Middle Cenomanian Research Articles

Taxonomy and taphonomy of Cenomanian (Upper Cretaceous) nautilids from Annopol, Poland

Abstract A nautilid faunule of seven specimens, comprising Eutrephoceras bouchardianum (d’Orbigny, 1840), Cymatoceras deslongchampsianum (d’Orbigny, 1840), and Cymatoceras tourtiae (Schlüter, 1876) is described from a condensed middle Cenomanian interval at Annopol, Poland. C. tourtiae is recorded for the first time in Poland. The studied material consists of reworked phosphatised internal moulds of phragmocones, which may be of early or middle Cenomanian age, given the stratigraphic range of the associated ammonites. The nautilid moulds vary in inferred mode of infilling, and in intensity of abrasion, bioerosion and mineralisation. The sediment entered the phragmocones in two ways: 1) through punctures in the shell, the result of bioerosion or mechanical damage; 2) through siphonal openings by intracameral currents. In contrast to the fossil moulds from the Albian phosphorites of Annopol, which originated via direct precipitation of apatite around and/or inside fossils, the present nautilid moulds seem to have originated through secondary phosphatisation of the initially calcareous moulds. Diversity of taphonomic signatures in nautilid material from the middle Cenomanian interval at Annopol is compatible with the complex, multievent depositional scenario proposed for this level.

Inflorescences of Mauldinia sp. (Lauraceae) and associated fruits from the Cenomanian of Languedoc Roussillon, France

Inflorescences of Mauldinia (Lauraceae) are described from the middle Cenomanian Pauletian facies of Gard, Languedoc-Roussillon, south-eastern France. This is the first record of the genus from this part of Europe. Mauldinia sp. is described based on peduncles and lateral units. Isolated, slender peduncles show spirally arranged scars or rarely attached lateral units. Isolated lateral units consist of cladode-like structures showing up to seven flower/fruit scars. Some isolated fruits were found associated with peduncles and lateral units. Fruits are ovoid fruits contain a single, elongated seed. The pericarp consists of epicarp, mesocarp and endocarp. The seed consists of two cotyledons containing well-developed reserve cells. Mauldinia sp. from Gard differs from known Mauldinia species by having longer internodes along the peduncle and by the shape of the lateral units. Sedimentological and palaeontological evidence suggests that Mauldinia sp. from Gard grew in a protected, littoral environment with limited marine influence. This report provides new information to the relatively poorly known Cretaceous record of angiosperms in France. The occurrence of Mauldinia in the lower Upper Cretaceous of Gard corroborates the widespread occurrence of the genus in marginal littoral environments during the mid-Cretaceous.

First North American occurrence of the toothed pteranodontoid pterosaur Cimoliopterus

ABSTRACTA new pterosaur species, Cimoliopterus dunni, sp. nov., is described based on a partial rostrum from the upper Cenomanian Britton Formation in the Eagle Ford Group of north-central Texas. The holotype preserves alveoli for a minimum of 26 upper teeth and bears a thin premaxillary crest that begins above the fourth pair of alveoli. The rostrum, characterized by a slight lateral flare, lacks the pronounced lateral expansion found in ornithocheirids and anhanguerids. The tip of the snout is small and blunt, and the anterior face of the rostrum is oriented posteroventrally, forming an approximately 45° angle with the anterior portion of the palate. The anteroventrally oriented first pair of alveoli is directed more ventrally than anteriorly. Phylogenetic analysis suggests that Cimoliopterus dunni and Cimoliopterus cuvieri, from the Cenomanian Grey Chalk Subgroup in Kent, England, are basal pteranodontoids that are closely related to Aetodactylus halli from the middle Cenomanian Tarrant Formation of north Texas. Cimoliopterus dunni marks only the second known occurrence of Cimoliopterus, extending its geographic range from Europe to North America. In conjunction with Coloborhynchus wadleighi from the upper Albian Pawpaw Formation, Cimoliopterus dunni provides unambiguous evidence of biogeographic linkages between the pterosaur faunas of North America and Europe in the middle Cretaceous.http://zoobank.org/urn:lsid:zoobank.org:pub:50FDA47D-0E2D-4B6E-9A18-8F04F814CE62SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Myers, T. S. 2015. First North American occurrence of the toothed pteranodontoid pterosaur Cimoliopterus. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1014904.

