Cenomanian-Turonian rudists from Western Sinai, Egypt: Systematic paleontology and paleoecology

Geobios 44 (2011) 409–433

Original article

Cenomanian-Turonian rudists from Western Sinai, Egypt: Systematic paleontology and paleoecology§ Rudistes du Cénomanien-Turonien du Sinaï Occidental : paléontologie systématique et paléoécologie Mohamed S. Zakhera Department of Geology, Aswan Faculty of Science, South Valley University, Aswan, 81528 Egypt Received 4 January 2010; accepted 24 October 2010 Available online 28 April 2011

Abstract The Cenomanian-Turonian sequence is well exposed in western central Sinai and contains a considerable number of rudist species. The identified rudists belong to Radiolitidae, Hippuritidae and Requieniidae. Fifteen species are described, belonging to ten genera: Requienia, Toucasia, Apricardia, Radiolites, Eoradiolites, Praeradiolites, Sphaerulites, Sauvagesia, Hippurites, and Vaccinites. Eleven species are reported in the Cenomanian and four species in the Turonian. Within the Cenomanian, two new species are described: Requienia tortuosi and Eoradiolites lenisexternus. The genus Requienia and the species Apricardia carentonenis d’Orbigny, Eoradiolites syriacus (Conrad), Sphaerulites agariciformis Delamétherie, Sphaerulites depressus Blanckenhorn and Vaccinites cf. grossouvrei (Douvillé) are reported for the first time from Egypt. The Cenomanian and Turonian rudists in the western Sinai show either elevator or clinger morphotypes, with the predominance of the former type; recumbent mode of life is rarely represented by some Requieniidae. The elevators are of isolated and clustered occurrences and more represented in the Cenomanian sequence. Rudists of the study area are mainly of parautochthonous fabrics with low to dense packing. Autochthonous fabrics are also achieved by some species, mainly in the Turonian. The disappearance of rudists from the middle part of the sequence and above the Cenomanian/Turonian boundary is due to a deeper setting that resulted from sea-level rise or seafloor subsidence (shelf drowning). The occurrence of rudists with oysters and other benthic fossils in the siliciclastic and carbonate sediments of the Cenomanian and Turonian sedimentary rocks in the Sinai indicate that the sequence was deposited on a broad, shallow shelf. Although the first marine transgression invaded the central Sinai in the late Cenomanian, transgressive deepening conditions continued until the Turonian. The rudists of central Sinai are of Tethyan affinity with significant relation with North Africa, the Middle East, and Southern Europe. # 2011 Published by Elsevier Masson SAS. Keywords: Cenomanian; Turonian; Rudists; Systematic; Paleoecology; Egypt

Résumé Une séquence cénomano-turonienne particulièrement riche en rudistes est bien exposée dans la partie occidentale du Sinaï central. Les rudistes identifiés appartiennent aux Radiolitidae, Hippuritidae et Requieniidae. Quinze espèces (onze cénomaniennes et quatre turoniennes) sont décrites, appartenant à dix genres : Requienia, Toucasia, Apricardia, Radiolites, Eoradiolites, Praeradiolites, Sphaerulites, Sauvagesia, Hippurites et Vaccinites. Deux nouvelles espèces cénomaniennes sont décrites : Requienia tortuosi et Eoradiolites lenisexternus. Le genre Requienia et les espèces Apricardia carentonenis d’Orbigny, Eoradiolites syriacus (Conrad), Sphaerulites agariciformis Delamétherie, Sphaerulites depressus Blanckenhorn et Vaccinites cf. grossouvrei (Douvillé) sont identifiés pour la première fois en Égypte. Les rudistes du Cénomanien et du Turonien du Sinaï occidental présentent des morphotypes dressés ou fixés-cramponnés, les premiers prédominant ; le mode de vie couché n’est représenté que par quelques rares Requieniidae. Les formes dressées sont trouvées isolées ou groupées ; elles sont mieux représentées dans la séquence cénomanienne. Les rudistes de la zone étudiée présentent essentiellement des fabriques parautochtones de densités faibles à élevées. Des fabriques autochtones sont également réalisées par quelques espèces, principalement durant le Turonien. La disparition des rudistes au milieu de la séquence et au-dessus de la limite Cénomanien-Turonien est due à un approfondissement résultant d’une élévation du niveau marin ou de la subsidence (ennoiement de la plateforme). La présence de rudistes aux côtés d’huitres et d’autres fossiles d’organismes benthiques dans les sédiments

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Corresponding editor: Fabienne Giraud. E-mail address: [email protected].

0016-6995/$ – see front matter # 2011 Published by Elsevier Masson SAS. doi:10.1016/j.geobios.2010.10.004

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siliciclastiques et carbonatés des dépôts sédimentaires cénomaniens et turoniens du Sinaï indiquent que la séquence s’est formée sur une plateforme étendue et peu profonde. Bien que la première transgression marine ait envahie le Sinaï central durant le Cénomanien supérieur, l’approfondissement transgressif a perduré jusqu’au Turonien. Les rudistes du Sinaï central sont d’affinité téthysienne, montrant des relations significatives avec l’Afrique du Nord, le Moyen Orient et l’Europe méridionale. # 2011 Publié par Elsevier Masson SAS. Mots clés : Cénomanien ; Turonien ; Rudistes ; Systématique ; Paléoécologie ; Égypte

1. Introduction Rudists are one of the fossil groups that demised at the end of the Cretaceous Period. They belong to bivalves but had bizarre growth form. Rudists inhabited the tropical carbonate platforms since the late Jurassic (Masse and Philip, 1981; Scott, 1988; Ross and Skelton, 1993; Swinburne and Masse, 1995; Mitchell, 1999; Sanders and Pons, 1999; Steuber and Löser, 2000; Özer et al., 2009). They became abundant in Cretaceous tropical deposits. They are therefore important in studying ancient tropical environments and their peculiar form also makes them an interesting subject of morphologic and systematic study. In Egypt, systematic studies on rudists are generally lacking. Rudists of the Abu Roach (Egyptian Western Desert) were treated by some authors (Fourtau, 1900, 1903; Dacqué, 1903; Douvillé, 1910, 1913; Hamza, 1993; De Castro and Sirna, 1996; El-Sabbagh and El-Hedeny, 2003; El-Hedeny, 2007; Abdel Gawad et al., 2008). Some rudists from the northern Eastern Desert were reported by Douvillé (1913), Klinghardt (1929) and El-Hedeny and El-Sabbagh (2005). Since the studies by Douvillé (1910, 1913, 1915), rudists in Sinai have received attention of some authors (Parnes, 1987; Kora and Hamama, 1987; Kuss, 1992; Steuber et al., 1999; Steuber and Bachmann, 2002; Abdel Gawad et al., 2004a, 2004b; Bauer et al., 2004; Aly et al., 2005; Zakhera, 2005, 2008; Saber et al., 2009). Most of these studies dealt only with reporting rudist occurrences. No comprehensive paleoecological and biostratigraphical studies [(Fig._paleontological, 1)TD$FIG]

have been conducted on the rudist of western Sinai. The Cenomanian through Turonian sequence is well exposed in western Sinai and contains a considerable number of rudist species. This paper aims to report rudist bivalves from new localities in western Sinai (Fig. 1), and to study their systematic classification and paleoecological conditions. In addition, I intend to shed some light on the stratigraphy, environmental setting of the containing sediments and paleobiogeographic affiliation of the studied rudists. 2. Stratigraphy, distribution and age calibration of the reported rudists The Cenomanian-Turonian sequence in Sinai shows lateral variation in lithofacies, biofacies and thickness due to local tectonics and sea level changes (Kuss, 1989). The investigated area lies at the western part of central Sinai. The central and southern Sinai lie within the ‘‘Stable Shelf’’ of Said (1962), which is characterised by less tectonic stresses and flat laying strata. The Cenomanian strata are mainly made up of carbonate rocks in north Sinai; they have greater clastics in south Sinai (Kerdany and Cherif, 1990). The Turonian beds are composed mainly of carbonate throughout Sinai. During that time, Sinai represents a passive margin of the southern Tethys.The stratigraphic sequence from which the rudists are obtained from Wadi El Siq, Wadi El Bagha and Gebel Musabaa Salama,

Fig. 1. Location map, showing the rudist localities in western Sinai, Egypt.

