Résumé: Environmental changes can impact benthic fauna at multiple levels. To better understand these changes at both the species and community levels, the Cenomanian macrofossils from two regions in northeastern Algeria, Tebessa and Batna, were analyzed. The results revealed that while changes at the species level (morphology) and community level (ecology) followed similar patterns, they were not identical. Non-metric multidimensional scaling (NMDS) and permutational multivariate analysis of variance (PERMANOVA) tests of the morphological variations of 114 complete shells of the suspension-feeding trigonoid bivalve Scabrotrigonia scabra (Lamarck, 1819) showed significant differences (P < 0.001) between the two regions. Two distinct echophenotypes were identified, with the first dominating in T´ebessa and the second in Batna. The Batna echophenotype is characterized by smaller, flattened shells with numerous ribs, an adaptive strategy for stabilizing in soft substrates. Additionally, the smaller shells in Batna were linked to the oligotrophic conditions of the outer ramp setting, in contrast to the deeper outer ramp setting in T´ebessa (mesotrophic). To further investigate environmental variations, the macrofaunal associations of the Cenomanian were examined. The NPMANOVA test indicated significant differences in faunal associations between the regions, with Batna exhibiting less diversity and a higher proportion of deposit-feeders, suggesting soft substrate conditions. In contrast, no significant differences were found among the faunal associations of the different Cenomanian substages, though ecological attributes showed minor, gradual changes. The early and middle Cenomanian fauna were dominated by epifaunal byssate taxa, while deposit-feeder taxa increased in the late Cenomanian, likely due to the global sea-level rise toward the end of the period. Overall, the paleogeographic setting (middle versus outer ramp) appears to have played a major role in shaping the ecological and morphological variations between T´ebessa and Batna.

Résumé: Twenty-one gastropod species are identified from the Cenomanian deposits of Bellezma-Aures mountains, eastern Saharan Atlas, Algeria. Among of these taxa four species [Tylostoma elevatum (Shumard), T. torrubiae Sharpe, Nerinea olisiponensis Sharpe and Calliomphalus orientalis Douvill´e] are recorded for the first time in the mounts of Batna. These gastropods taxa are found scattered in the ‘Marnes de Smail’ Formation and their community changes can be attributed to minor sea-level fluctuation associated to variation in the sedimentation rate and hydrodynamics. Furthermore, the palaeobiogeographic distribution of these gastropod assemblages display tethyan affinity and their subsequent faunal exchange in that time interval.

Résumé: The Coniacian strata of the T´ebessa Mountains in northern Algeria are predominantly marly facies that have received few studies. The present study is the first one to be carried out at Djebel Essen (west of T´ebessa) to reveal the paleoenvironmental setting. The macrofossil taxa identified herein include fifteen bivalve species, three gastropods, and one cephalopod species, in addition to four irregular echinoid species. Quantitative analysis of these macrofossils indicates the occurrence of three benthic Coniacian macrofaunal associations, which include: 1) Agelasina plenodonta, 2) Cucullaea, and 3) Oscillopha-Plicatula. Both Agelasina plenodonta and Cucullaea associations are dominated by infauna. However, Cucullaea Association contains only suspensionfeeders, where deposit-feeders are completely absent, suggesting oligotrophic conditions, that might have resulted in the lowest diversity level. In contrast, epifaunal taxa dominated the Oscillopha-Plicatula association. All the three associations are paucispecific. This low diversity of the Coniacian associations at study area and in other North African countries, can be attributed to the retreat of the sea and the shrinking of shallower habitats’ area. Probably, these associations lived within restricted marginal marine environments. The absence of any potential indicator of the middle-upper Coniacian anoxic event (OAE-3) agrees with the case in nearby sections and confirms a restricted extent of this event. The occurrence of many taxa of either regional or cosmopolitan affinity suggests episodic connection with the Tethyan Ocean.

Résumé: From 700 echinoids specimens collected from the Cenomanian sediments of Batna Mounts, 16 species (9 regular and 7 irregular) belonging to 11 genera, 10 families and 7 orders, have been identified. One species is reported for the first time from Algeria Pygaulus subaequalis. The irregular echinoids, including the Hemiasteridae remain the most abundant. The abundance, biodiversity and distribution of the echinoids in the Cenomanian deposits leads to recognize echinoid assemblages or echinoid biozones closely related to sea level variation. The identified echinoid biozones are as the following (1) a lower Cenomanian association representing the Hemiaster gabrielis Total Range Zone (Association A) characterizing a relatively deep environment, located distally in the platform; (2) a middle Cenomanian association which comprises the Mecaster aumalensis - M. pseudofourneli Assemblage Zone (Association B) representing a shallower marine environment; (3) two associations in the upper Cenomanian Mecaster batnensis Acme Zone (Association C1) and the first occurrence of the holectypoids (Association C2) which indicates slight bathymetric fluctuation between the lower and upper infralittoral zones; (4) towards the terminalCenomanian, the Mecaster cf. heberti Total Range Zone (Association D), corresponds to a shallow subreefal environment.

