Heteromorph ammonites from the Tata Limestone Formation (Aptian–Lower Albian), Hungary

An important new ammonite fauna was collected by Fülöp in 1953 and 1960 from basal lenses between a Tithonian hardground and the overlying Tata Limestone Formation containing many heteromorph ammonites. This assemblage of ammonites has been determined as being of Early Albian ( tardefurcata Zone) age. Among the heteromorphs are species of Tonohamites and Ptychoceras , which are familiar components of Late Aptian or Early Albian ammonite faunas. The genera Ephamulina , Hamites and Protanisoceras are also recorded, the earliest species of which had previously come from sediments of late Early Albian ( mammillatum Zone) age. While Hamites and Protanisoceras are common in Europe, Ephamulina had previously only been known from Madagascar. The discovery of Ephamulina , Hamites and Protanisoceras supports the view that these phylogenetically significant ammonites had radiated close to the Aptian/Albian boundary. Four new species of Hamites ( H. czaszari , H. fazekasensis , H. fueloepi and H. kalvariensis ) and one new species of Tonohamites ( T. boldii ) are described.     

Cieneguiticeras, a new genus of Tithonian oppeliids (Ammonoidea, Late Jurassic)

The new genus Cieneguiticeras, assigned to the family Oppeliidae, is described on the basis of Andean lower-middle Tithonian ammonites from Arroyo Cieneguita, west-central part of the Neuquén-Mendoza Basin, Argentina. The macroconchs are closely homoeomorphic with Neochetoceras Spath and the microconchs have a ‘glochiceratid’-type morphology. The stratigraphic range of Cieneguiticeras nov. gen. includes the lower and middle Tithonian by means of a succession of two or three species which are interpreted as members of a phyletic lineage. Ammonites from the Tithonian of Cuba, Mexico and France are more or less confidently included in this new genus.     

Zapaliinae,a new subfamily of Tithonian–Berriasian ataxioceratid ammonites

The recent recognition of the earliest Andean Tithonian ammonite fauna (Picunleufuense Zone) has allowed a balanced classification of the ataxioceratid ammonites, reflecting their phylogenetic relationships. The Picunleufuense Zone fauna, first recognized in the Neuquén Basin at the base of the Vaca Muerta Formation, is represented by numerous records of sparse ammonite faunas from Antarctica, the Austral Basin and the Tarapacá Basin (N. Chile and S. Peru). These Southeastern Pacific faunas include the Tithonian genera Indansites, Choicensisphinctes, Zapalia, Krantziceras (Tithonian–lower Berriasian) and Platydiscus. These five genera are grouped in a new subfamily established in this paper: Zapaliinae subfam. nov. (type genus: Zapalia). The origin of Indansites and Choicensisphinctes (possibly via Indanistes) from Lithacoceras is discussed. Zapalia must have been originated from Indanistes in the upper Proximus Zone. Platydiscus could have been originated from Krantziceras. The Tithonian Southeastern Pacific ataxioceratids (Zapaliinae subfam. nov.) form a group well separated from the Tithonian Indo-Madagascan Virgatosphinctinae.     

Late Tithonian nannofossils from Dejen area,the Blue Nile Basin,central western Ethiopia

The Jurassic rocks exposed in the Blue Nile Basin (central western Ethiopia), particularly the thick, fossiliferous and widely distributed Antalo Limestone Formation (ALF) has recently been dated between early Callovian and late Tithonian based on the occurrence of calcareous nannofossils from the Mugher section near Dejen, Ethiopia. However, the top part of the ALF is not well exposed at Mugher; in this study, the top part of the ALF was sampled at the Kurar section (150 km north of Mugher). It yielded a nannofossil assemblage containing Helenea chiastia, whose first occurrence (FO) marks the base of the Tithonian NJT16a calcareous nannofossil subzone, and Faviconus multicolumnatus, whose FO is near the base of the NJ15b subzone and corresponds with the FO of the Tithonian zonal marker Polycostella beckmannii recorded at the Mugher section. This age is also corroborated by the presence of recently recorded calpionellids (Bonetinae subzone) and the presence of late Tithonian ammonites, Djurjuriceras cf. sinuosum Tavera and Oxylenticeras Spath from the Kurar section. Hence, the upper part of the ALF exposed at the Kurar and Mugher sections are of late Tithonian age, although at the Mertule Mariam section (60 km northwest of the Kurar section), late Berriasian calpionellids were recently found from the top part of the ALF.     

