tubes of phrygans assembled on a vegetal tuft before hatching). On the microscopic scale, we can oppose the monobiocoenotic stromatolites, made of identical doublets (= couplets, one light lamination plus one dark lamination), and the polybiocoenotic stromatolites, made up of the superimposition of sets of doublets resulting from the activity of different biocoenosis. From a palaeoecological point of view, the climatic oscillations recognized during the epoch (warmer/cooler, drier/more humid) do not seem to have influenced the growth of the algae nor the shape or distribution of the builtups. The faunas of the associated sediments are rich in individuals and poor in species (larvae of phrygans, Cypris, hydrobiids; aerial helicids), which indicates a low salinity, but sufficient to exclude the forms of purely fresh water. Incidentally, the first indication of “concretionned limestones made of concentric scales” was reported by Omalius d'Halloy in 1812, and therefore prior to the observations of Steele [75]. So, the latter is not the discoverer of the future stromatolites of Kalkowsky.

The systematic status of Kelba, Savage, 1965, Kenyalutra, Schmidt-Kittler, 1987 and Ndamathaia, Jacobs et al., 1987, (Viverridae, Mammalia) and a review of Early Miocene mongoose-like carnivores of Africa

Abstract: The poorly known genera Kelba, Kenyalutra and Ndamathaia from Early Miocene deposits of East Africa are here considered to represent a single genus, Kelba , represented by an unique species Kelba quadeemae Savage, 1965 . As an assemblage the material resembles extant Hemigalinae more than any other carnivore group, and it is considered that the genus should be classified within the Viverridae. The family probably originated in South-East Asia and colonised Africa during the Early Miocene.

Distribution and palaeoecology of freshwater algae and stromatolites: III, some new forms from the Carboniferous, Permian and Triassic of France and Spain

Abstract: New collections allow us to describe some new algae forming: a) centimetric, unorganized, masses (Toutinella bifurcata from the Middle Triassic of Provence); b) large, decimetric masses (Zarramanella menorica from the ‘Buntsandstein’ of Minorca, Balearic Islands) and c) interesting, plurispecific biocenosis, laminated and silicified, from the French Massif Central: Lower Stephanian of Saint-Etienne basin (with Hankerpella minima, Baltzerella stephaniense, Ponsinella undulata) and Lower Autunian of Bourbon-l'Archambault basin (Hanskerpella pustulata, Baltzerella stephaniense, Ponsinella multifrons, Sarfatigirella intricata). Other forms are badly preserved, one is possibly a Broutinella sp. and another may be a coccoid form of cyanobacteria or chlorophyceae. Silicified biocenoses macroscopically occur in the form of regular laminations, exhibiting vertical, planar joints (1–2 cm wide) and horizontal, planar joints, 5 mm to 3 cm thick, with various sedimentary infillings. These facies represent early and late silicifications of biological felts (mats), probably previously partly calcified and affected by desiccation cracks partly infilled before the silicification. There is no evidence for an early silicification of living filaments and trichomes. The silicification also affects other types of sediments (petites, sandstones, conglomerates, breccias) associated with the algal formations. Macroscopically, these laminated formations do not show domes or hemispheres; on the other hand, these features clearly appear under the microscope, and these formations are true stromatolites. The basins of Saint-Etienne and Bourbon-l'Archambault contain volcanic rocks; the siliceous series, very localized in the basins, represent an impregnation of various primary materials by silica of hydrothermal origin. The present study is voluntarily limited to the palaeontological and palaeoecological appearances; algal laminations formed in ephemeral pools and small lakes, under very particular conditions, ‘hydrothermal’ sensu lato, are still to be stated more precisely.

Fossil spider's webs from the Namib Desert and the antiquity of Seothyra (Araneae, Eresidae)

Abstract: Several small, dome-like roughly ovate calcitic structures with lobed margins found in Miocene aeolianites of the Namib Desert resemble the clover-leaf shaped roof webs made by extant ‘trapdoor’ spiders of the burrowing genus Seothyra (Araneae, Eresidae). These webs consist of a mat of densely-woven silk with slits around the periphery, which is covered, on its upper surface, by sand. The fossils indicate that the genus Seothyra or a similar form of spider, has inhabited the Namib since the Miocene period, and that the capture ecology of the Seothyra type is an ancient one.

Hemicyon mayorali nov. sp., Ursidae du Miocène moyen de Tarazona de Aragon (bassin de l'Ebre, Aragon, Espagne)

Abstract: Study of a new species of an ursid, Hemicyon mayorali of Tarazona de Aragon in Spain. This species differs from the other species of the genus by the lengthening of the snout and the morphology of M2.

Nouvelles données paléontologiques sur le genre Dissimilites Sarkar, 1954

Abstract: A nearly complete specimen of a heteromorphic ammonite belonging to the genus Dissimilites Sarkar, 1954 (Ammonoidea, Ancyloceratina) has been collected in the Lower Barremian from south-east France. It is the first time that a such sample has been collected since the discovery by d'Orbigny in 1842 of the first specimens belonging of this taxon. Hypothetic until today, the existence of a spire in the first development of the shell is confirmed and a new diagnosis of the genus is given. Finally, the specific content of the genus is briefly analyzed as also its stratigraphical occurrence.

The systematic position of the Miocene grebe Thiornis sociata Navás

Abstract: Evidence is presented to show that dimensions and proportions which may vary with size are not valid characters for determining the generic placement of grebe species; that there is no valid reason for placing Thiornis sociata in the genus Podiceps; that if this species belongs in any Recent genus it is best placed in Tachybaptus, and that it is best retained in Thiornis pending further study.