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is classified into the Raha Formation of calcareous clastic lithology, the Abu Qada Formation of clastics and more carbonate lithology, and the Wata Formation of carbonate lithology (Figs. 2 and 3). In Wadi El Siq and Wadi El Bagha sections (Fig. 2), three rudist levels can be distinguished from the late Cenomanian Neolobites vibrayeanus Zone (Zakhera and Kassab, 2002) of the Raha Formation, as follows (from bottom to top):  level A (calcareous mudstone): Sphareulites depressus Blanckenhorn, Radiolites lusitanicus (Bayle), and Eoradiolites liratus (Conrad);

[(Fig._ 2)TD$FIG]

Fig. 2. Lithostratigraphy, ammonite zones and rudist range chart of Wadi El Bagha and Wadi El Siq sections. Ps. flex. = Pseudaspidoceras flexuosum; Vas. pro. = Vascoceras proprium.

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 level B (silty marl): Sphareulites depressus Blanckenhorn and Sphaerulites agariciformis Delamétherie;  level C (calcareous mudstone): Praeradiolites biskraensis (Coquand) and Sphaerulites agariciformis Delamétherie. These rudists are associated with some other bivalves and gastropods. The Turonian rudists are reported from the ammonite Choffaticeras sege Zone within the upper part of the Abu Qada Formation, including Vaccinites cf. grossouvrei (Douvillé), Hippurites resectus Defrance and Sauvagesia sharpei (Bayle), associated with few other bivalve species. The upper part of the late Cenomanian

[(Fig._ 3)TD$FIG]

Fig. 3. Lithostratigraphy, ammonite zones and rudist range chart of Gebel Musabaa Salama. Pseud. flexu. = Pseudaspidoceras flexuosum; Vas. proprium = Vascoceras proprium.

[(Fig._ 4)TD$FIG] 412

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and the early Turonian sequence is devoid of any rudist bivalves. In the Gebel Musabaa Salama section (Fig. 3), the lower member of the Raha Formation is devoid of rudists but it contains abundant oyster banks of Ilymatogyra Africana (Lamarck) and Ceratostreon flabellatum (Goldfuss). The Cenomanian rudists are reported from the lower part of the Abu Qada Formation from the Metoicoceras geslinianum ammonite Zone of Zakhera (2001) (argillaceous limestone), including Eoradiolites cf. davidsoni (Hill). In the higher Vascoceras cauvini ammonite Zone (argillaceous limestone), two assemblages are reported, including Eoradiolites syriacus (Conrad) and Requienia tortuosi nov. sp. (lower level); the other assemblage (upper level; silty marl, late Cenomanian) includes Requienia tortuosi nov. sp., Toucasia carinata (Matheron), Apricardia carentonenis d’Orbigny, Eoradiolites liratus (Conrad) and Eoradiolites lenisexternus nov. sp. The reported Cenomanian rudists are associated with abundant large-sized oyster Exogyra (Costagyra) olisiponensis Sharpe, with other bivalves, gastropods, and echinoids. The early Turonian sequence just above the Cenomanian/ Turonian boundary (upper part of Abu Qada Formation) is devoid of any rudists. The Turonian rudists are reported from a higher stratigraphic level than in the Wadi El Siq section, as they are encountered within the upper part of the Choffaticeras segne Zone of the middle Turonian of the Wata Formation (dolomitic limestone), including Praeradiolites ponsianus (D’Archiac) associated with few oysters, other bivalves and gastropods. 3. Systematic paleontology Terminology and systematic classification used by Dechaseaux et al. (1969), Skelton (1978), Steuber (2002), Pons et al. (1995) and Masse et al. (2007) are followed. The following abbreviations are used: LV: left valve; RV: right valve; AV: attached valve; FV: free valve; BC: body cavity; L: ligamental ridge; lg: ligamental groove; ab: anterior band; pb: posterior band; I: interband; P1: posterior pillar; P2: anterior pillar; am: anterior myophore; pm: posterior myophore; ct: central tooth; ats: anterior tooth socket; pts: posterior tooth socket; Tt: transverse tabulae. Superfamily names end with the suffix ‘‘oidea’’ following the recommendation of the International Code of Zoological Nomenclature, Article 29A (Ride et al., 1985). The material studied is deposited in the collections of the Geology Department, Aswan Faculty of Science, Aswan, Egypt, with the prefix MZ plus locality initials and serial numbers. Figs. 4–7 illustrate the identified species.

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Class BIVALVIA Linné, 1758 Superfamily HIPPURITOIDEA Gray, 1848 Family REQUIENIIDAE Douvillé, 1914 Genus Requienia Matheron, 1843 Type species: Chama ammonia Goldfuss, 1837. Requienia tortuosi nov. sp. Fig. 4(1–8) Etymology: derived from the Latin ‘‘tortuosus’’, referring to its spiral growth. Holotype: MZMS100-1 (Fig. 4(1, 6)). Type locality: Gebel Musabaa Salama, western Sinai, Egypt. Material: fifteen shells, mostly articulated. Occurrence: lower part of the Abu Qada Formation, Gebel Musabaa Salama, western Sinai. Age: Late Cenomanian. Diagnosis: shells highly inequivalve, spirally coiled LV (few whorls) with well developed carina and fine radial striae on main part of the valve exterior, LV muscles on shell wall, RV flat to slightly convex. Description: shell small to medium in size. LV coiled. Attachment area small on the tip of the LV. Ornament nearly smooth, growth lamellae crossed by fine radial striae. Growth lines bent on the posterior side of the LV, giving two spiral fine grooves that define the two radial bands. Anterior muscle insertions are elongate on shell wall of both valves. RV small and operculiform, flat to slightly convex. Posterior muscle insertion of RV is on a projecting plate. Two teeth and one socket in RV corresponding to one tooth and two sockets in the LV. The cardinal apparatus of the LV (Fig. 4(2)) shows rounded central tooth, small ats, large pts and elongated oval pm. Remarks: the new species has the characteristic morphological features of the genus Requienia (Fig. 8). It is characterized by two spiral fine grooves corresponding to the two radial bands (ab and pb) with presence of well developed carina on LV, oblique myophoral plate of the RV parallel to the commissure. Requienia ammonia (Goldfuss) as reported by Dechaseaux et al. (1969) and Macé-Bordy (2007a) differs from the present species in having an LV with several whorls, prominent interband with two flat radial bands, posterior myophore rises above the cardinal plate and growth wrinkles. Requienia calegari Parona, 1926 (Tarlao, 2005: pl. 69, fig. 1) differs from the present species in having a more tumid shell with concentric growth lines, thin wall and wider cardinal apparatus. The present material has a uniform shell layering with coiled LV that makes it different from Requienia cf. zlatarskii Paquier from Turkey, which has lamellar anterior side and smooth posterior side (Masse et al., 2004).

Fig. 4. 1–8. Requienia tortuosi nov. sp. 1: MZMS100-1 holotype; 2 MZMS100-2, coiled LV, ct = central tooth, ats = anterior tooth socket, pts = posterior tooth socket, both filled with sediments but keeping their outlines, am = posterior myophore; 3: MZMS100-3, LV with coiled umbonal area and small attachment area; 4, 5: MZMS100-4, 4, well developed carina on LV, 5, coiled LV; 6: MZMS100-1, Holotype with radial bands ab and pb; 7: MZMS100-5, conjoined LV and RV; 8: MZMS100-6, slightly convex RV. late Cenomanian. 9–12. Apricardia carentonenis d’Orbigny, 1850. 9, 10: MZMS100-7, anterior and posterior views of both valves conjoined; 11: MZMS100-8 side view of LV; 12: MZMS100-9, side view of RV. late Cenomanian. 13–16. Eoradiolites cf. davidsoni (Hill, 1893). 13, 14: MZMS10010, RV views with smooth growth lamellae; 15: MZMS100-11, internal cast of slender RV; 16: MZMS100-12, lower part of brocken cast of RV. late Cenomanian. 17. Toucasia carinata (Matheron, 1842), MZMS100-13, left valve, late Cenomanian. 18–20. Radiolites lusitanicus (Bayle, 1857), MZWS200-14; 18: dorsa-anterior view of conjoined valves; 19: top view shows the operculiform LV conjoined with RV and radial bands; 20: horizontally oriented RV showing a clear pb. late Cenomanian. Scale bars = 1 cm.