A refined ammonite biostratigraphy for the Middleand Upper Carixian (Ibex and Davoei Zones,Lower Jurassic) in North-West Europe and stratigraphical details of the Carixian-Domerian boundary

A refined biostratigraphical scheme is described forthe Ibex and Davoei Zones (Carixian Substage, Lower Jurassic) in NW Europe, and the biostratigraphical details of the Carixian — Domerian boundary are outlined. It is based on detailed stratigraphical collections of ammonites from the major Pliensbachian localities in Britain, France and Germany, with supplementary data from Portugal. The zones and subzones, which are largely unchanged from the well-established scheme described by Dean & alii (1961), are further divided into zonules which can be recognised throughout NW Europe. These zonules, nine for the Ibex Zone and seven for the Davoei Zone, probably represent the greatest biostratigraphical resolution readily obtainable using ammonite faunas. The problems inherent in the precise recognition of the chronostratigraphical Carixian-Domerian boundary, owing to slightly discordant species ranges, are discussed.     

Nouveaux repères biostratigraphiques à terebratulidés (Brachiopodes) dans le Tithonien inférieur ouest-européen

The discovery of a new species of Terebratulid (Xestosina sera nov. sp.) in the Lower Tithonian allows to specify the biostratigraphical subdivision of the Gigas Zone. This also allows to improve the correlations, when ammonites are lacking, among the Tithonian deposits of Aquitaine, the northern Jura and the eastern border of the Paris Basin. The critical revision of the Xestosina genus gives a nomenclatural setting argued to the index-species of biozones. It constitutes a brachiopods based parallel scale for the Kimmeridgian and Tithonian Stages.     

Caribbean Lower Tithonian ammonites from central-east Mexico

Imlay's ammonite species Paradontoceras butti and Paradontoceras antilleanum are first reported from central-east Mexico under precise stratigraphic control. Mexican and Cuban ammonites referred to these species have been studied and proved to have been gathered from a relatively limited area within the southern paleomargin of the north American Plate, which embraces eastern Mexico and north-western Cuba. The palaeontological examination, the multivariate analysis conducted on Mexican and Cuban data, the precise biostratigraphic and biogeographic control support the reinterpretation of Imlay's species P. antilleanum and P. butti. The latter has been designated the single, valid nominal species-level taxon which comprises the two species proposed by Imlay. The new genus Housaites has been created since the taxon Butticeras Houša is not available for taxonomic nomenclature. Housaites butti (Imlay) is upper Lower Tithonian (Semiforme/Verruciferum Zone of the Tethyan standard) in Mexico. The stratigraphic range in Cuba is not conclusively known.     

L'âge du complexe récifal des côtes de meuse entre verdun et commercy et la stratigraphie de l'oxfordien dans l'est du bassin de Paris

The question of the age of «Hauts de Meuse coral rag is studied again using new faunas of brachiopods and ammonites collected above, below and inside the coral rag. Ammonites fauna of the well known «Calcaires de Creuë is revised. Results obtained agree closely.The «Hauts de Meuse coral rag grew up during Middle Oxfordian time; and extend part of the Plicatilis zone (Antecedens Subzone) and the whole Transversarium Zone up to the basis of the Bifurcatus Zone, for the first time identified in Lorraine. So it span a short depositional time, about 1 MY, with a high deposition rate, the thickness of the coral rag being more than 100 meters, reaching 150 meters in Saint-Mihiel area. Towards SE, on the other side of the Marne Gap, the sudden change into basinal facies go with a reducing of thickness and deposition rate.Upper Oxfordian deposits show a relative uniformity of facies and thickness. At the top of Middle Oxfordian limestones, the age of the discontinuity and the Sequanian renewal of deposition is basal Bifurcatus Zone. Erosional renewal and terrigeneous deposits are a wide spread event by the beginning of Upper Oxfordian.In the paleontological part, species upon which are based new ages and interpretations are only figured, except the species new or with new paleontological data, which are described. Type specimen of Perisphinctes mosensisBayle, from the «Calcaires de Creuë, is described and photographically figured for the first time.     