Résumé: The Cenomanian of the Batna region (NE Algeria) contains highly diversified macro-invertebrate fossiliferous deposits, often in a good state of preservation. The genus Myoconcha dates from the Carboniferous to the Cretaceous and essentially inhabits the North bank of the Tethys. Here, we record it for the first time in the middle Cenomanian levels of Batna with the species Myoconcha cretacea. The presence of this species would indicate a shallow but mostly quite turbulent environment.

Résumé: In the northern Aurès Range near Batna, Algeria, the Cenomanian Smail Marls Formation consists of fossiliferous deposits rich in diverse benthic macrofauna,mostly dominated by bivalves,among themthe carditid Maghrebella forgemoli (Coquand, 1862). Almost exclusively Cenomanian, the abundance zone of Maghrebella forgemoli is in the higher levels of Lower Cenomanian, extending from the Sharpeiceras schlueteri zone to the Mantelliceras dixoni zone and corresponds to a limited circalittoral interval with relatively low energy, soft substrata, and relatively cold temperatures. The distribution of Maghrebella forgemoli inMountains of Batna evidences bathymetric variation controlled by the tectonic activity affecting the ante-Triassic and the Upper Cretaceous substrata and generating a system of tilted blocks, at the beginning of the uppermost Albian-Cenomanian and Turonian, in the eastern Atlasic domain that extends to central Tunisia.

Résumé: In the Batna area of Algeria, the Cenomanian is represented by the Smail Marls Formation, a highly fossiliferous unit with a diverse benthic macrofauna (mainly of ostreid bivalves). A total of 1090 specimens belonging to 65 macrobenthic species were identified from 19 stratigraphic samples. The macrofaunal communities were quantitively analyzed using the hierarchical clustering (HC), nonmetric multidimensional scaling (NMDS), and permutational analysis of variance (PERMANOVA). Five distinct associations are recognized: 1) Costagyra olisiponensis, 2) Rhynchostreon suborbiculatum, 3) Aspidiscus cristatus, 4) Rhynchostreon suborbiculatum-Mecaster ameliae, and 5) Pycnodonte vesicularis. Data suggests that during the Cenomanian, the dominance of high-energy opportunistic oyster species within the soft marly sediments are related to their adaptive strategies. The changes noted in the community structure are attributed to sea-level fluctuations, rate of sedimentation and the prevailing hydrodynamics. Towards the uppermost Cenomanian and the CenomanianeTuronian boundary, the oysters become rare due to eustatic sea-level rise and this decline coincides with increasing predation intensity on oysters and the destruction of their shallower habitats.

Résumé: éLes niveaux inférieurs du Cénomanien de la région de Batna (NE, Algérie) constituent la partie du Céno-manien la plus riche et la plus diversifiée en matière de macro-invertébrés, essentiellement dominés parle groupe des bivalves en termes de spécimens et de taxons. Parmi les bivalves, les Crassatellidae sontexclusivement présents dans les niveaux inférieurs du Cénomanien et représentés par la seule espèceCrassatella baudeti. Cette dernière, facilement identifiable par sa forme d’ancre, et ses lamelles commargi-nales assez fortes, s’avère très abondante. Elle est présente dans les niveaux compris depuis la sous-zoneà Sharpeiceras schlueteri jusqu’à la zone à Cunningtoniceras inerme. Cette espèce est, par conséquent,un bon marqueur des derniers niveaux du Cénomanien inférieur et le début du Cénomanien moyen.Une description paléontologique et une discussion environnementale précises ont été réalisées. Ainsi,Cr. baudeti serait révélatrice d’un environnement peu profond, avec des eaux froides mais calmes, unesalinité normale et un substrat modérément mou. Retrouvée uniquement dans quelques sites téthysiens,la présence exclusive de Cr. baudeti dans le Cénomanien reflète un gradient thermique et une zonationclimatique spécifiques.