[(Fig._ 5)TD$FIG] 414

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Genus Toucasia Munier-Chalmas, 1873 Type species: Requienia carinata Matheron, 1843 Toucasia carinata (Matheron, 1842) Fig. 4(17) 1842. Requienia carinata - Matheron, pl. 176, pl. 2, figs. 1, 2. 1867–1870. Requienia lonsdalii d’Orbigny - Pictet and Campiche, pl. 14, pl. CXLI, fig. 2a–c. 1887. Toucasia carinata - Douvillé, pl. 762, pl. 28, fig. 2. 1903. Toucasia carinata - Paquier, pp. 10, 22, 35, 41, pl. 5, figs. 4, 5, pl. 6, figs. 1, 2. 1915. Toucasia carinata - Douvillé, pl. 385, T-fig. 2, pl. 11, fig. 3, 4. 1994. Toucasia carinata - Czabalay, pp. 211, 213, pl. 1, figs. 4, 6, 7, pl. 2, figs. 2, 4, pl. 3, fig. 6. 1998. Toucasia carinata - Masse et al., pl. 196, text-fig. 3, fig. 4(3). 1969. Toucasia carinata - Dechaseaux et al., pl. N781, fig. E246, 5, E249, 2. 1998. Toucasia carinata - Schöllhorn, pl. 66, pl. 15, figs. 1– 7, text-fig. 31. 2002a. Toucasia carinata - Chikhi-Aouimeur, pl. 118, pl. 1, fig. b. 2004. Toucasia carinata - Masse et al., pl. 80, fig. 5b. 2007a. Toucasia carinata - Macé-Bordy, p. 164, fig. 3B, C. Material: two specimens from the lower part of the Abu Qada Formation, Gebel Musabaa Salama, western Sinai. Age and occurrence: this species was previously reported from the same late Cenomanian age interval in NE-Sinai (Areif en Naqa; Bartov et al., 1980). According to ChikhiAouimeur (2002b) and Masse et al. (1998, 2004), it is known: in the lower Cretaceous (Aptian) of North Africa and Europe (Algeria, Tunisia, Spain); Barremian-early Aptian (Bosnia, Bulgaria, Turkey, France, Yugoslavia, East Serbia); late Barremian-Albian (Hungary, western Black Sea); late Barremian-early Aptian (Italy, Romania). Tarlao (2005) reports the species in the Cenomanian of Croatia, France, Turkey, and Italy. Description: shell medium in size, inequivalve, spirally twisted with keeled valves. A sharp carina encircles the valve from umbo to the commissure. LV larger than RV. Weakly impressed radial bands on posterior side of LV. LV tooth slightly projecting. The shell is thin and lacks internal structures and myophoral protrusions. Remarks: Toucasia patagiata (White) from the Albian deposits of Texas, differs from the present species in having a tall spiral left valve (2–3 volutions), very inequivalve, obvious attachment area, irregular keel and irregular wrinkled surface.

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T. carinata is characterized by a significant coiling; the ratio of the distance between the anterior and posterior flanks to the distance between the dorsal and ventral flanks of the RV is 0.6 to 0.7 according to Masse et al. (1998). Genus Apricardia Guéranger, 1853 Type species: Apricardia carinata Guéranger, 1853 Apricardia carentonenis (d’Orbigny, 1850) Fig. 4(9–12) 1850. Requienia carantonensis - d’Orbigny, pl. 259, pl. 592. 1901. Apricardia carentonensis - Parona, pl. 199, pl. 1, fig. 1a, b. 1903. Apricardia carentonensis - Franchis, pl. 160, pl. 6, fig. 18–21. 1973. Apricardia carantonensis - Berthou, pp. 35, 46, 97, pl. 52, fig. 2. 1983. Apricardia carentonensis - Berthou, pl. 23, text-fig. 3. 1988. Apricardia carentonensis - Accordi et al., pl. 138, text-fig. 5. 1995. Apricardia carentonenis - Mainelli, 196, fig. 2a. 1998. Apricardia carentonensis - Laviano et al., pp. 171, 174. 2005. Apricardia carentonenis - Tarlao, p. 1, fig. 3, 4, 7, 8. 2006b. Apricardia carentonenis - Chikhi-Aouimeur et al., pl. 201, fig. 2(1–5, 8,10). 2007a. Apricardia carantonensis - Macé-Bordy, p. 168, Fig. 3D. Material: four specimens, two of which are articulated shells and two right valves from the lower part of the Abu Qada Formation, Gebel Musabaa Salama, western Sinai. Age and occurrence: Cenomanian to late Cenomanian of France, Italy, Libya, Algeria, Portugal, and Croatia (Berthou, 1973; Accordi et al., 1988; Tarlao, 2005; Chikhi-Aouimeur et al., 2006b). This species is reported in this study in the late Cenomanian of western Sinai, Egypt. Description: shell small in size, inflated, attached by LV, inequivalve with RV smaller than LV. RV is characterized by myophore plate on which the posterior adductor scar appears. Both valves coiled, posterior convex, anterior concave, carina rounded, strong. Commissural plate oblique. Remarks: the morphological feature of a flat base opposite to the umbonal area suggests that some individuals settled on the substrate in a recumbent mode (Fig. 4(10)). This is the first record of this species in Egypt. The material identified as Apricardia sp. from the Maastrichtian of northern Somalia by Pons et al. (1992: pl. 222, text-fig. 4a–c) has a similar general form but A. carentonenis differs in having a smaller size, a narrower venter, and a stronger carina.

Fig. 5. 1–4. Eoradiolites liratus (Conrad, 1852), MZWS200-15; 1: right valve (RV), showing the radial costae; 2: posterior view showing the radial bands (ab, pb) and interband (I); 3: anterodorsal view showing ligamental groove (lg); 4: top view showing the operculiform LV. late Cenomanian. 5–9. Eoradiolites syriacus (Conrad, 1852). 5–7: MZMS100-16, 5, ventral view of arcuate RV, 6, dorsal view showing ligamental groove (lg), 7, posterior view showing ab, pb and I; 8: MZMS100-17, transverse section of RV; 9: MZMS100-18 straight short RV with posterior features, late Cenomanian. 10–16. Praeradiolites ponsianus (D’Archiac, 1835). 10, 11: MZMS100-19, 10, anterior view of RV, 11, longitudinal section of RV showing thick outer shell layer; 12, 13: MZMS100-20, 12, posterior view showing the folded lamella of ab and pb and the down folds of the interband (I), 13, longitudinal section of RV showing thicker outer shell layer at valve base; 14: MZMS100-21 broken RV with pointed base; 15: MZMS100-22 field view of individuals (A-E) with different orientations; 16: MZMS100-23 shows broken outer shell layer of cylindrical RV. middle Turonian. 17–19. Sauvagesia sharpei (Bayle, 1857), MZWS200-24; 17: anterodorsal view, showing the ligamental groove (lg); 18: posterior view of RV, showing ab, pb and I; 19: posterodorsal view, showing pb and I. middle Turonian. Scale bars = 1 cm.