LATE HETTANGIAN (EARLY JURASSIC) AMMONITES FROM TASEKO LAKES, BRITISH COLUMBIA, CANADA

Abstract: The Taseko Lakes area yields the most diverse and well‐preserved late Hettangian ammonite assemblage in British Columbia. In total, 27 ammonite taxa are described, of which Fergusonites hendersonae, Eolytoceras constrictum and Pseudaetomoceras victoriense are new. Based on this study, Phylloceras cf. asperaense Hillebrandt, Togaticeras togatum (Neumayr), T. aff. goisernense Rakús, Eolytoceras aff. guexi Taylor, Discamphiceras aff. silberlingi Guex, Schlotheimia cf. cuevitensis Hillebrandt and Franziceras aff. graylockense Taylor are newly recognized in the North American Mineralense Zone whereas Nevadaphyllites psilomorphus (Neumayr), N. aff. compressus Guex, Fergusonites hendersonae sp. nov., Eolytoceras chongi Hillebrandt, E. constrictum sp. nov., Paracaloceras spp. A and B, P.? spp., Metophioceras? sp. and Schreinbachites? aff. laqueoides (Hyatt) are newly recognized in the Rursicostatum Zone. Discamphiceras silberlingi, D. sp. nov., Alsatites aff. bipartitus (Hillebrandt), Alsatites sp., Pseudaetomoceras victoriense sp. nov. and Paracaloceras aff. varaense Hillebrandt are newly recognized in both the Mineralense and Rursicostatum zones. The Taseko Lakes fauna allows clear correlations with contemporaneous strata in other areas of North America as well as with the Canadensis Zone and probably the Arcuatum horizon of the South American succession. Broad correlations are also possible with Hettangian or lowest Sinemurian strata in New Zealand and the eastern Tethys. Furthermore, the Taseko Lakes fauna permits correlation of the Mineralense and Rursicostatum zones with the circum‐Mediterranean Marmoreum Zone. Finally, this fauna suggests that the Mineralense Zone and the lower to middle portion of the Rursicostatum Zone in Taseko Lakes are equivalent to the Complanata Subzone whereas the upper portion of the Rursicostatum Zone correlates with the Depressa Subzone of the north‐west European Angulata Zone.     

Ammonite and inoceramid radiations after the Santonian-Campanian bioevent in Sakhalin, Far East Russia

Study of several marine Santonian-Campanian successions from Sakhalin Island, Far East Russia, has revealed that evolution of the ammonites and inoceramid bivalves proceeded at different rates after the major faunal turnover at the (locally defined) Santonian-Campanian boundary. Sometimes changes in the inoceramid assemblages were more frequent and rapid than changes in the ammonite assemblages, and sometimes vice versa. Significant levels of inoceramid turnover and radiation events have been identified at the (locally defined) Santonian-Campanian and lower-upper Campanian boundaries. Changes in ammonite and inoceramid diversity, and in the proportions of endemic and cosmopolitan species, were investigated in the context of the local relative sea-level curve and inferred environmental changes. In Far East Russia, the main ammonite and inoceramid radiation after the local Santonian-Campanian faunal turnover occurred in the early Late Campanian Pachydiscus (P.) aff. egertoni ammonite Zone and the coeval Schmidticeramus schmidti inoceramid Zone. This condensed interval of ammonite and inoceramid maximum diversity provides a perfect stratigraphic marker that is recognizable in Sakhalin, North-East Russia and Japan. The succession of Santonian-Campanian assemblages identified in Sakhalin enabled the establishment of seven ammonite and six inoceramid zones, which correlate relatively well with those of North-East Russia and Japan. The problems of placing the Santonian-Campanian boundary in Sakhalin and in the adjacent Japanese island of Hokkaido are reviewed.     

Ammonite biostratigraphy of the uppermost Hauterivian in the Betic Cordillera (SE Spain)

A detailed analysis of the stratigraphic distribution of ammonites from fourteen sections in the External Zones of the Betic Cordillera has enabled us to identify accurately the sequence of bioevents that take place throughout the uppermost Hauterivian and to propose a more precise biostratigraphic scheme for this interval. Thus, we have divided the two currently admitted zones (the Crioceratites balearis Zone and the Pseudothurmannia angulicostata auct. Zone) into several subzones. Four subzones can be recognised within the Cr. balearis Zone. The base of each subzone is defined by the first occurrence of one of four successive species belonging to the same Crioceratites lineage. These species are: Cr. balearis, Cr. binelli, Cr. krenkeli and Cr. angulicostatus. The Ps. ohmi Zone (which replaces the classical Ps. angulicostata Zone) can be divided into three subzones characterised by three successive species of the genus Pseudothurmannia: Ps. ohmi, Ps mortilleti (here considered as a senior synonym of Ps. catulloi) and Ps. picteti. According to the current definition, the first occurrence of Taveraidiscus hugii (OOSTER) marks the lower boundary of the Barremian stage. This event fits into a major faunal-renewal episode that begins in the upper part of the Ps. picteti Subzone.     

