The Aguille Formation (Coniacian-Santonian) of North of Gabonese coastal basin has been analysed from the 'Cap Esterias' section. Palaeoecologic and paleogeographic aspects of the bivalves were taken into account. Twelve bivalve species representing 9 genera have been identified from 'Cap Esterias' section. Among these Acanthocardia cf. denticula (Baily, 1855), Aphrodina dutrugei (Coquand, 1862) and Protocardia cf. pauli (Coquand, 1862) are found for the first time in the 'Cap Esterias' region. A large part (66.67%) of the identified bivalve species occur over a wide geographical area: from Brazil to Central Africa, eastern Mediterranean region, Madagascar, Nigeria, northwestern Africa, South Africa, southern India and southern Europe. The fauna is composed only of suspension-feeders indicating that food resources were dominantly in suspension. The assemblage of bivalves is dominated by shallow burrowing infaunal bivalves and indicates the existence of an unstable and soft substrate. This assemblage can be regarded as parautochthonous. RÉSUMÉLes Bivalves (Mollusques) du Coniacien-Santonien de la Formation de l'Anguille du Cap Estérias, nord du Bassin Gabonais ; notes sur la paléoécologie et paléogéographie. Les aspects paléoécologiques et paléogéographiques des bivalves de la Formation de l'Aguille (Coniacien-Santonien), au nord du bassin côtier gabonais, ont été analysées à partir de la coupe du « Cap Estérias ». Douze espèces de bivalves représentant neuf genres ont été identifées au niveau de cette coupe. Parmi elles, Acanthocardia cf. denticula (Baily, 1855), Aphrodina dutrugei (Coquand, 1862) et Protocardia cf. pauli (Coquand, 1862) sont signalés pour la première fois dans la région du « Cap Estérias ». Une grande partie (66,67 %) des espèces identifiées ont une large distribution géographique. Elles sont connues au Brésil, en Afrique centrale, à l'Est de la région méditerranéenne, à Madagascar, au Nigéria, au Nord-Ouest de l'Afrique, en Afrique du Sud, au sud de l'Inde et au sud de l'Europe. La faune est composée seulement des suspensivores. Ceci est l'indice de l'abondance de la nourriture en suspension. L'assemblage des bivalves est dominé par les épibiontes enfouis, ce qui indique un substratum instable et meuble. L'assemblage peut être regardé comme para autochtone.
The taxonomy and paleoecology of the Albian gastropods from the N’Toum quarry geological section (N’Toum locality) are here discussed. Three genera including four species are identified: Ampullina sp., Tylostoma pallaryi (Peron & Fourtau), Lithomphalus sp. A and Lithomphalus sp. B. Three morphotypes are identified as Aporrhaidae gen. et sp. indet., Gast. gen. et sp. indet. 1 and Gast. gen. et sp. indet. 2. The genus Lithomphalus as the rest of gastropods assemblage are reported for the first time in the Gabonese coastal basin. The gastropod fauna from the N’Toum quarry section is marine. Its composition suggests soft to firm substrate. The depositional environment is considered as within the shallow photic zone with probably high amounts of organic debris in the substrate.
A colony of macro-fossils Akouemma hemisphaeria has been described in the Paleoproterozoic sedimentary basin of Okondja, Gabon. These fossils are classified into two groups according to their spheroidal or elongated forms. The spheroidal shapes are similar, have a tripartite structure with two hemispheres and a median disc and gradually pass to the elongated forms. These elongated forms have a pronounced bipartite tendency to two "hemispheres" separated by a median surface, and often have several ovoid "pieces" attached. The elongated specimens show both lateral growth marks and signs of fission. Growth marks are characterized by unidirectional homogeneous side elongations and lateral bud-like protuberances. The signs of fission are marked by circular furrows perpendicular to the direction of elongation, called "constriction furrows" with varying depths depending on the degree of fission of the specimen and internal vertical "division planes". All of these ovoid and elongated specimens have undergone significant initial deformations due mainly to mutual lateral compressions in tabular beds. The Akouemma hemisphaeria macro-organisms, which were primitive probably sessile organisms, lived on How to cite this paper:
A study of Albian bivalves from Madiela Formation in north of Gabonese coastal basin has been carried out from N’Toum quarry geological section. Four genera including six species are identified: Liopistha (Psilomya) sp. 1, ? Liopistha (Psilomya) sp. 2, Megaporomya sp., Neithea (Neithea) dutrugei (Coquand, 1862), Pleuromya sp. 1 and Pleuromya sp. 2. One morphotype is identified as Bivalvia gen. et sp. indet. The genus Megaporomya Ayoub-Hannaa et al., 2013 and all identified species, except Neithea (Neithea) dutrugei (Coquand, 1862), are found for the first time in Gabonese coastal basin. Now, a total of twelve species of bivalves have been reported from the Madiela Formation. In Gabon, the presence for the first time of genera Liopistha and Pleuromya in N’Toum quarry geological section which is assigned to the Albian permits us to expand their geographical distribution until N’Toum region, and their age range to Albian.
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