[(Fig._ 6)TD$FIG] 416

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Family RADIOLITIDAE Gray, 1848 Genus Radiolites Lamarck, 1801 Type species: Ostracites angeiodes De Lapeirouse, 1781 Radiolites lusitanicus (Bayle, 1857) Fig. 4(18–20) 1857. Sphaerulites lusitanicus - Bayle, pl. 692. 1886. Sphaerulites lusitanicus - Choffat, pl. 32, pl. 4, figs. 2–7. 1886. Sphaerulites peroni - Choffat, pl. 33, pl. 5, figs. 1–7. 1902. Sphaerulites lusitanicus - Choffat, pl. 4, figs. 1–5. 1904. Radiolites peroni - Douvillé, pl. 246, pl. 33, figs. 7, 8. 1908. Radiolites lusitanicus - Toucas, pl. 62, pl. 11, figs. 10, 11. 1908. Radiolites peroni - Toucas, pl. 61, pl. 11, figs. 1–9. 1967. Radiolites lusitanicus - Polsak, pp. 59, 173, pl. 27, figs. 1–7, pl. 28, figs. 1–9, pl. 29, figs. 1–7. 1973. Radiolites peroni - Berthou, pl. 97, pl. 56, fig. 3. 1973. Radiolites lusitanicus - Berthou, pl. 97, pl. 55, fig. 1. 1989. Radiolites peroni - Yanin, pp. 15, 174, pl. 12, figs. 2, 3 1996. Radiolites peroni - Caffau et al., pl. 96, pl. 4, fig. 3. 1996. Radiolites peroni - Paris and Sirna, pl. 191, pl. 1, fig. 7. 1999. Radiolites lusitanicus - Steuber, pl. 95-98, pl. 15, figs. 1–6, pl. 16, figs. 1–5 (with syn. list). Material: four specimens from the Raha Formation of Wadi El Siq (level A), two with associated valves. Age and occurrence: the species is reported from Cenomanian strata in Libya, Tunisia, Portugal and Albania (Pervinquiére, 1912; Berthou, 1973; Peza and Pirdeni, 1994); Turonian in France, Greece, Slovenia, Bulgaria, Spain, Iran, Lebanon (Douvillé, 1904, 1910; Toucas, 1908; Plenicˇar, 1973; Steuber, 1999, 2002); Cenomanian to Turonian in Yugoslavia, Egypt and Italy (Polsak, 1967; Caffau et al., 1996; Metwally and Abd El Azeam, 1997); Cenomanian to Coniacian in Croatia; Turonian to Coniacian in Bosnia (Steuber, 2002). The species is reported here in the late Cenomanian of western Sinai. According to Steuber (1999), this species is reported from the late Cenomanian rocks of southwestern Europe, Albania, Egypt, Afghanistan, and Tunisia. Description: shell large in size with thick growth laminae. RV larger than the flat to slightly concave operculiform LV. RV external surface is characterized by highly folded growth laminae giving radial ornament in the upper part of the valve. On the ventral side, ab is slightly wider than pb. Ligamental ridge (L) very small, subrounded at its distal part. The interband (I) is grooved. LV has a rounded perimeter, concentrically ornamented. The outer shell layer of RV (Fig. 9(4)) is characterized by rectangular cell structures in transverse

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section. Subpolygonal cells are reported in the inner margin of the outer shell layer. Remarks: this species was originally designated as Sphaerulites lusitanicus by Bayle (1857: pl. 692). A morphological coincidence with the material described as Sphaerulites peroni Choffat, 1886 (pl. 33, pl. 5, figs. 1–7) is found. According to the priority, the older name is used and then revaluated as Radiolites lusitanicus. Steuber (1999) reviewed this issue and concluded that the number of plications in the interband was variable within the species. In addition, both taxa have been reported in the same localities and have the same stratigraphic range (Berthou, 1973; Philip et al., 1989). Radiolites matheroni Toucas (1907) of France and Croatia has a general similarity with the present material but differs in having highly raised growth lamellae of RV with narrowly folded posterior side, and having a convex operculum dome-like LV. Genus Eoradiolites Douvillé, 1909 Type species: Radiolites davidsoni Hill, 1893. Eoradiolites sp. cf. E. davidsoni (Hill, 1893) Fig. 4(13–16) 1886. Sphaerulites sharpei Bayle - Choffat, pl. 29, pl. 2, figs. 6–8 (non 1–5). Material: ten specimens, mostly RV from basal part of the Abu Qada Formation, Musabaa Salama. Age and occurrence: Late Cenomanian in western Sinai, Egypt. Eoradiolites davidsoni (Hill) is a well known species from Albian to Cenomanian rocks of Mexico, Egypt and Iran (Douvillé, 1904, 1915; Adkins, 1930). It is also reported from early to late Albian of Texas and Mexico (Scott, 1990; Alencáster and García-Barrera, 2008). Description: shell medium in size. RV slender, smooth, mostly straight, rarely slightly curved, with suborbicular outline. Interband (I) wider than pb and ab. Concentric growth lines ornament the valve surface. RV wall is composed of two layers, the inner layer thin and the outer layer thicker. The external layer with the lamellae is mostly broken away, so the valve appears smooth and the radial bands do not appear as salient ridges. LV operculiform, convex. The structure of the outer shell layer is represented by radially elongated rectangular cells in the transverse section. Remarks: Albian E. davidsoni differs from the present material in having moderately arcuate shells with prominent smooth radial bands and longitudinal costae on AV. This is a highly-variable species; its shape could be distorted by external obstacles during different growth stages; most of the variations are related with the manner of growth, such as the crowded

Fig. 6. 1–12. Eoradiolites lenisexternus nov. sp. 1, 2: MZMS100-25, ventral and dorsal views of conjoined conical RVand LVof the Holotype; 3, 4: MZMS100-26, 3, anterodorsal view of cylinderoconical RV, 4, posteroventral view of the same valve, showing the broad anterior band (ab) and the narrow interband (I); 5, 6: MZMS100-27, 5, posterodorsal view of curved conical RV, showing a fissure coinciding with the ligamental groove (lg), 6, posteroventral view of the same valve, showing the ab; 7, MZMS100-28, curved cylinderoconical RV with clear I; 8: MZMS100-29, transverse section of LV, showing the relatively thin outer shell layer, L, ab, pb and I; 9: MZMS100-30, posterior view of RV; 10: MZMS100-31, transverse section of RV, showing the outer shell layer, ab, pb and I; 11: MZMS100-32, interior view of RV, showing the transverse tabulae (Tt); 12: MZMS100-33, top view LV. late Cenomanian. 13–19. Praeradiolites biskraensis (Coquand, 1880). 13, 14: MZWS100-34, cylinderoconical RV, posterodorsal and anteroventral views respectively; 15–16: MZWS100-35, posterior and posterodorsal views of RV showing the undulating growth lamellae at radial bands (ab, pb) and interband (I); 17-18: MZWS100-36, two opposite views of slim cylinderoconical RV; 19: MZWS100-37, top view of RV showing short triangular ligamental ridge (L). late Cenomanian. 20, 21. Sphaerulites agariciformis Delamétherie (1805), MZWS200-38, 20: top view showing flat, smooth, concentrically ornamented LV with rounded oscules; 21: side view showing conjoined RV and LV with thick growth layers, late Cenomanian. Scale bars = 1 cm.