Résumé: In the Batna Mountains, the Cenomanian Marnes de Smail Formation yield fossiliferous deposits mostly dominated by bivalves. Thirty-five bivalve species were identified, belonging to nine orders, 19 families and 26 genera. Five of them are mentioned for the first time from the Cenomanian of the study area (i.e., Nucula ? cf. margaritifera Douvillé, Barbatia (Barbatia) aegyptiaca Fourtau, Cucullaea trigona Seguenza, Arctica inornata d’Orbigny, and A. cordata Sharpe). Their distribution provided interesting insights on the marine paleoenvironment of the Cenomanian times. The paleobiogeographic distribution of the studied bivalves corresponds to the Tethys Realm.

Résumé: The ichnological study of the Djebel Bouarif Cenomanian deposits (Northern Aurès Range, Algeria) revealed relatively abundant and diverse sclerobiont communities that are preserved in corals, bivalves and gastropods. Fossil traces are dominated by exceptionally preserved Gastrochaenolites, often with tracemakers (bivalves), which are preserved in situ, Entobia, and Maeandropolydora. Other borings are rare and are represented by a single specimen of Rogerella, Nihilichnus, and Spirolites. Among sclerozoans, encrusting juvenile oysters and non-oyster bivalves (Pseudolimea? granulata) are the most abundant groups. Other epibionts, such as gastropods and polychaetes (Glomerula serpentina), are less common; dwarf gastropods were located on a single oyster Costagyra olisiponensis, whereas Glomerula specimens were clustered on the lower and upper surfaces of coral Aspidiscus cristatus. Gastrochaenolites with original tracemakers and all the epibionts studied herein have not been described from the Djebel Bouarif Cenomanian deposits to date. The rare occurrences of Spirolites and Nihilichnus are reported from Algeria for the first time.

Résumé: tIn the eastern Saharan Atlas, particularly in the northern area of Tebessa Province (NE Algeria), thewidely outcropping Cenomanian strata display a highly diversified macrofauna, among which bivalves areprominently represented. Twenty-eight bivalve species are here reported for the first time from the Ceno-manian of Hameimat Massifs. Based on the stratigraphic distribution of these bivalves, five bivalve zoneswere recognized, i.e., Costagyra olisiponensis - Gyrostrea delettrei, Rhynchostreon suborbiculatum - Exogyraconica, Ceratostreon flabellatum, Ilymatogyra africana, and Pycnodonte vesicularis vesiculosa - Rastellumcarinatum zones. Correlation to the ammonite biozones of the same region as follows: the Costagyraolisiponensis - Gyrostrea delettrei and the Rhynchostreon suborbiculatum - Exogyra conica zones occurrespectively in the Sharpeiceras schlueteri and Mantelliceras saxbii subzones of the lower CenomanianMantelliceras mantelli Zone. The Ceratostreon flabellatum Zone is correlated with the middle CenomanianAcanthoceras rhotomagense Zone. The Ilymatogyra africana Zone is correlated with the upper CenomanianCalycoceras naviculare and the Metoicoceras geslinianum zones. Finally, the Pycnodonte vesicularis vesicu-losa - Rastellum carinatum Zone represents the uppermost Cenomanian. Detailed analysis of biometricaland morphological features of these bivalve specimens provides the most reliable tool within the scopeof palaeo-environmental reconstitution and the many palaeo-ecological variables that had driven thedevelopment and distribution of these macro-invertebrates. Comparison of these new data to those ofadjacent south Tethyian areas supports the homogeneity of the Cenomanian bivalve faunas. Such an affin-ity underlines more vividly the favorable marine communications and currents driving the geographicdispersal of these bivalves during the Cenomanian.

