Middle Jurassic (upper Bajocian) marine vetigastropods from the Western Saharan Atlas,Algeria

Whereas Middle Jurassic gastropods are very well known in Europe and other regions of the world, these faunas have been much less studied from northern Africa and most contributions available in literature have been based on relatively well-preserved material. Except a little lower Bajocian fauna from the Central High Atlas (Morocco) described at the turn of the 21th century, nothing is known about the Middle Jurassic gastropods of the southwestern Tethyan margin. The present paper aims to update the systematics of two vetigastropod species: Obornella cf. granulata (Sowerby, 1818) and Ambercyclus ornatus (Sowerby, 1819) recently found in the upper Bajocian succession of the Ksour Mountains (Tniet el Klakh Formation) at western Saharan Atlas (northern Algeria). The new Ambercyclus material found in well-preserved conditions confirms the absence of umbilicus in Ambercyclus; thus, we emend the original generic diagnosis. The specimens of Obornella cf. granulata and Ambercyclus ornatus represent the first occurrence of both genera and species in the upper Bajocian marine deposits of the western Saharan Atlas, and provide new taxonomic and palaeobiogeographic information about Middle Jurassic vetigastropods in Algeria.     

Cenomanian (Upper Cretaceous) bivalves from the Hameimat Massifs,north of Tebessa,Algeria: Systematics,biostratigraphy, palaeoecological and taphonomical remarks

In the eastern Saharan Atlas, particularly in the northern area of Tebessa Province (NE Algeria), the widely outcropping Cenomanian strata display a highly diversified macrofauna, among which bivalves are prominently represented. Twenty-eight bivalve species are here reported for the first time from the Cenomanian of Hameimat Massifs. Based on the stratigraphic distribution of these bivalves, five bivalve zones were recognized, i.e., Costagyra olisiponensis - Gyrostrea delettrei, Rhynchostreon suborbiculatum - Exogyra conica, Ceratostreon flabellatum, Ilymatogyra africana, and Pycnodonte vesicularis vesiculosa - Rastellum carinatum zones. Correlation to the ammonite biozones of the same region as follows: the Costagyra olisiponensis - Gyrostrea delettrei and the Rhynchostreon suborbiculatum - Exogyra conica zones occur respectively in the Sharpeiceras schlueteri and Mantelliceras saxbii subzones of the lower Cenomanian Mantelliceras mantelli Zone. The Ceratostreon flabellatum Zone is correlated with the middle Cenomanian Acanthoceras rhotomagense Zone. The Ilymatogyra africana Zone is correlated with the upper Cenomanian Calycoceras naviculare and the Metoicoceras geslinianum zones. Finally, the Pycnodonte vesicularis vesiculosa - Rastellum carinatum Zone represents the uppermost Cenomanian. Detailed analysis of biometrical and morphological features of these bivalve specimens provides the most reliable tool within the scope of palaeo-environmental reconstitution and the many palaeo-ecological variables that had driven the development and distribution of these macro-invertebrates. Comparison of these new data to those of adjacent south Tethyian areas supports the homogeneity of the Cenomanian bivalve faunas. Such an affinity underlines more vividly the favorable marine communications and currents driving the geographic dispersal of these bivalves during the Cenomanian.     

Torreites milovanovici Grubić, 1979, the first report of the Torreites genus in Iran

Late Cretaceous Torreites milovanovici, pertaining to Hippuritids (rudists) as marine heterodont bivalves, from SW Iran (northern Shiraz), is the centerpiece of this study. It is the first specimen of the Torreites genus recorded in Iran. More than 25 Torreites specimens were collected from the medium-bedded carbonate layer of the Upper Cretaceous succession of the study area. As well as in Iran, T. milovanovici specimens are recorded from Oman, and United Arab Emirates (UAE), although other species are found in Cuba, Jamaica, and Mexico. The Torreites-bearing bed is attributed to the clastic lower unit of the Tarbur Formation in Zagros Basin which is overlain by the carbonate upper unit of this Formation. Referring to field and laboratory observations as well as different previous references the Torreites-bearing carbonate layer in the study section can be ascribed to the Campanian. T. milovanovici specimens in Iran are compared with those recorded in Oman and UAE, using some determinative parameters. They show similarities in angles and size. Finding the species in a new area can be inspiring for future studies. It enhances the paleobiogeographical distribution of Family Torreitidae in the world and matching them chronologically can reveal some new evolutionary trends.     