Upper Albian-Turonian foraminifers and radiolarians from the Kelevudag section, northeastern Azerbaijan

New data on planktonic and benthic foraminifers and radiolarians derived from the upper Albian-Turonian sediments of the Kelevudag section, northeastern Azerbaijan, are reported. Two planktonic foraminiferal biostratigraphic units are recognized, namely, the Thalmanninella deeckei Beds (uppermost lower–lowermost middle Cenomanian, top of the lower part of the Kemishdag Formation) and Dicarinella hagni Beds (lower Turonian, top of the upper part of the Kemishdag Formation). Two units, the Pseudovalvulineria cenomanica–Berthelina berthelini Beds (middle–upper Cenomanian, top of the lower part of the Kemishdag Formation) and Lingulogavelinella globosa Beds (upper Cenomanian–lower Turonian, top of the upper part of the Kemishdag Formation), are distinguished by benthic foraminifers. On the basis of the radiolarian studies, the following units are defined: the Dorypyle — anisa–Pseudodictyomitra languida Beds (upper Albian, upper part of the Kyulyuli Formation), Patellula spica–Crolanium triangulare Beds (lower Cenomanian, base of the lower part of the Kemishdag Formation), Pseudoaulophacus lenticulatus–Thanarla gracilis Beds (middle Cenomanian, top of the lower part of the Kemishdag Formation), and the Orbiculiforma quadrata–Pseudodictyomitra pseudomacrocephala Beds (uppermost upper Turonian, lower part of the Kemchi Formation). The age estimates available from foraminifers and radiolarians do not contradict each other. The time of accumulation of the Kemishdag Formation was previously considered within only the Cenomanian. According to the new available foraminiferal data, the range of the Kemishdag Formation is widened and it is believed to correspond to the Cenomanian–lower Turonian. On the basis of foraminiferal and radiolarian studies, the stratigraphic position of the lower boundary of the Kemchi Formation is determined within the Turonian and the Turonian–Coniacian boundary is defined in the lower part of the Kemchi Formation.

Origin and phylogeny of the Cretaceous thoracican cirripede family Stramentidae

A cladistic analysis of basal scalpellomorph cirripedes was undertaken in order to identify the phylogenetic position of the Stramentidae. This yielded a well-supported tree, in which the family is positioned crownwards of Archaeolepas, but basal to the families Scalpellidae and Zeugmatolepadidae. A new genus, Loriolepas, is described to accommodate some species previously referred to Archaeolepas. Basal scalpellomorphs display a remarkable change in shell mineralogy from calcium phosphate to calcium carbonate (Eolepas to Archaeolepas); the latter group is identified as a monophyletic clade, the Thoracicalcarea nov. A revised taxonomy of the predominantly Late Cretaceous cirripede family Stramentidae is presented. Stramentidae are subdivided into two subfamilies, Loriculinae subfam. nov., and Stramentinae, based on characters of tergum, carinolatus and peduncular plates. The former subfamily includes Loriculina Dames, 1885, Metaloriculina gen. nov. and, doubtfully, Blastolepas Drushchits & Zevina, 1969, and three new species are described, Loriculina ifrimae sp. nov., Metaloriculina stramentioides sp. nov and Metaloriculina norvicensis sp. nov. The Stramentinae include Leweslepas gen. nov., Stramentum Logan, 1897 and Parastramentum gen. nov. New species are Leweslepas hattini sp. nov, L. hauschkei sp. nov, L. wrightorum sp. nov, Parastramentum albertaensis sp. nov, P. brydonei sp. nov, P. peakei sp. nov, Stramentum alekseevi sp. nov and S. praecursor sp. nov. Cladistic analysis of the Stramentidae, based on 25 characters, supports the monophyly of the family, but relationships between subfamilies and genera are poorly resolved. However, in north-west Europe there is an evolutionary morphocline, stratigraphically calibrated, from the early Cenomanian Leweslepas hauschkei gen. et sp. nov. through the middle Cenomanian Stramentum praecursor sp. nov. to the late Cenomanian–Turonian S. pulchellum. A split from this lineage is found in the Western Interior Basin of North America, and the early Turonian S. canadensis gave rise to the middle Turonian S. elegans, which lived epibenthically. Stramentum elegans gave rise to Parastramentum gen. nov.http://zoobank.org/urn:lsid:zoobank.org:pub:E01B7F39-6C1B-4AF3-B79A-E2D5972D3E28