Résumé: The Cenomanian Smail Marl Formation in the Bellezma and Aures mountains of northeastern Algeria is well exposed and rich in macroinvertebrates, including cephalopods. Twenty-five ammonite species and two nautiloid species from the Thénièt El Manchar, Djebel Metrassi and Djebel Bouarif sections are described and seven assemblage zones proposed as provisional working units: Mantelliceras mantelli–Sharpeiceras laticlavium Assemblage Zone (lower Cenomanian), Mantelliceras dixoni Assemblage Zone (uppermost lower Cenomanian), Cunningtoniceras inerme Assemblage Zone (lower middle Cenomanian), Acanthoceras rhotomagense and Acanthoceras cf. rhotomagense Assemblage Zone (middle middle Cenomanian), Acanthoceras amphibolum Assemblage Zone (upper middle Cenomanian), Acanthoceras jukesbrownei Assemblage Zone (uppermost middle Cenomanian), and Neolobites vibrayeanus Assemblage Zone (lower upper Cenomanian). The lower Cenomanian Mantelliceras mantelli–Sharpeiceras laticlavium Zone is subdivided into the Submantelliceras aumalense, Sharpeiceras schlueteri and Mantelliceras saxbii subzones. The base of the middle Cenomanian is marked by the disappearance of species of Mantelliceras and the appearance of the scleractinian coral Aspidiscus cristatus (Lamarck, 1801), associated with Cunningtoniceras inerme (Pervinquière, 1907). The middle Cenomanian contains abundant A. cristatus and species of Acanthoceras, i.e., A. cf. rhotomagense (Defrance in Brongniart, 1822), A. jukesbrownei (Spath, 1926) and A. amphibolum Morrow, 1935. An ammonite zonal scheme is then applied to the Cenomanian exposed in the Bellezma-Aures mountains located on the southern Tethys margin in Algeria.

Résumé: Situés au nord de Tébessa (Atlas saharien oriental), les massifs de Hameimat Nord (HN) et de Hameimat Sud (HS) comportent de vastes affleurements cénomaniens riches en macro-invertébrés marins. Parmi les ammonites récoltées, 15 espèces sont décrites et identifiées. L’analyse biostratigraphique de ces ammonites permet d’établir une subdivision du Cénomanien de Hameimat. Quatre biozones y sont reconnues : Zone à Mantelliceras mantelli (partie moyenne du Cénomanien inférieur), Zone à Acanthoceras rhotomagense (partie moyenne du Cénomanien moyen), Zone à Calycoceras naviculare (base du Cénomanien supérieur) et Zone à Metoicoceras geslinianum (partie moyenne du Cénomanien supérieur). La Zone à Mantelliceras mantelli peut être scindée en deux sous-zones : Souszone à Sharpeiceras schlueteri et Sous-zone à Mantelliceras saxbii. La comparaison des résultats obtenus avec les données des régions avoisinantes (Boukhadra, Morsott et Ouenza) permet de compléter la biozonation locale. Elle révèle également d’étroites similitudes avec les assemblages du Kalaat Senan (Tunisie) et du NW de l’Europe. La répartition géographique assez large de ces ammonites durant le Cénomanien atteste d’une homogénéité faunistique et d’une appartenance à un même domaine paléobiogéographique ; elle permet alors de préciser les corrélations entre les deux marges du domaine téthysien.

Résumé: Les marnes cénomaniennes de la région de Batna (nord-est de l'Algérie) montrent plusieurs niveaux fossilifères, à faune très diversifiée. Parmi les fossiles présents en abondance et en bon état de conservation figure Aspidiscus cristatus (LAMARCK, 1801). Cette espèce de polypier a été rattachée à la famille des Latomeandridae ALLOITEAU, 1952, en raison de la présence de pennulae et de perforations concentrées sur le bord interne des septes. Dans les coupes étudiées, Aspidiscus cristatus se rencontre dans des niveaux allant de la Zone à Cunningtoniceras inerme à la Zone à Acanthoceras amphibolum, avec une relative abondance dans la Zone à Acanthoceras cf. rhotomagense. Cette espèce est, par conséquent, un bon marqueur du Cénomanien moyen de la région de Batna. Nous donnons ici une description paléontologique et discutons des cadres environnemental et paléogéographique de cette espèce. En effet, la morphologie externe de son test, convexe sur la face supérieure, plane à concave sur la face inférieure, évoque une adaptation à des environnements marins de faible énergie, de substrat vaseux et au taux de sédimentation élevé. La répartition paléogéographique de cette espèce, avec des spécimens de taille souvent plus grande sur les marges sud et est du domaine téthysien que sur la marge nord, témoigne d'un gradient thermique et d'une zonation climatique spécifiques, avec des eaux relativement plus chaudes sur la marge sudtéthysienne au Cénomanien, favorisant une bio-érosion beaucoup plus fréquente et plus poussée des spécimens fossiles des régions sud-téthysiennes que celle affectant les spécimens des régions septentrionales de la Téthys.

Résumé: A rich paleontological assemblage was collected in the Cenomanian deposits of the Djebel Metrassi (Batna, NE Algeria). It consists of 327 specimens assigned respectively to a single coral, 24 bivalve, 14 gastropod, 3 ammonite, and 7 echinoid species. This macrofaunal association leads us to establish an original taxonomical reference list along with several species new for the Cenomanian of this area, and supports the lithostratigraphic framework herein proposed.