[(Fig._ 7)TD$FIG] 418

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conditions and the topography of the substratum (Alencáster and García-Barrera, 2008). The material identified by Choffat (1886) as Sphaerulites sharpei Bayle (pl. 2, figs. 6–8, non 1–5) is considered a synonym of the present species because it has an elongate slim valve with similar ornamental feature. Eoradiolites liratus (Conrad, 1852) Fig. 5(1–4) 1852. Hippurites liratus - Conrad, pl. 234, pl. 7, figs. 47–48. 1910. Eoradiolites lyratus - Douvillé, p. 70, pl. 1, figs. 2–4; pl. 4, fig. 6; pl. 5, fig. 3. 1926. Eoradiolites liratus - Parona, pl. 33, pl. 3, fig. 10. 1926. Eoradiolites lyratus - Douvillé, pl. 346, pl. 12, fig. 1a, b. 1959. Eoradiolites lyratus - Nazemi and Grubic, pl. 946, pl. 46, fig. 4. 1995. Eoradiolites cf. liratus - Caffau and Plenicˇar, p. 231, pl. 7, fig. 1a, pl. 8, fig. 1. 1998. Eoradiolites lyratus - Masse et al., pl. 54, textfigs. 9.1–4. 2000. Eoradiolites lyratus - Skelton and Masse, pl. 92, textfig. 2.8. 2002. Eoradiolites lyratus - Steuber and Bachmann, p. 738, text-figs. 8a, b, 9a. 2002b. Eoradiolites lyratus - Chikhi-Aouimeur, pl. 61, pl. 1, figs. 3, 4. 2004a. Eoradiolites liratus - Abdel Gawad et al., pl. 293, pl. 9, figs. 8, 9. 2005. Eoradiolites liratus - El-Hedeny and El-Sabbagh, pl. 555, figs. 6–9. 2005. Eoradiolites liratus - Aly et al., pl. 256, pl. 1, figs. 4–8. 2007. Eoradiolites liratus - Mekkawy, pl. 227, pl. 4, figs. 11, 12. 2008. Eoradiolites liratus - Zakhera, pl. 18. Material: twelve specimens, majority is RV, from the Raha Formation of Wadi El Siq (level A), Wadi El Bagha and Musabaa Salama. Age and occurrence: Late Cenomanian of Egypt (in both Sinai and Eastern Desert), Morocco, Somalia and Algeria (Douvillé, 1910; Chikhi-Aouimeur, 2002b; Zakhera, 2008); early Turonian in Lebanon, Syria, Italy and Croatia (Blanckenhorn, 1890; Parona, 1926; Polsak and Mamuzic, 1969; Masse et al., 1998). It is also recorded from Turonian of Mexico, Iran and Afghanistan (Nazemi and Grubic, 1959; Steuber, 2002); Albian to Cenomanian rocks in Sinai by Douvillé (1913) and

419

Steuber and Bachmann (2002); middle Albian of Oman, Spain and SW France (Masse et al., 1997). The species is widely distributed geographically in the Tethyan realm and commonly found in the Mediterranean area. Description: shell medium to large in size, conical shape with subrounded to suboval transverse section outline. RV bears regular radial costae along the valve length crossed by growth laminae at intervals. The valve grew upward regularly with progressive diameter; ab is thinner than pb with concave surfaces. The interband (I) is represented by radial furrow, deeply sunken at the top of the valve. The ligamental groove is obvious with short trapezoidal ligamental ridge. LV operculiform with concentric lamination. The outer shell layer of RV (Fig. 9(1–3)) is characterized by rectangular cell structure in transverse section, while in tangential section it displays folded bands with regular rectangles. Compact spots are reported. Subpolygonal cells at the distal part of the outer layer of RV are encountered, leading to radial elongate rectangular cells at the outermost part of the layer. Remarks: the structure of the outermost part of the shell layer of this species could be interpreted as continuous radial ridges pattern of Pons and Vicens (2008). Eoradiolites zucchii Caffau and Plenicˇar, 1991, from the Cenomanian of Italy and Croatia differs from the present species in having thin lamellae that in places are spaced from the valve body, and the interband bears three ribs. With its ribbed shell Steuber and Bachmann (2002) considered E. liratus, an end member of a chronospecies lineage starting with Eoradiolites plicatus (Conrad, 1852) with faintly ribbed and wider radial bands, then passing to Eoradiolites murgenis Torre, 1965. Eoradiolites davidsoni (Hill, 1893) as described by Douvillé (1913) differs from E. liratus in having elongate, slim, small, thin, nearly smooth shells with some concentric lamellae at RV base and ab twice as wide as pb. Eoradiolites syriacus (Conrad, 1852) Fig. 5(5–9) 1852. Hippurites syriacus - Conrad, 266, pl. 16, fig. 84. 1867. Hippurites syriacus - Frass, pl. 85, pl. 1, fig. 7. 1929. Eoradiolites liratus var. congregate - Klinghardt, pl. 95, pl. 12–14. 1934. Eoradiolites syriacus - Blanckenhorn, pl. 225, pl. 11, figs. 93–96. Material: eight specimens, RVs and few are articulated, from Abu Qada Formation at Musabaa Salama.

Fig. 7. 1, 2. Sphaerulites agariciformis Delamétherie (1805), MZWS200-39; 1, posterodorsal view of RV, showing undulating growth lamellae giving radial ribs, stronger at the central part, 2, fracture section of the same valve, showing body cavity (BC), thin inner shell layer and thick outer shell layer, late Cenomanian. 3–9. Sphaerulites depressus Blanckenhorn (1934). 3: MZWS200-40, separated shell lamellae from the basal part of RV, showing smaller body cavity (BC); 4, 5: MZWS200-41, 4, posterior view of RV, showing the radial bands ab, pb and interband (I), 5, fractured radial section of RV, showing body cavity (BC), thin inner shell layer, thick outer shell layer and radial bands; 6: MZWS200-40, fractured tangential section of the left part of 3, showing the cellular structure; 7–9: MZWS200-42, 7, anterior view of RV, showing undulating growth lamellae giving strong radial ribs, 8, fractured section of RV, showing body cavity (BC), thin inner shell layer, very thick outer shell layer, and the commissure plate (C), 9, close up view of the spot C of 8, showing the commissure plate (CP), relicts of LV attached to RV. late Cenomanian. 10–14. Vaccinites cf. grossouvrei (Douvillé, 1894), MZWS200-43; 10, 11: two views of compact cluster, showing the external features of cylindroconical right valves; 12, 13: transverse sections at the upper third of the RV, showing cluster of individuals and the internal pillars above (12) and below (13) the transverse cutting plane; 14: close up view of 13, showing undulating inner margin of outer shell layer (right side of the photo), distinct ligamental ridge (L) and radial pillars P1 and P2, middle Turonian. 15–17. Hippurites resectus Defrance (1821), MZWS200- 44; 15: top view RV, showing relatively long triangular ligamental ridge (L) and posterior pillar (P1) shorter and thicker than the anterior pillar (P2); 16: posterodorsal view of RV, showing the L and P1; 17: posterior view of RV, showing the external grooves corresponding to internal pillars P1, P2 and L. middle Turonian. Scale bars = 1 cm.

[(Fig._ 8)TD$FIG] 420

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Fig. 8. Sketch drawing showing the morphology of the genus Requienia (modified after Cestari and Sartorio, 1995).

Age and occurrence: Late Cenomanian of western Sinai of Egypt and Cenomanian of Syria, Lebanon and Palestine (Frass, 1867; Blanckenhorn, 1934). Description: shell medium to large in size, upright conical to arcuate shape. The attached valve is the RV; it grew by different rates, giving a narrow base and broad top. RV ornamented by regular weak radial ribs evenly spaced around the shell, crossed by faint growth laminae ab broader than pb. The interband (I) narrow. The ligamental groove is obvious and narrow. LV thin, operculiform with closely spaced concentric lamination. The outer layer structure of RV (Fig. 9(5, 6)) is characterized by regular rectangular cells interlayered with compact structure in the transverse section. Remarks: the present species differs from Eoradiolites liratus (Conrad, 1852) in having less pronounced smooth radials with narrow interspaces, mostly arcuate shells and different radial bands width. It is very similar to Eoradiolites adriaticus Caffau and Plenicˇar, 1994 (Tarlao, 2005) from Italy and Croatia, but the latter has an elongate slender RV with widely spaced, sharp vertical ribs, highly undulated posterior region, and thin flat LV. Eoradiolites lenisexternus nov. sp. Fig. 6(1–12) Etymology: derived from the Latin words ‘‘lenis’’ as smooth and ‘‘externus’’ as exterior, referring to the smooth exterior. Holotype: MZMS100-67 (Fig. 6(1, 2)). Type locality: Gebel Musabaa Salama, western Sinai, Egypt. Material: fourteen specimens of both valves. Age: Late Cenomanian of the western Sinai of Egypt. Occurrence: Lower part of the Abu Qada Formation, Musabaa Salama, western Sinai. Diagnosis: conical to cylinderoconical RV, thick walled; LV rounded domal; transverse tabulae on RV interior; low rounded ligamental ridge; smooth growth laminations on RV surface; no longitudinal radial ribs. The outer shell layer of RV shows rectangular cellular structure.