Middle Cenomanian (Late Cretaceous) molluscs of the Shaftesbury Formation, Birch Mountains, northeastern Alberta, Canada

Historical Resources Impact Assessment and Mitigation studies have documented a new middle Cenomanian invertebrate fauna from the Shaftesbury Formation in the Birch Mountains, northwest of Fort McMurray, in northeastern Alberta, Canada. Although older portions (Albian) of the Shaftesbury Formation in Alberta and British Columbia have yielded invertebrate fossils, this is the first fauna of middle Cenomanian age known for the unit. The fauna includes the ammonites Acanthoceras wyomingense and Borissjakoceras orbiculatum, the inoceramid bivalves Inoceramus dunveganensis and Inoceramus prefragilis stephensoni, and the gastropod Pirsila tensa. The occurrence of the late middle Cenomanian zonal fossil A. wyomingense allows correlation between the middle “Fish Scales Formation” of the Shaftesbury Formation and the lower part of the Labiche Formation of Alberta, and with five units farther to the south in the United States, namely the Greenhorn Limestone, Lincoln Formation, and Graneros Shale of Kansas, the Frontier Formation of Wyoming, and the Belle Fourche Shale of Montana.

The uppermost Albian–lower Cenomanian Bielba Formation of the type-area (Cantabria, northern Spain): facies, biostratigraphy, and benthic Foraminifera

The lithofacies, microfacies, depositional sequences, and benthic Foraminifera of the uppermost Albian–lower Cenomanian Bielba Formation in its type-area in northern Cantabria, Spain, consisting of a lower siliciclastic member and an upper Cobreces Member, have been investigated. The investigated section constitutes a hypostratotype for the Bielba Formation, and the lower siliciclastic member is here formally defined as the Somocuevas Member. The obtained data are framed in the major global paleoenvironmental and paleoceanographic changes that occurred during the Albian–Cenomanian transition. Eleven lithofacies types have been identified from facies analysis and vertical log characterization. These lithofacies accumulated in various depositional settings such as storm, wave, and tidal influenced delta front and shoreface, shallow-water carbonate ramp, and offshore marine environments. Within an overall transgressive trend, the succession of the Bielba Formation comprises two depositional transgressive–regressive sequences corresponding to the Somocuevas and Cobreces Members, bounded by a major relative sea-level fall at the end of the Albian. The sea-level fall was followed by a rapid marine transgression and shifting from siliciclastic-dominated deposition of the Somocuevas Member to carbonate-dominated deposition of the Cobreces Member. The microfauna of the Cobreces Member is characterized by omnipresent orbitolinids, trocholinids, and a variety of other mostly small-sized foraminifera that so far have not attracted much attention. Among them, taxa with biostratigraphic importance and taxonomic–phylogenetic importance can yet be found. The benthic Foraminifera are associated with calcareous green algae (dasycladaleans, udoteaceans) and occur in calcarenites of poorly diversified microfacies containing variable amounts of siliciclastics. The microfauna closely compares to that of the overlying late early to middle Cenomanian Altamira Formation.