Résumé: Rare earth element (REE) analyses are reported on glauconite-bearing phosphorites from northeastern Algeria. These rocks of Paleocene-Eocene age are located in the Eastern part of the Saharan Atlas, where two localities were investigated: the Djebel El Kouif in the north and the Kef Essenoun in the south. The latter belongs to the world-class Djebel Onk mining deposit. Petrographic examination indicates that phosphorite from the main layer of the Kef Essenoun deposit has a significant abundance in glauconite grains, while their occurrence in the Djebel El Kouif is restricted to the basal levels. In both deposits, glauconite grains are richer in REEs than other coexisting particles (pellets, coprolites, enameloid and dentine of marine fish teeth), but the glauconites of the Kef Essenoun deposit exhibit significantly higher REE concentration (min=654 ppm, max=1760 ppm, average=1146 ppm) than those of Djebel El Kouif deposit (min=543 ppm, max=623 ppm, average=584 ppm). The whole-rock REE concentrations also show substantial differences between the two deposits and the REE enrichment in the Kef Essenoun main sub-layer is more likely the result of the high glauconite content. PAAS normalized-REE patterns of the glauconite grains display similar patterns between the northern and southern localities with weak negative Ce anomalies and slight middle REE enrichments. On the other hand, the pellets and whole phosphorite grains from the northern deposit indicate a REE source from oxicsuboxic seawater, whereas those from the Kef Essenoun deposit exhibit slight middle REE enriched patterns with weak negative Ce anomaly suggesting a different environment of deposition (i.e. a tendency to reduced conditions). These geochemical results along with previous petrographic studies confirm the allochthonous character of the main phosphorite sub-layer in Kef Essenoun, where winnowing, transport and re-deposition of previously deposited phosphorites resulted in high accumulation and formation of glauconite grains. The glauconitization process of fecal pellets happened in two stages and was controlled by semi-confined microenvironments. This can explain the abundance of glauconite grains in the phosphorites from Kef Essenoun deposit and their restricted occurrence in the basal levels of the Djebel El Kouif outcrop.

Résumé: This study deals with the preliminary data of rare earth elements (REE) obtained on northeastern Algerian phosphorites from the Tébessa region. These phosphorites are located in two different basins: the northern basin represented by Dj. El Kouif, Dj. Dyr and Tazbant showings and the southern basin with the giant Dj. Onk phosphate deposit. The host sedimentary formation is Late Paleocene to Early Eocene. Twenty-six (26) samples from the four (4) localities were collected and analyzed for their REE contents using the ICP-MS technique. Phosphates from the southern basin (Dj. Onk deposit) show ΣREE contents ranging from 174.41 and 906.39 ppm (average ΣREE = 623.01 ppm), while the northern phosphorites have lower ΣREE contents (from 125.45 to 472.44 ppm; average = 265.57 ppm). PAAS-normalized REE patterns and binary Box plot of (Sm/Pr)N vs (Sm/Yb)N show HREE enrichments for samples from the northern localities while most samples from the southern basin are HREE depleted. Normalized (La/Yb)N vs (La/Sm)N plot shows that (La/Sm)N ratios of all samples are similar to those of modern seawater (from 0.83 to 1.55). However, the (La/Yb)N ratios of the two basins are significantly higher (from 0.67 to 1.18), which indicates an early diagenesis. The Ce/Ce* vs Pr/Pr* diagram shows that the observed Ce anomaly was not affected by diagenesis and more likely represents a proxy for redox conditions. The obtained results substantiate that the northern phosphorites were formed in more oxic environment with more pronounced negative Ce anomalies, whereas the southern phosphorites have lower Ce anomalies. Northern phosphorites are different from those from the south probably because the northern basin was more connected to an open sea as did the Sra Ouartan basin in northern Tunisia. These results have also been confirmed by statistical method studies, such as factorial discriminate analysis.