Description: shell medium in size, attached by RV. RV conical to cylinderoconical shape, curved to moderately arcuate. Conical forms are shorter. Thick walled RV. Distinct transverse tabulae impressed on the interior of the right valve surface with interspaces wider than the tabulae (Fig. 10). RV ornamented by smooth broad growth laminations with even surfaces. Ligamental ridge low, triangular, truncated at its distal part. The radial area is represented by folded lamination. The convex upward growth lines mark the interband ab is wider than pb but has the same attitude, separated by narrow interband (I). In the transverse section, the outer layer of RV (Fig. 9(7)) shows rectangular cellular structure. The rectangular cells are of different size and orientations, and arranged radially in alternative zones. LV smaller than RV, rounded, domal, operculiform and concentrically laminated. Remarks: the present material differs from other Eoradiolites species in having no obvious radial ribs or rough lamellae. This new species has internal transverse tabulae similar to Eoradiolites (Dechaseaux et al., 1969: pl. N760, fig. E229). The conical form of the present species is somewhat similar to Radiolites scotti Alencáster and García-Barrera, 2008 from the Albian of East-Central Mexico, but the latter is shorter and differs in the nature of radial bands and the style of ornamentation. Some varities of the material identified as Radiolites lewyi obtusus Parnes, 1987 from the Turonian of Gebel Er-Risha, northeast Sinai, show some similarity to the conical forms of this new species but R. lewyi obtusus differs in having strong external lamellae that are recurved and arched in ab and become concave in the interband. The material identified as Sphaerulites cf. foliaceus? (Blanckenhorn, 1934: pl. 229, pl. 12, fig. 1, non fig. 2) is quite similar to the present species and could be included within it. The high convex LV, which is the free valve is somewhat similar to the genus Radiolites but the new species does not have strong ribs or shallow depressed radial bands. The presence of cylinderoconical and conical forms reflects a specific habitat related to density of individuals and sedimentation rate. The variability of shell form is achieved by other Eoradiolires species (El-Hedeny and El-Sabbagh, 2005). Genus Praeradiolites Douvillé, 1902 Type species: Radiolites fleuriaui d’Orbigny, 1842. Praeradiolites ponsianus (D’Archiac, 1835) Fig. 5(10–16) 1835. Sphaerulites ponsiana - D’Archiac, pl. 182, pl. 11, fig. 6a–g. 1850. Radiolites ponsiana - d’Orbigny, pl. 210, pl. 552, figs. 1–5. 1904. Praeradiolites ponsianus - Douvillé, pl. 244, pl. 33, figs. 1, 2, 4. 1907. Praeradiolites ponsianus - Toucas, pl. 30, pl. 3, figs. 3, 4. 1913. Praeradiolites ponsianus egyptiaca - Douvillé, pl. 248, pl. 2, figs. 1, 2. 1971. Praeradiolites ponsianus aegyptiacus - Berizzi Quarto Di Palo, pl. 524, pl. 39, fig. 11. 1987. Durania humei Douvillé - Kora and Hamama, pl. 296, pl. 1, fig. 10.

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421

1999. Praeradiolites ponsianus - Steuber, pl. 91–92, pl. 12, figs. 1, 2, text-fig. 38A (with syn. list) 2004a. Praeradiolites ponsianus aegyptiacus - Abdel Gawad et al., pl. 9, figs. 7, 10. 2005. Praeradiolites ponsianus - Aly et al., pl. 259, pl. 3, figs. 4–6, pl. 4, figs. 1–5. 2007b. Praeradiolites ponsianus - Macé-Bordy, pl. 78, fig. 2D–F; fig. 3D, E.

1972. Praeradiolites biskraensis - Bartov et al., pp. 72, 75, text-fig. 3. 1994. Praeradiolites biskraensis - Razgallah et al., pl. 508, text-figs. 2–4, 6, 17. 2002a. Praeradiolites biskraensis - Chikhi-Aouimeur, pl. 121, pl. 2, fig. b. 2004a. Praeradiolites biskraensis - Abdel Gawad et al., pl. 285, pl. 9, figs. 1,3.

Material: ten specimens, mostly broken RV, from lower part of the Wata Formation, Musabaa Salama. Age and occurrence: Middle Turonian of western Sinai, Egypt. Turonian of France, Algeria, Iran, Lebanon, Greece and Croatia (Toucas, 1907; Parona, 1935; Polsak and Mamuzic, 1969; Steuber, 1999); Cenomanian-Turonian of Tunisia (Pervinquiére, 1912; Berizzi Quarto di Palo, 1971). Description: shell medium in size, attached by cylindrical, thick walled RV. Growth laminae of RV tightly and smoothly constructed; ab and pb defined by folding of growth lamination. Interband (I) wider than the radial bands and defined by down folding of the growth lamination towards the valve base. RV attachment base tapered; LV almost flat. The outer shell layer of the RV (Fig. 9(8)) is composed of polygonal (penta-hexagonal) cellular structure; the innermost part of the layer shows rectangular cells, parallel to the layer surface by their longer diameter. Remarks: the material identified by Kora and Hamama (1987) as Durania humei Douvillé has obvious folded growth lamella defining the radial bands ab and pb, so the material is included as a synonym of the present species. Radiolites lewyi obtuses Parnes, 1987 (pl. 142, pl. 3, figs. 9–13) from late Turonian of northeast Sinai has an external ornamental similarity with the present species. Douvillé (1913) mentioned that the only difference between Praeradiolites var. aegyptiaca and P. ponsianus is the presence of additional folded lamellae posterior to the posterior band of the earlier species. This feature was observed in RVof Boeotian material of P. ponsianus (Steuber, 1999). Sphaerulites peroni Choffat of Dacqué, 1903 (pl. 375, pl. 36, figs. 1, 2) was considered to be a synonym of Praeradiolites ponsianus egyptiaca Douvillé (Steuber, 2002). In his database Steuber listed P. ponsianus and P. aegyptiaca as separate species according to their references, but in his paper on rudists of Boeotia, he lumped them together as synonyms (Steuber, 1999). The material identified by Dacqué (1903) as Sphaerulites peroni Choffat has undulating prominent concentric growth lamellae on the attached RV and thus differs from the present species.

Material: fourteen specimens, mostly RV and associated valves, some of which are broken or fragmented from the Raha Formation of Wadi El Siq (level C). Age and occurrence: Late Cenomanian of western Sinai, Egypt, and Tunisia, Libya, Palestine (Parona, 1921; Bartov et al., 1972; Razgallah et al., 1994). Turonian of Algeria, and Croatia (Polsak and Mamuzic, 1969; Chikhi-Aouimeur, 2002a). Description: shell medium in size, conical to cylinderoconical, slender at base, wide at top, attached by RV. Ligamental ridge short, triangular. Ligamental groove deep. RV ornamented by tight smooth folded growth lamellae, become protruding in the upper part of the valve. Thin short radial riblets also appear on the upper part of RV. Radial band expressed as folded laminations. RV devoids of strong longitudinal ribs. The outer layer of RV (Fig. 11(1, 2, 8)) is composed of rectangular cellular structure in the transverse section. The cells appear elongated in the longitudinal section. Remarks: the late Cenomanian sequence yields P. biskraensis, which is a widespread species and always found below Neolobites vibrayeanus along the southern margin of the Tethys. P. biskraensis is a good marker from Morocco to the Middle East (Chikhi-Aouimeur et al., 2006a, 2008). The exfoliation of the external protruding folded lamination makes most of the specimens appear smooth (Fig. 6(17, 18)).

Praeradiolites biskraensis (Coquand, 1880) Fig. 6(13–19) 1880. Sphaerulites biskraensis - Coquand, pl. 194. 1889–1893. Radiolites biskraensis - Peron, pl. 286, pl. 28, figs. 17–19. 1912. Praeradiolites biskraensis - Pervinquiére, pl. 307, pl. 21, figs. 10a, b, pl. 23, figs. 3a, b, 4. 1971. Praeradiolites biskraensis - Berizzi Quarto Di Palo, pl. 522, pl. 39, figs. 7, 8.