Global radiolarian zonation for the Pliensbachian, Toarcian and Aalenian

Jurassic radiolarians from 220 samples in Queen Charlotte Islands, B.C., Williston Lake, B.C., east-central Oregon, Baja California Sur, southern Spain, Austria, Slovenia, Turkey, Oman, Japan and Argentina were studied in order to construct global zonation for the Pliensbachian, Toarcian and Aalenian stages. Well-preserved faunas from continuous stratigraphic sections in Queen Charlotte Islands provide the most detailed record for this time interval, and all collections are tied to North American ammonite zones or assemblages. Collections from nearly all other areas lack independent dating except for early Toarcian carbon-isotope dating in Slovenia and late Aalenian ammonites in Spain.A database of 197 widely distributed updated taxonomic species was used to construct a Unitary Association (UA) zonation for the interval. A global sequence of 41 UAs was obtained for the top of the Sinemurian to the base of the Bajocian. The first and the last UAs represent the Late Sinemurian and the Early Bajocian respectively. The remaining 39 UAs were merged into nine zones (four Early Pliensbachian, one Late Pliensbachian, one Early Toarcian, one Middle-Late Toarcian, and two Aalenian) according to prominent radiolarian faunal breaks and ammonite data. The new zones are the Canutus tipperi - Katroma clara Zone (latest Sinemurian/earliest Pliensbachian); Zartus mostleri - Pseudoristola megaglobosa, Hsuum mulleri - Trillus elkhornensis and Gigi fustis - Lantus sixi zones (Early Pliensbachian); Eucyrtidiellum nagaiae - Praeparvicingula tlellensis Zone (Late Pliensbachian); Napora relica - Eucyrtidiellum disparile Zone (Early Toarcian); Elodium pessagnoi - Hexasaturnalis hexagonus Zone (Middle and Late Toarcian); Higumastra transversa - Napora nipponica Zone (early Aalenian); and Mirifusus proavus - Transhsuum hisuikyoense Zone (late Aalenian). These zones can be correlated worldwide and link previously established UA zonations for the Hettangian-Sinemurian and the Middle to Upper Jurassic. The new zonation allows high-resolution dating in the studied interval and provides a solid basis for analyzing faunal turnovers and the paleobiogeography of Jurassic radiolarians.     

Reappraisal of the latest Albian (Mortoniceras fallax Zone) cephalopod fauna from the classical Salazac locality (Gard,southeastern France)

The Salazac locality (Gard, southeastern France) is renowned for the richness of its cephalopod fauna (especially ammonites) from the Mortoniceras fallax Zone (uppermost Albian, Lower Cretaceous). However, most ammonite species have paradoxically been scarcely illustrated up to now. Furthermore, the rare assessments of ammonite taxonomic diversity are presumably inaccurate, as they either result from a drastic typological approach or could not benefit from the most recent advances in modern concepts of ammonoid intraspecific and ontogenetic variations. In this work, we document an original cephalopod assemblage from Salazac represented by abundant, well-preserved specimens (564 studied ammonites, including ca. 50% of heteromorphs) constituting a high diversity. The sample size and quality of this new material allowed some extensive morphological and biometric analyses whenever possible (i.e., for subdatasets in which a significant number of measurements is available) and to thoroughly assess intraspecific and ontogenetic variations for a few species. This led to determine the diagnostic value of various shell characters commonly used to characterize both well-documented and poorly-defined species. In particular, we show that a significant part of the variation in the number of ribs per whorl within the heteromorphic genera Mariella and Turrilitoides is directly related to shell size and that the strength of tubercles covaries negatively with the number of ribs in Mariella, therefore challenging the diagnostic value of these characters. We further suggest that rib density covaries with whorl shape in Mariella, following Buckman’s first rule of covariation. In total, one species of nautilid and 38 taxa (25 genera) of ammonites are described, among which five species are documented from Salazac for the first time. In turn, this study provides valuable data for future phylogenetic, biostratigraphical, biogeographical and broad-scale diversity studies.     