Résumé: Sited in Souk-Ahras, the Sidi El Hemissi region stands as part of the Tellian Atlas, where the Triassic formation tectonically outcrops under the Tellian nappes of the Maghrebide chain. Dubbed ‘ophites’, mafic rocks, mainly gabbros and dolerites are interbedded in *200
30 m lenticular body within the Triassic gypsum-rich formation. These rocks are composed of plagioclase, amphibole, pyroxene and scarce olivine crystals. Albitization represents the major alteration process, though chloritization, calcitization and epidotization of ferromagnesian minerals are also perceived. The geochemical observations prove to reveal that these mafic rocks exhibit medium- to low-Ti continental tholeiitic basalt affinity. They are enriched in LILE and LREE, as compared to HFSE and HREE, and display enriched-mid-ocean ridge basalt (E-MORB)-like incompatible element patterns in primitive mantlenormalized multi-element pattern. The weak Nb anomaly,possible interaction between an enriched mantle source-derived magma and lower crustal rocks. These chemical features display high similarities with those sited in the central Atlantic magmatic province (CAMP) of upper Triassic–lower Jurassic age. Hence, they turn out o be considered as highly linked to the western branch of the Alpine Tethys system, geologically and tectonically associated with the Central Atlantic Ocean opening. along with the medium- to low-Ti contents, suggests

Résumé: In contrast to the Cenomanian and Turonian, few researchers have studied the Coniacian interval. The Coniacian strata of the Tébessa Mountains in northern Algeria are predominantly marly facies that have been little studied. The present study is being carried out for the first time at Djebel Essen (west of Tébessa) to resolve the paleoenvironmental conditions. The identified taxa include 15 bivalve species, 3 gastropods, and one cephalopod, in addition to 4 irregular echinoids. Quantitative analyses of these macrofossils indicated the occurrence of three benthic Coniacian macrofaunal associations, which include: 1) Agelasina plenodonta, 2) Cucullaea, and 3) Oscillopha-Plicatula. Both Agelasina plenodonta and Cucullaea associations are dominated by infauna. However, Cucullaea Association contains only suspension-feeders, where deposit-feeders are completely absent, suggesting food scarcity (oligotrophy), which was result in the lowest diversity values. In contrast, epifaunal taxa were dominating the last association. All of the three associations are paucispecific. The general low diversity of the Coniacian associations in the study area, which is also indicated for other countries in North Africa, can be attributed to the retreat of the sea and the shrinking of the area of the shallower habitats. Probably, these associations were lived within restricted marginal marine environment. The absence of any marked indicator for the middle-upper Coniacian anoxic event (OAE-3) agrees with those from nearby sections and confirms a restricted extent of this event. The occurrence of many taxa with either regional or cosmopolitan affinity suggests episodic connection with the Tethyan Ocean. The results indicated that the marginal areas of the Tethys may have not influenced by the major Cretaceous climatic changes (e.g., global warming, anoxia, rising sea level, and ocean circulation).

Résumé: Dans le nord-est de l'Algérie, le Cénomanien se distingue par un patrimoine paléontologique riche et varié qui a mérité une attention particulière. Sa valorisation a débuté lors d'une première campagne en 2015 et se poursuit encore aujourd'hui, en apportant encore de nouveaux éléments importants. Ce patrimoine est localisé dans les monts de Bellezma-Batna, des Aurès et de Tébessa. Des collectes considérables ont été réalisées, avec plus de 6 000 spécimens regroupés en plus de 190 espèces, dont des bivalves, des gastéropodes, des ammonites, des échinodermes et des coraux. L’analyse des ammonites permet de discuter de l'importance de leur distribution stratigraphique et temporelle, et d’établir une zonation locale avec 11 biozones et 5 sous-biozones. Toutefois, l'extension stratigraphique des autres groupes omniprésents, à différents niveaux du Cénomanien et alignée sur celle des ammonites, permet encore de préciser le cadre biostratigraphique de cette période au NE d’Algérie. L'abondance, la biodiversité et la distribution des formes benthiques permettent de recenser des assemblages étroitement liés à la variation du niveau de la mer et permettent ainsi la reconstitution paléoenvironnementale. Au Cénomanien inférieur, un environnement profond avec un substrat vaseux situé dans la partie distale de la plate-forme a favorisé la richesse et la diversification en spécimens. Au cours du Cénomanien moyen, un environnement marin peu profond s'est établi avec des courants de faible énergie, des eaux chaudes et un taux de sédimentation élevé. Au Cénomanien supérieur, un milieu sublittoral profond riche en macro-benthiques qui devient moins profond vers la fin de cette période. Enfin, le Cénomanien terminal correspond à un environnement subrécifal peu profond, caractérisé par la rareté et la faible biodiversité. La large répartition paléobiogéographique de ces macro-invertébrés au cours du Cénomanien témoigne d'une affinité téthysienne.