Large predatory marine reptiles from the Albian–Cenomanian of Annopol, Poland

AbstractDuring the Early–Late Cretaceous transition, marine ecosystems in Eurasia hosted a diverse set of large predatory reptiles that occupied various niches. However, most of our current knowledge of these animals is restricted to a small number of bonebed-like deposits. Little is known of the geographical and temporal extent of such associations. The middle Albian – middle Cenomanian phosphorite-bearing succession exposed at Annopol, Poland produces numerous ichthyosaurian and plesiosaurian fossils. These are mostly isolated skeletal elements (e.g. teeth, vertebrae), but disarticulated partial skeletons and an articulated, subvertically embedded ichthyosaur skull are also available. The following taxa are identified: ‘Platypterygius’ sp., cf. Ophthalmosaurinae, Ichthyosauria indet.,Polyptychodon interruptus, Pliosauridae indet., Elasmosauridae indet. and Plesiosauria indet. The large-sized ichthyosaur ‘Platypterygius’ and the pliosauridPolyptychodon interruptuspredominate within the upper Albian – middle Cenomanian deposits. The Annopol record, combined with data from England, France and western Russia, suggests that ‘Platypterygius’ andPolyptychodon interruptusformed a long-term, stable ecological sympatry in marine ecosystems of the European archipelago, at least during the Albian – middle Cenomanian. In addition, the marine reptile assemblage from Annopol is distinct from other Eurasian ecosystems in containing also elasmosaurids in its Albian portion.

Fossocytheridea Swain & Brown and Perissocytheridea Stephenson (Ostracoda): insights into paleosalinity gradients of Late Cretaceous deposits from Brazil and Portugal

Fossocytheridea Swain & Brown and Perissocytheridea Stephenson are genera characteristic of brackish water environments. In 51 samples from the Santonian-Campanian, from the well 9-MO-13-RN, Potiguar Basin, Brazil, Fossocytheridea potiguarensis Piovesan, Cabral & Colin, Fossocytheridea POT 1 Piovesan, Cabral & Colin and Perissocytheridea jandairensis Piovesan, Cabral & Colin have been identified. In the Sao Joao das Lampas section (middle Cenomanian), Lusitanian Basin, Portugal, 25 samples were studied and Fossocytheridea merlensis (Babinot & Colin) and Perissocytheridea estribeirensis Andreu have been recognized. The distributional pattern of the Fossocytheridea-Perissocytheridea assemblage, combined with analysis of the abundance and diversity of marine ostracodes, suggests that in the Late Cretaceous Fossocytheridea and Perissocytheridea were euryhaline genera, and that the tolerance to salinity gradients is related to the ecology of each species and not strictly to that of the genus.

Environmental Conditions in a Carpathian Deep Sea Basin During the Period Preceding Oceanic Anoxic Event 2 - A Case Study from the Skole Nappe

Abstract Hemipelagic green clayey shales and thin muddy turbidites accumulated in a deep sea environment below the CCD in the Skole Basin, a part of the Outer Carpathian realm, during the Middle Cenomanian. The hemipelagites contain numerous radiolarians, associated with deep-water agglutinated foraminifera. These sediments accumulated under mesotrophic conditions with limited oxygen concentration. Short-term periodic anoxia also occurred during that time. Muddy turbidity currents caused deposition of siliciclastic and biogenic material, including calcareous foramini-fers and numerous sponge spicules. The preservation and diversity of the spicules suggests that they originate from disarticulation of moderately diversified sponge assemblages, which lived predominantly in the neritic-bathyal zone. Analyses of radiolarian ecological groups and pellets reflect the water column properties during the sedimentation of green shales. At that time, surface and also intermediate waters were oxygenated enough and sufficiently rich in nutri-ents to enable plankton production. Numerous, uncompacted pellets with nearly pristine radiolarian skeletons inside show that pelletization was the main factor of radiolarian flux into the deep basin floor. Partly dissolved skeletons indicate that waters in the Skole Basin were undersaturated in relation to silica content. Oxygen content might have been depleted in the deeper part of the water column causing periodic anoxic conditions which prevent rapid bacterial degra-dation of the pellets during their fall to the sea floor.