Genus Sphaerulites Lamarck, 1819 Type species: Sphaerulites foliaceus Lamarck, 1819 Sphaerulites agariciformis Delamétherie, 1805 Figs. 6(20, 21) and 7(1, 2) 1805. Sphaerulites agariciformis - Delamétherie, 396, pl. 57, fig. 12. 1825. Sphaerulites agariciformis - Blainville, 516, pl. 57, fig. 1. 1887. Radiolites foliaceus Lamarck - Fischer, pl. 1065, textfig. 821. 1840. Hippurites agariciformis - Goldfuss, pl. 298, pl. 164, figs. 1a, b. 1850. Radiolites agariciformis - d’Orbigny, p. 200, pl. 544 et 545. 1903. Sphaerulites peroni Choffat - Dacqué, pl. 375, pl. 36, figs. 1, 2. 1908. Sphaerulites foliaceus Lamarck - Toucas, pl. 52, pl. 9, figs. 2, 3, text-figs. 22–25. 1934. Sphaerulites foliaceus - Blanckenhorn, pl. 228, pl. 11, figs. 99, 100. 1969. Sphaerulites foliaceus - Dechaseaux et al., pl. N810, fig. E220, 5, E240, 2.

[(Fig._ 9)TD$FIG] 422

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[(Fig._ 10)TD$FIG]

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articulated valves

RV (interior)

423

LV (transverse section) LV (outside)

LV

RV

Tt

lg

C D B

1cm

A Fig. 10. Eoradiolites lenisexternus nov. sp. A: Articulated LV and RV with ligamental groove (lg); B: Thick external layer of RVand transverse tabulae (Tt); C: Thin external layer of LV in transverse section; D: Domal LV from outside.

1988. Sphaerulites foliaceus - Yanin, pl. 288, pl. 17, fig. 5. 1992. Sphaerulites foliaceus - Lupu, pl. 354, text-figs. 6, 7. 2007b. Sphaerulites agariciformis - Macé-Bordy, pl. 94, fig. 1G. Material: eight specimens, including RV and a few LV from the Raha Formation in Wadi El Siq and Wadi El Bagha. Age and occurrence: Late Cenomanian of western Sinai, Egypt; also in Syria, Palestine, and Lebanon (Blanckenhorn, 1934). According to the database of Steuber (2002), the socalled S. foliaceus was reported in Cenomanian of Afghanistan, Belgium, France, Spain, Romania, Slovenia, and Libya. Description: shell medium to large in size, vase shape. RV broad flattened, foliaceous. External wall weakly undulating giving radial ribs on the main part of the RV, crossed by concentric growth lamellae. Ligamental ridge (L) elongated pb deeper than ab. Interband (I) raised, as wide as both bands (depressed), bearing two less prominent costae. LV flat, smooth, concentrically ornamented, bearing rounded oscule. The outer layer of RV shows coarse rectangular, radially elongated cellular structure in the transverse section (Fig. 11(3, 4)). Remarks: Sphaerulites and Praeradiolites cannot be applied to pre-Cenomanian Radiolitidae. Eoradiolites was the foremost genus in late Aptian-Albian times in terms of species biodiversity (Masse et al., 2007). Eoradiolites cantabricus of the northwestern Mediterranean Tethyan margin may have been the ancestor of Sphaerulites (Masse et al., 2007). S. agariciformis is considered the prior synonym of S. foliaceus Lamarck (1819) according to Blainville (1825) and Macé-Bordy (2007b). Sphaerulites depressus Blanckenhorn, 1934 Fig. 7(3–9) 1934. Sphaerulites depressus - Blanckenhorn, pl. 229, pl. 12, figs. 104–106.

Material: eight specimens, mostly RV, from the Raha Formation of Wadi El Siq (level B). Age and occurrence: Late Cenomanian of western Sinai, Egypt. Cenomanian of Syria, Lebanon and Palestine (Blanckenhorn, 1934). Description: shell large in size, vase shape with relatively small body cavity. RV broad, thick walled. External wall of the RV strongly folded, giving strong prominent radial ribs at the valve base, crossed by short concentric growth lamellae pb wider than ab. Interband high, less wide. LV flat, smooth, concentrically ornamented. The outer layer of RV (Fig. 11(5– 7)) is composed of regular rectangular structure in the transverse section. Remarks: the species is different from Biradiolites depressus Toucas, 1909 from early-middle Santonian of France. The material identified as Radiolites depressus (Cornalia and Chiozza) by Parona (1926), which is known in the Coniacian of Croatia and Santonian-Campanian of Italy and Iran (Steuber, 2002; Tarlao, 2005), is completely different from the present material in shell size and shell features. The big, thick shell, small shell cavity and the layering style of the species recall Praeradiolites hoeninghausi (Des Moulins, 1826) from the Maastrichtian of northern Somalia described by Pons et al. (1992: pl. 235, text-fig. 18a, b). Sphaerulites is characterized by foliaceous growth laminae, undulating, depressed radial bands flanked by folds and corresponding internally with two convex inward bulges (Masse et al., 2007: pl. 698). Genus Sauvagesia Choffat, 1886 Type species: Sphaerulites sharpei Bayle, 1857. Sauvagesia sharpei (Bayle, 1857) Fig. 5(17–19) 1857. Sphaerulites sharpei - Bayle, pl. 690.

Fig. 9. 1–3. Eoradiolites liratus (Conrad, 1852); 1: tangential fractured section of the outer layer of RV, the right side of the photograph leads to longitudinal section; 2: magnification of the middle part of 1; 3: transverse polished section at the distal part of the outer layer of RV, showing subpolygonal cells, leading to radial elongate rectangles at the outermost part of the layer. 4. Radiolites lusitanicus (Bayle, 1857), transverse fracture section of the outer layer of RV. 5, 6. Eoradiolites syriacus (Conrad, 1852); 5: transverse polished section of the outer layer of RV, showing the cellular structure (Ce) and compact recrystalised structure (Co); 6: nearly squarecell network of the cellular structure in transverse section. 7. Eoradiolites lenisexternus nov. sp., transverse polished section, showing the rectangular cellular structure, the rectangles are of different diameter and arranged radially as zones in rhythmic manner. 8. Praeradiolites ponsianus (D’Archiac, 1835), transverse polished section, showing polygonal (penta-hexagonal) cellular structure, the replacement obscures the cells boundary in the middle part of the photograph.

[(Fig._ 1)TD$FIG] 424

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1886. Sphaerulites sharpei - Choffat, pl. 29, pl. 2, figs. 1–5; pl. 3, figs. 1, 2. 1902. Sauvagesia sharpei - Choffat, pl. 171, pl. 8, fig. 14. 1967. Sauvagesia sharpei - Polsak, pp. 85, 189, pl. 46, figs. 1–5, text-fig. 24. 1969. Sauvagesia sharpei - Dechaseaux et al., pl. N811, fig. E238, 4. 1973. Sauvagesia sharpei - Plenicˇar, pl. 190, pl. 2, fig. 1; pl. 11, figs. 2, 3. 1973. Sauvagesia sharpei - Berthou, pp. 46, 54, 97, pl. 53, figs. 2–4 1989. Sauvagesia sharpei - Accordi et al., pl. 165, pl. 4, fig. 5. 1996. Sauvagesia sharpei - Caffau et al., pl. 96, pl. 5, Fig. 1, pl 9, fig. 1 1997. Sauvagesia sharpei - Höfling, pl. 73, pl. 16, fig. 3. 2002a. Sauvagesia sharpei - Chikhi-Aouimeur, pl. 121, pl. 2, fig. f. 2003. Sauvagesia sharpei - El-Sabbagh and El-Hedeny, pl. 252, pl. 3, figs. 2–4. 2006a. Sauvagesia sharpei - Chikhi-Aouimeur et al., pl. 203, fig. 6. Material: three RV, 2 from Wadi El Siq and one from Wadi El Bagha. Age and occurrence: Middle Turonian of western Sinai, Egypt; also Turonian of Algeria and Iran (Toucas, 1909; Steiger, 1966). The species is well known in the Turonian of the Mediterranean Provinces (Toucas, 1909; Carbone et al., 1980). It is also reported from Cenomanian-Turonian of Albania, Bosnia, Croatia, Italy, Slovenia, Yugoslavia, and Bulgaria (Steuber, 2002), and from the Cenomanian of Algeria (ChikhiAouimeur, 1998; Chikhi-Aouimeur et al., 2006a), France, Greece, Oman, and Portugal (Steuber, 2002). Description: shell medium in size. RV cylinderoconical, outer shell layer thick. Ornament of RV consists of longitudinal ribs. Radial bands broad, concave, pb wider than ab. Interband (I) raised bearing two or three prominent costae. Ligamental ridge (L) not preserved in the present material but ligamental groove (lg) is observed on the internal cast of the AV. The growth laminae are observed within some broken specimens. Remarks: the material identified by Choffat (1886: pl. 2, figs. 6–8, non figs. 1–5) as Sphaerulites sharpei seems to be related to other radiolitid species because it has an elongate slim valve with different ornamental features, so it is not considered synonymous with the present species. Sauvagesia nicaisei Coquand var. multicostata Sequenza (Pervinquiére, 1912: pl. 315, pl. 21, figs. 13a, b) from the Cenomanian of Tunisia differs from the present species in having deeper radial bands and a narrow interband, crossed radially by two costae of the same strength like the ornament of the reminder shell. Sauvagesia herekeina Özer (1994: p. 5, pl. 1, fig. 5, 6) from the