Les Radiolaires d'âge jurassique supérieurà crétacé supérieur dans les Radiolarites du Pinde-Olonos (Presqu'île de Koroni; Péloponnèse méridional,Grèce)

Radiolarians of several radiolarites sections of the Pindos-Olonos zone, southern Peloponnesus, lead to propose direct datations of mesozoic sediments. The acuity of such datations allow to distinguish two periods for depositionof radiolarites s.s. in the tethyan region. The first period would be Upper Jurassic and general in tethyan realm, radiolarites depositing under various latitudes (0–35°N). This would be the result of a strong ocean surface current. The second period would be Upper Cretaceous (Vraconian—Coniacian) and be geographically much more restricted (0–15°N). This could result from a weaker current. The absence of radiolaritic sedimentation is possibly the result of the destruction or insulation of the accurate basins during the obduction of ophiolites on the apulo-african realm. The inventory of Late Cretaceous radiolarian fauna, rarely done on alpine series so far, shows similar result to those obtained in Central American and California.     

Le jurassique supérieur et le Crétacé inférieurd'Ankilizato (bassin de Morandava,Madagascar)

Upper Jurassic and Lower Cretaceous from Beritsa, near Ankilizato, are an important landmark between well known cross sections of Northern (Antsalova) and Southern (Sikily) parts of the Morondava Basin. New ammonites and belemnites fauna point out an Upper Jurassic to Upper Valanginian age for this section. A paleogeographical scheme shows the dynamical structure of «Ankilizato gulf at that time.     

Découverte de faunes d'Ammonites de la zone à Platynota(Kimméridgien inférieur) dans les Monts de Chellala (avant-pays Tellien,Algérie); Conséquences stratigraphiques et paléogéographiques

In Chellala mountains (Seba el Abiod), in Western Algeria, new biostratigraphic data, based on Ammonites, allow characterize, for the first time in North Africa, the Platynota zone with the species-index Sutneria platynota. This species was known, to the present time, only in the South European border. These new biostratigraphic data show the diachronism of flyschoid facies. They do not exceed middle Oxfordian in the Tlemcenian zone; on the contrary they go up to lower Kimmeridgian in the preatlasic zone.     

A new species of Lapparentophis from the mid-Cretaceous Kem Kem beds,Morocco, with remarks on the distribution of lapparentophiid snakes

Two isolated trunk vertebrae from the ?uppermost Albian–lower Cenomanian Kem Kem beds of Morocco are described and assigned to Lapparentophis, an early snake genus known from coeval deposits in Algeria. The Moroccan specimens represent a new species, Lapparentophis ragei, which can be distinguished from the type and only known species, Lapparentophis defrennei, by its smaller size, its more elongate vertebrae, the presence of parazygosphenal foramina, and paradiapophyses extending anteroventrally closer to the cotyle. The discovery of Lapparentophis in the Kem Kem beds adds to the relatively diverse snake assemblage previously reported from this formation and extends the geographical range of the genus. The distribution of Lapparentophis and lapparentophiid-grade (?lapparentophiid) snakes is discussed. This poorly known family of terrestrial snakes seems to be restricted to the latest Albian–early Cenomanian of North Africa, with the exception of Pouitella from the early–middle Cenomanian of France. As for many other vertebrate taxa of this period, this distribution is consistent with a dispersal event from Africa to the western part of the European archipelago.     

Foraminifères du Lias moyenet supérieur d'Obon: Chaînes ibériques,Province de Teruel,Espagne

The Obon sections in the central Iberian ranges, thestratigraphy of which is well established, have a rich microfauna of Foraminifera from Upper Domerian and Toarcian. It is partly original (4 new species are described, and 4 are left as open nomenclature).The plentifulness of the material has allowed thestructures of some of the populations to be shown up, some of the forms to be grouped up into spectrums and precisions brought in about the notion of the Lenticulina genus and its systematics.A part of the Iberian species is also to be found in the rest of Western Europe and Morocco. The Poitou species created by J.M. Payard (1947) are the objects of critical comparison. The later appearance of the marly-calcareous facies in Poitou may explain the differences in stratigraphic repartition fairly constantly observed.