Paleogeographic Evolution of the Eastern Edge of the Douala Basin from Early Cenomanian to Turonian

In order to trace the paleogeographic evolution of the eastern edge of the Douala basin from lower Cenomanian to Turonian, sedimentological and palynostratigraphic analyses have been carried out. The studied formations are about 80 m thick and are made up of continental detrital facies, which are coarse at the bottom and progressively become finer towards the top of the sequence. These rocks are overlain by marine deposits, composed of thin layers of black clay and bioclastic limestone. These formations were deposited during two sedimentation phases, namely, the continental deposit phase, which is composed of conglomerates infilling the basin, followed by the transgressive deposits associated with deepening of the basin environment. Sequence analysis of these different facies, indicates that the turbidites are composed of small sequences that constitute a transgressive megastructure. This succession was deposited during a megatransgressive phase that continued until the final stage of the basin infilling. According to palynologic data, strata were deposits from the early Cenomanian at the bottom to the Turonian towards the top. The depositional environment changed over time, passing from (1) a narrow and steep-sided tectonic basin, during the early to middle Cenomanian, followed by (2) a lacustrine to palustrine basin with marine incursions, as a result of the E-W distensive movements between the South American and Northwest African blocks in the middle and late Cenomanian, and (3) to a confined and shallow sea during the Turonian. The climate remained warm and became progressively humid towards the end of the Cretaceous. The nature of these environments is related to the dynamics of the opening of the South Atlantic Ocean.

Sea level changes in the upper Aptian-lower/middle(?) Turonian sequence of Cauvery Basin, India – An ichnological perspective

Cauvery Basin, a pericratonic rift basin along the Eastern Continental Margin of India, evolved during the breakup of the Eastern Gondwanaland. It exposes both syn-rift and later post-rift passive margin deposits ranging from Barremian to Miocene. The Karai Formation, upper Aptian-lower/middle (?) Turonian represents the oldest passive margin in the Cauvery Basin. It is bounded at both contacts by major sequence boundaries viz. the break-up unconformity and the Turonian tilt event. The present communication deals with the ichnology of the Karai Formation and its integration with sedimentary facies and biostratigraphy to interpret the sea level changes during deposition. A traverse between the villages Karai and Kulakkalnattam was studied in detail for this purpose. Based on the lithological position, characters and internal grain size trends, the Karai Formation is sub-divided into four informal lithologic units; the lower three units, constitute a lithostratigraphic unit known in literature as the Gypsiferous Clay Member, while the uppermost, corresponds to the Sandy Clay Member. At the base, clays of the Karai Formation unconformably onlap onto the Precambrian basement or the fluvial syn-rift deposits across the break-up unconformity. Upper Aptian to middle Cenomanian, units I and II showing the distal Cruziana ichnofacies, deepening of the basin and a retrogradational stacking pattern represent a transgressive system tract (TST). This long phase of transgression is attributed to continuous accommodation created by the post-breakup thermal subsidence. The upper part of unit II (middle Cenomanian) shows condensation, with its top representing the maximum flooding surface (MFS). Upper Cenomanian to lower/middle (?) Turonian, units III and IV characterised by a shift from the distal Cruziana to the Skolithos ichnofacies, an initial aggradational and later deltaic, progradational stacking pattern resulting from a fall in the relative sea level and filling up of accommodation space represent the highstand system tract (HST). A further fall in the relative sea level led to the exposure, incision and erosion of the Karai Formation over which the younger transgressive sequence of the Trichinopoly Group was deposited with an angular unconformity.

A fossil ray spider (Araneae: Theridiosomatidae) in Cretaceous amber from Vendée, France

A new species of fossil ray spider, Baalzebub? mesozoicum n. sp. (Araneae: Theridiosomatidae), is described from Mesozoic amber from the Cretaceous (Middle Cenomanian to Early Santonian) deposits of La Garnache, Vendee, NW France. The palpal structures, especially the highly sclerotized claw-shaped retrolateral ‘paracymbium’ originating as an outgrowth of the cymbium basally and the basal cymbial lamella, are considered sufficient to make a tentative placement of the new fossil species in the extant genus Baalzebub Coddington, 1986.