A new mode of ammonite preservation – implications for dating of condensed phosphorite deposits

Unusual phosphatic casts of the ammonites Mortoniceras (Subschloenbachia) sp. and Stoliczkaia sp. from the upper Albian condensed phosphorite bed at Annopol, Poland, are discussed in terms of their taphonomic history. These specimens are interpreted as ‘secondary’ external casts of ammonite replicas preserved originally as attachment scars on oyster shells. The following genetic history is suggested for this previously undocumented mode of ammonite preservation: (1) settling of shells of dead ammonites on the seafloor; (2) colonization of these shells by oysters and formation of ammonite replicas on left valves of oysters; (3) dissolution of ammonite shells; (4) reworking and fragmentation of oyster shells; (5) casting of ammonite replicas by phosphatic material; and (6) separation of ammonite casts from oyster shells, either through mechanical disintegration or dissolution of the latter. The specimens studied were formed after dissolution of the ammonite conchs, not prior to this event as in the case of typical ammonite steinkerns (internal moulds). Therefore, they are here referred to as ‘pseudo‐steinkerns’. The time interval between loss of the original ammonite shells and the formation of oyster‐mediated pseudo‐steinkerns may be very extensive. Therefore, the pseudo‐steinkerns may potentially mislead in biostratigraphic dating of condensed phosphorite deposits.     

THE EARLY JURASSIC AMMONITE BADOUXIA FROM BRITISH COLUMBIA, CANADA

Abstract:  Most species of the Lower Jurassic ammonite genus Badouxia are restricted to the eastern Pacific where they are of fundamental importance to the Hettangian/Sinemurian ammonite zonation of North America. The fauna from the type area for the genus has been restudied and four species and two transitional forms are now recognized. Badouxia forticostata and Badouxia castlensis are new. Badouxia occidentalis (Frebold) and Badouxia oregonensis Taylor are placed in synonymy with Badouxia canadensis (Frebold). These major taxonomic changes and subsequent modification to the range of B . canadensis require revisions to the current zonation for the Western Cordillera of North America. The Oregonensis Zone is re-named the Mineralense Zone. The Canadensis Zone is abandoned and its previously defined Rursicostatum and Columbiae subzones are elevated to the level of full zones. Large samples indicate that most species of Badouxia display a remarkable range of continuously variable morphology. In addition, the genus shows some of the best-documented evidence of sexual dimorphism in Early Jurassic ammonites. Badouxia spans the Hettangian/Sinemurian boundary and based on the range of different species, five stratigraphic intervals are recognized. Intervals 1–3 correlate with the north-west European Angulata Zone. The majority of interval 4 and the whole of interval 5 correlate with the north-west European Bucklandi Zone. The age of the base of interval 4 is uncertain.     

Les faunes de Cardioceratinae (Ammonoidea) du Callovien terminal et de l'Oxfordien inférieur et moyen (Jurassique) de la Suisse septentrionale: Stratigraphie,paléoécologie,taxonomie préliminaire

The first photographs of Cardioceratinae out of exactly defined horizons from the Latest Callovian to the Middle Oxfordian of northern Switzerland are given in this article. Most specimens were either collected in large-scale excavations, or from measured sections. The Cardioceratinae from the Cordatum Subzone are important because they are very numerous, and because particularly well-preserved specimens are abundant. Cardioceratinae of this subzone are uncommon elsewhere in Europe. All representatives of the subfamily from the Cordatum Subzone, macro- as well as microconchs, are grouped into the single genus Cardioceras. An abrupt morphological change has been recognized between the Cardioceratinae of the Densiplicatum Zone and those of the Transversarium Zone.Most of the figured specimens have been found in an incomplete sequence of thin or even condensed horizons. These beds are the distal, starved basin facies of a thick, argillaceous, shoaling-up succession in northwestern Switzerland. Sedimentologic and taphonomic methods have been used in order to work out the time sequence of sediments and ammonite faunas in condensed beds, and to arrive at a correct zonation. These methods as well as observations on the distribution of chamosite and glauconite, and the ammonite assemblages, in two coeval horizons lead us to the conclusion that the Cardioceratinae of the Cordatum Subzone in northern Switzerland lived preferentially in water less than about 100 m deep.     

