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The taxonomic treatment of the Engonoceratoidea Hyatt, 1900 (Wright et al., 1996) is problematic and confusing, and recently has gained the attention of many paleontologists (Robert, 2002; Bujtor, 2010; Bulot, 2010; Latil, 2011). It appears that most of the described genera within this superfamily were based on morphological features, without stratigraphic and/or phylogenetic control. In particular, the genus Platiknemiceras Bataller, 1954, seems to represent a classic example of this problem. Knemiceras gracile Douvillé, 1916, from the Early Albian of Maghara area, north Sinai, Egypt, referred by Casey (1961) to Platiknemiceras, appears to be an often misinterpreted species. Species identified as members of the genus Platiknemiceras Bataller, 1954 in the literature, from Iran, Lebanon, Egypt, Tunisia, Algeria, Spain, France Peru, Colombia, Venezuela, USA and Japan are discussed herein, in order to revise their taxonomic positions. The type species, Platiknemiceras bassei Bataller 1954, is redescribed. A re-examination of the relationships between Knemiceras gracile and other members of the genus Platiknemiceras strongly suggests that this latter genus is polyphyletic.

Latil J.-L.,Le Maupas
Revue de Paleobiologie | Year: 2011

Nine sections were measured and studied in the Tadjerouine area (Central Tunisia), providing an abundant paleontological material. The historical collections of Pervinquière (1907) from Central Tunisia, Dubourdieu (Dubourdieu, 1949, 1953 and 1956 ; Breistroffer, 1953a ; Sornay, 1955) and Masse (Masse & Thieuloy, 1979) for the Ouenza area (Algeria) are revised and integrated to the paleontological and biostratigraphical study. A new regional biozonation on the basis of the ammonites is proposed for the Early Albian of Central Tunisia, revealing an almost complete and continuous succession from the base of the Albian to its top. Unfortunately, due to the lack of paleontological datas, the Aptian-Albian boundary cannot be defined. The ammonite succession allows precise correlations with the ammonite biozonation established in western Europe (Owen, 1999, 2002 ; Kennedy et al., 2000). The Hameima section (HMA) in Jebel Hameima, is herein considered as a regional reference which is completed by the Harraba section (HB) in Jebel Harraba for the lower part and Bou El Haneche section (BEH) in Jebel Bou El Haneche for the upper part. This biostratigraphical sequence is the most complete for the Early Albian of the South tethyan margins. An Earliest Albian detailed ammonite succession is recognized for the first time on the South Tethyan Margins. Three new ammonite genera are herein described : Hameimaceras gen. nov., Buloticeras gen. nov. and Mellegueiceras nov. gen. Nine species are new : Hameimaceras zghalae gen. nov., sp. nov. ; Pseudhelicoceras dubourdieui sp. nov. ; Douvilleiceras sp. nov. ? ; Mellegueiceras chihaouiae nov. gen., nov. sp. ; Mellegueiceras hameimaensis nov. gen., nov. sp. ; Mellegueiceras minutus nov. gen., nov. sp. ; Mellegueiceras jaillardi nov. gen., nov.sp. ; 'Hypacanthoplites' roberti sp. nov. and 'Hypacanthoplites' buloti sp. nov. These species all come from the earliest part of the Early Albian, revealing a high level of ammonite endemism on the central Tunisian platform. This endemism strongly declines with the Early Albian transgression.

Bulot L.,Aix - Marseille University | Latil J.-L.,Le Maupas | Vermeulen J.,Grand Rue | Aly M.,Cairo University
Geologica Carpathica | Year: 2011

The type material of the poorly known and monotypic genus Mogharaeceras is revised. Relationship with Pulchelliidae, Engonoceratidae and Barremitinae are discussed. All the available evidence suggests that Mogharaeceras is an offshoot of Barremitites and that it should be classified in the Barremitinae. New material from Egypt allows us to establish the Late Barremian age of this taxon.

Bulot L.G.,Aix - Marseille University | Latil J.-L.,Le Maupas | Hairabian A.,Aix - Marseille University | Fournillon A.,Aix - Marseille University
Proceedings of the Geologists' Association | Year: 2014

Nolaniceras nolani (Seunes, 1887) has been widely quoted in the Upper Aptian literature over the years. Re-examination of the holotype of the species shows that it has always been misidentified and that this taxon is represented by a single specimen, the holotype, of uncertain age. As a consequence, its use as an index species for the Upper Aptian should be reconsidered and abandoned. © 2014 The Geologists' Association.

Hfaiedh R.,University of Sfax | Arnaud Vanneau A.,Association Dolomieu | Godet A.,Association Dolomieu | Godet A.,University of Lausanne | And 6 more authors.
Cretaceous Research | Year: 2013

The Aptian sedimentary succession of the Chott region in southern Tunisia was deposited on the margin of the Saharan shield, and is punctuated by numerous hiatuses that separate seven 3rd-order depositional sequences. Early Aptian deposits correspond to the Berrani Member (early Bedoulian), which was deposited contemporaneously with the large carbonate platforms with rudists that developed under oligo-mesotrophic, tropical environmental conditions on both margins of the Tethys. Late Bedoulian sediments were deposited under mesotrophic conditions characterized by seagrass, algae, abundant orbitolinids and aragonite-producing organisms. The early to late Aptian transition was marked by the temporary disappearance of carbonate platforms and an important renewal of the microfauna, whose tests and skeletons became less and less aragonite-rich and more and more calcite-rich and arenaceous. This episode is reported from both Tethyan margins. The platform was subsequently flooded, and dysoxic environments with annelids marked the end of the early Aptian carbonate platform development. An arid and probably colder episode (earliest late Aptian) induced the deposition of gypsum in an intrashelf basin. Following on top, the return to more humid conditions triggered an enhanced input of detrital material in fluvio-deltaic environments (late Aptian). Finally, the return to oligo-mesotrophic, marine conditions allowed the temporary installation of wide lagoons with rudists in the latest Aptian and probably in the earliest Albian. Long-distance correlations have been established by means of benthic foraminiferal occurrences. They highlight the importance of stratigraphic gaps linked to low sea levels, which have been tentatively estimated.© 2013 Elsevier Ltd.

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