Insights from exceptionally preserved Cenomanian trocholinids (benthic foraminifera) of northern Cantabria, Spain

Rich and diverse trocholinid assemblages have been recorded from the lower to middle Cenomanian Altamira and Bielba formations of the Bascocantabrian Basin, northern Spain. They occur in bioclastic for-algal grainstones and near-reefal rudstones referred to platform margin environments. This material, partially impregnated by iron-rich solutions, is unusually well-preserved and offers the unique opportunity to carry out a detailed study of the last diversified assemblages of the aragonitic foraminiferal order Involutinida. It notably allows (1) describing one new subfamily (Coscinoconinae n. subfam.), two new genera (Hensonipapillus n. gen. and Paracoscinoconus n. gen.), and five new species (Coscinoconus discoideus n. sp., Frentzenella pygmaea n. sp., Hensonipapillus cantabricus n. sp., H. altamirensis n. gen., n. sp., and Paracoscinoconus semiinvolutus n. sp.); (2) clarifying the relationship between the umbilical canal system and the laminar deposits in Late Jurassic–Cretaceous coscinoconins; (3) emending and providing new combinations for “Trocholina” lenticularis Henson, 1947 “T.” minima Henson, 1947 and “T.” burlini Gorbatchik, 1959 which have been repeatedly misidentified in the literature; (4) discussing the epibenthic mode of life of trocholinids; and (5) proposing an explanation for their extinction at the Cenomanian–Turonian boundary.

The stratigraphic setting of cretaceous volcanic rocks in Crimea and in the North Caucasus

The ages of volcanic activity in the Crimea and North Caucasus are reported in this paper. The age estimation of the described ranges is based on the results of micropaleontological analysis (planktonic Foraminifera) with account for the data on other groups, mostly Ammonites and Inoceramids. Volcanic rocks are related to the Upper Albian (Thalmanninella appenninica Zone), Lower Cenomanian (Thalmanninella globotruncanoides Zone) deposits, boundary deposits of the Lower and Middle Cenomanian (Thalmanninella deeckey Zone), and Middle-Upper Cenomanian (Rotalipora cushmani Zone). Volcanic activity was found for the Campanian Stage (Globotruncanita elevate and Globotruncana ventricosa) as well.

Biostratigraphy of Cenomanian succession in Zagros area (southwest of Iran)

This study is focused on biozonation and biostratigraphic limits of two selected stratigraphic sections of the Sarvak Formation (Cenomanian) which are nominated Bavan and Kharameh (southwestern folded Zagros Mountain Ranges of Iran). Based on the vertical distribution of benthic and planktonic foraminifers, one biozone in Bavan area and three biozones in Kherameh stratigraphic section have established which are: Chrysalidina gradata-Cuneolina pavonia Assemblage zone (Upper Cenomanian) in Bavan section, and established biozones in Kherameh stratigraphic section from the base to the top consist of: 1) Praealveolina iberica-Praealveolina pennensis Assemblage zone (Lower Cenomanian), 2) Nezzazata conica-Nezzazata simplex Assemblage zone (Middle Cenomanian), 3) Calcisphaerula innominata-Heterohelix reussi-Heterohelix moremani Assemblage zone (Upper Cenomanian). New micropaleontologic data confirms well diversified and expanded of imperforate foraminifera in both studied stratigraphic sections. Well developed planktonic foraminifers in Kherameh stratigraphic column reflect transgression of sea-level rise during Upper Cenomanian.

SimbirskiasaurusandPervushovisaurusreassessed: implications for the taxonomy and cranial osteology of Cretaceous platypterygiine ichthyosaurs

The ichthyosaur fossil record is interspersed by several hiatuses, notably during the Cretaceous. This hampers our understanding of the evolution and extinction of this group of marine reptiles during the last 50 million years of its history. Several Cretaceous ichthyosaur taxa named in the past have subsequently been dismissed and referred to the highly inclusive taxon Platypterygius, a trend that has created the impression of low Cretaceous ichthyosaur diversity. Here, we describe the cranial osteology, reassess the stratigraphic age, and evaluate the taxonomy and phylogenetic relationships of two Cretaceous ichthyosaurs from western Russia: Simbirskiasaurus birjukovi from the early Barremian and Pervushovisaurus bannovkensis from the middle Cenomanian, both formerly regarded as nomina dubia, and allocated to Platypterygius sp. and Platypterygius campylodon, respectively. We show that Simbirskiasaurus birjukovi and Pervushovisaurus bannovkensis are valid platypterygiine ophthalmosaurids, notably characterized by a peculiar narial aperture. The cranial anatomy and phylogenetic relationships of these taxa illuminate the evolution of narial aperture anatomy in Cretaceous ichthyosaurs, clarify the phylogenetic relationships among platypterygiines, and provide further arguments for a thorough revision of Platypterygius.