Proposed validation of the specific namescrenatus Bruguière, 1789, andrenggeri Oppel, 1863 (Class Cephalopoda,Order Ammonoidea) from the Oxfordian stage of the upper jurassic

Ammonites crenata Bruguière (1789) is one of the oldest species names used in modern ammonite taxonomy. This is a nomen dubium that is probably a synonym of what modern authors callCreniceras renggeri (Oppel 1863), a common species of the early Oxfordian.Ammonites crenatus Bruguière in Oppel (1863) is a stratigraphically junior taxon of the middle Oxfordian. Nevertheless, there is a possibility, however improbable it may be, thatAmmonites crenata Bruguière andAmmonites crenatus Oppel are synonyms. Therefore it is proposed here to retain the current usage of the namescrenatus Bruguière emend. d’Orbigny (1847) andrenggeri Oppel.     

Late Volgian <Emphasis Type="Italic">Kachpurites</Emphasis> Spath (Craspeditidae,Ammonoidea) of the Russian platform

Ammonites of the genus Kachpurites are characteristic of the lower part of the Upper Volgian Substage of the Russian Platform. K. fulgens fulgens (Trautschold), K. fulgens tscheremkhensis Mitta et al., K. subfulgens (Nikitin) are established in the fulgens zone. The genus Kachpurites also includes ammonites previously described as Anivanovia mola Kiselev. The holotype of Volgidiscus singularis Kiselev belongs to K. mola, wheras some of its paratypes belong to Craspedites krylovi Prigorovsky. The generic name Anivanovia Kiselev, 2003 is considered as a junior subjective synonym Kachpurites Spath, 1924. The beds with Kachpurites mola are in the basal part of the Upper Volgian subditus Zone. Species of the genus Kachpurites are described, and macro- and microconchs are established within the species.     

Toarcian ammonites of the Polymorphum Zone,Amellago area (eastern central High Atlas), Morocco,with a discussion on ammonite turnover events

In the Amellago area (central High Atlas), the widely distributed Toarcian succession consists of marls and marly limestones of the Tagoudite and Agoudim formations. We here describe, for the first time, the ammonites of the Polymorphum Zone from the Tagoudite Formation, including Canavaria cf. rosenbergi Fucini, C. aff. zancleana (Fucini), Dactylioceras (Eodactylites) mirabile (Fucini), D. (E.) aff. mirabile (Fucini), D. (E.) pseudocommune Fucini, D. (E.) simplex (Fucini), D. (Orthodactylites) aff. crosbeyi (Simpson), Lytoceras gr. villae Meneghini, Neolioceratoides cf. hoffmanni (Gemmellaro) and Praepolyplectus sp. This ammonite assemblage is closely correlated with those reported from the Polymorphum Zone of several basins of the Tethyan margins and the Northwest European Subboreal Realm, indicating marine communications between the different Moroccan Jurassic basins and the central Atlantic trough. The overlying Agoudim Formation yields ammonites of the Levisoni Zone in its base and rare ammonites of the Bifrons Zone in the middle part. Four significant changes in the ammonite assemblages during the early-middle Toarcian and their probable causes are also discussed.     

Les formations du jurassique supérieur du Bou Rheddou au Nord de Tiaret (Bordure sud-Tellienne,Algérie): âge et milieux de dépôt

In the Bou Rheddou mountain (Southern Tellian border), new biostratigraphic data based on Ammonites, allow precise and modify the age of the Arkell & Busson formations. The Oxfordian «Ammonitico rosso facies begin in the Transversarium zone and go into the Planula zone. This zone is characterized for the first time in this region. Lower Tithonian (Hybonotum zone) and Upper Tithonian (Microcanthum zone) are also recognized. Precisions on depositional environment and paleogeography are given. Facies and low sedimentation show a pelagic shoal (abundant planctonic organisms) slightly subsiding and lately recovered by the Jurassic transgression. During Oxfordian, episodic interruption of the «Ammonitico rosso deposits shows an unstable period with terrigenous deposits (intra-oxfordian tectonic movements). The facies of the Northern-Gondwanian carbonated platform begin earlier in the Bou Rheddou zone (Oxfordian-Kimmeridgian boundary) than in the Southern regions, where the same facies appears only in Upper Kimmeridgian.