First Cenomanian record of insects in the Southern Hemisphere, with Perforissidae (Fulgoroidea) and Cupedidae (Coleoptera) from Southern Patagonia, Argentina

The discovery of the southernmost world record (49.5°S) of a Late Cretaceous insect fauna and plant-insect interactions is reported herein. The new locality is from the middle Cenomanian lacustrine deposits of the Mata Amarilla Formation belonging to the Austral foreland Basin, southwest Patagonia, Argentina. A first trip to the locality yielded few specimens of Coleoptera, among them an Archostemata: Cupedidae, and also a tiny specimen of Fulgoroidea: Perforissidae represented by Aonikenkissus zamunerae gen. et sp. nov. The Perforissidae were previously recorded from the Berriasian (?)-Barremian, Aptian, Albian, Turonian and Santonian in the Northern Hemisphere. The new species represents the first record of Perforissidae for South America and for the whole Southern Hemisphere. The new record suggests that the Perforissidae had a broader biogeographical distribution, and seem to have been cosmopolitan in the mid-Cretaceous. The Cupedidae reported herein is the first record for the Cenomanian and the first record of the genus Zygadenia in South America. Insect traces found in the same strata are made in an angiosperm palmatilobed leaf and correspond to a piercing and sucking type of damage. This type of damage is compared to recent stipples and to isolated piercings.

An early Late Cretaceous (Cenomanian) sturgeon (Acipenseriformes) from the Dunvegan Formation, northwestern Alberta, Canada

A recent survey of the middle Cenomanian Dunvegan Formation along the Peace River, Alberta, has yielded a partial skull of a large acipenseriform fish. The fossil was from an animal approximately 5 m in length, based on comparisons with living relatives. Though incomplete, this represents an important record of mid-Cretaceous fish from northern North America, as formations of this age are virtually unexplored in northern regions. This fossil is the oldest acipenserid from North America, and one of the most northerly known.

SEQUENCE STRATIGRAPHIC ANALYSIS OF THE MID‐CRETACEOUS MISHRIF FORMATION, SOUTHERN MESOPOTAMIAN BASIN, IRAQ

The middle Cenomanian – early Turonian Mishrif Formation, a major carbonate reservoir unit in southern Iraq, was studied using cuttings and core samples and wireline logs (gamma‐ray, density and sonic) from 66 wells at 15 oilfields. Depositional facies ranging from deep marine to tidal flat were recorded. Microfacies interpretations together with wireline log interpretations show that the formation is composed of transgressive and regressive hemicycles. The regressive hemicycles are interpreted to indicate the progradation of rudist lithosomes (highstand systems tract deposits) towards distal basinal locations such as the Kumait, Luhais and Abu Amood oilfield areas. Transgressive hemicycles (transgressive systems tract deposits) represent flooding of the shallow carbonate platform and are recorded in oilfields such as Amara, Halfaya and Zubair.A sequence stratigraphic framework has been constructed for the Mishrif Formation based on correlation of the transgressive and regressive hemicycles which are separated by maximum flooding surfaces. Three third‐order sequences are identified which show lateral and vertical facies variations depending on relative sea‐level changes. Sequence boundaries are characterized by karstic, exposure and drowning features. Middle Cenomanian – Turonian eustatic sea‐level changes together with regional‐scale tectonic deformation of the Arabian Plate controlled the availability of accommodation space and therefore the depositional profile during development of each sequence. Both of these factors controlled the maximum flooding surfaces and sequence boundaries which have been identified.The sequence stratigraphic key surfaces presented in this study represent typical candidate horizons or datum surfaces for future seismic or resevoir modelling studies. Also, lateral facies variations in each transgressive‐regressive sequence and associated carbonate bodies (i.e. prograding shelf margin, forced regressive wedge) may form important stratigraphic traps in the Mesopotamian Basin.