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Maastrichtian of Turkey differs from the present species in having a conical lower valve and a flat interband. Family HIPPURITIDAE Gray, 1848 Genus Hippurites Lamarck, 1801 Type species: Hippurites bioculata Lamarck, 1801. Hippurites resectus Defrance, 1821 Fig. 7(15–17) 1821. Hippurites resecta - Defrance, pl. 195, pl. 21. 1895. Hippurites resectus - Douvillé, pl. 168, pl. 26, figs. 1– 3. 1910. Hippurites (Hippuritella) resectus - Douvillé, pl. 38, 66, pl. 2, fig. 6, text-figs. 39–41, 62–65. 1913. Hippurites (Hippuritella) resectus - Douvillé, pl. 241, text-fig. 1. 1975. Hippurites (Hippuritella) resectus - Plenicˇar, pp. 90,108, pl. 2, figs. 1, 2. 1989. Hippurites resectus - Pascual et al., pl. 218, text-fig. 3. 1993. Hippuritella resecta - Steuber, pl. 39, text-fig. 3c, d. 2006a. Hippurites resectus - Chikhi-Aouimeur et al., pl. 23. 2007. Hippurites resectus - Chikhi-Aouimeur, pl. 213, fig. 2a. 2007. Hippurites resectus - Oviedo et al., pl. 309. Material: three specimens of RV from the Wata Formation of Wadi El Siq. Age and occurrence: Middle Turonian of western Sinai, Egypt. Hippurites resectus is a cosmopolitan species originally described from Uchaux, France. It is considered characteristic for the late Turonian (Oviedo et al., 2007). The species is reported from middle to late Turonian of Tunisia, Algeria, Syria, Lebanon, France, Greece, Croatia, Italy, Turkey, Bosnia, Bulgaria, and Slovenia (Steuber, 2002; Özer et al., 2009). It is also reported from the Coniacian of Spain and France (Pascual et al., 1989). Steuber (1999) mentioned the species is of middle to late Turonian in the Mediterranean region. Description: shell medium in size, cylindrical with nearly oval transverse section. RV (attached valve) larger than LV (free valve), which is operculiform and slightly convex. Three lengthwise external furrows corresponding to the radial pillars. Ligamental ridge (L) relatively long, triangular, inward tapering and truncated at its end (Fig. 12). P1 is shorter and thicker than P2, which is angled towards the ligament and pinches at its base. The badly preserved LV is ornamented by radial costae with rounded pores. Remarks: Hippuritella is generally known to be different from Hippurites in having simple or denticulate pores in the FV (Dechaseaux et al., 1969). The nature of the ligamental ridge and the posterior features support the affiliation of the present material to Hippurites rather than to Hippuritella. The present material is very similar to those described by Bandel and Mustafa (1996: pl. 615, pl. 6, figs. 1–3; pl. 7, figs. 1–6) as

Fig. 11. 1, 2, 8. Praeradiolites biskraensis (Coquand, 1880); 1: longitudinal fracture section of the outer layer of RV, showing the elongate rectangular cells; 2: transverse fracture section of the outer layer of RV, showing the rectangular cell structure; 8, tangential section at the top part of the RV. 3, 4. Sphaerulites agariciformis Delamétherie (1805); 3: transverse fracture section of the outer layer of RV, showing the coarse rectangular, radially elongated cellular structure; 4: transverse polished section. 5, 6, 7. Sphaerulites depressus Blanckenhorn (1934); 5: transverse fracture section, showing the rectangular cell structure, 6: tangential fracture section of growth laminae at the middle part of RV; 7: transverse fracture section of growth laminae at the middle part of RV, showing the coarse regular rectangular cell structure.

[(Fig._ 12)TD$FIG] 426

[(Fig._ 13)TD$FIG] (2011) 409–433 M.S. Zakhera / Geobios 44

L

C

3'pm

P1

1'

E B

A

P2

L 3'

1 cm Fig. 12. Sketch drawing of a polished slab of a transverse section of Hippurites resectus Defrance (1821). 1’ = anterior tooth socket; 3’ = posterior tooth socket in RV; pm = posterior myophore. Dark solid lines represent shell layering.

D

pm

1'

P1 P2 1 Cm

Hippurites requieni Matheron, 1842. Although H. requieni has a shorter ligamental ridge and a longer P2, both species seems to be related. Hippurites libanus Douvillé, 1910 (pl. 67, pl. IV, figs. 7, 8, text-fig. 66) differs from the studied species in having closer P1 and P2. The studied species differs from Hippurites canaliculatus Rolland du Roquan, 1841 (Macé-Bordy, 2007c: p. 11, fig. 3A, B) from the Santonian of France in having a different transverse section outline, a larger ligamental ridge, and a shorter more inflated P2. The studied material of H. resectus has a relatively longer, inward tapering ligamental ridge, which lies within the variability range of this species as figured by Douvillé (1913). Tarlao (2005) reported Hippuritella resectus Defrance from the Turonian of Italy, but this material has a short triangular ligamental ridge and P2 has a tapering base and a tumid end. Özer and Sarı (2008) and Sarı and Özer (2009) identified Hippuritella resecta (Defrance) from Turkey. The Turkish material is generally comparable to the present material but they have a longer P2 with tapering base. Genus Vaccinites Fischer, 1887. Type species: Hippurites cornuvaccinum Bronn, 1831. Vaccinites cf. grossouvrei (Douvillé, 1894) Fig. 7(10–14) 1894. Hippurites grossouvrei - Douvillé, pl. 118, pl. 18, figs. 1–4. 1904. Vaccinites grossouvrei - Toucas, pl. 97, pl. 14, figs. 1, 2, text-figs. 103, 152, 153. 1910. Hippurites (Hippuritella) grossouvrei - Douvillé, pl. 67, text-figs. 69, 70. 1934. Hippurites grossouvrei - Blanckenhorn, pl. 232, pl. 12, fig. 112. 1956. Vaccinites praesulcatus - Rengarten, pl. 133, pl. 2, figs. 4a, b, 5a, b, pl. 3, fig. 1a, b, text-figs. 5–7. 1969. Vaccinites grossouvrei - Pamouktchiev, pl. 5, pl. 2, Fig. 1, pl. 3, fig. 1. 1984. Vaccinites grossouvrei - Bilotte, pl. 41, fig. 4. 2001. Vaccinites grossouvrei - Sanders, pl. 165. Material: three RV and two associated valves from the Wata Formation of Wadi El Siq and Wadi El Bagha. Age and occurrence: V. grossouvrei is mainly reported in the late Turonian of Austria, Bulgaria, Greece, Lebanon,

Fig. 13. Sketch drawing of a polished slab of the transverse section of a cluster of Vaccinites cf. grossouvrei (Douvillé, 1894). A. relatively complete individual with preserved filled posterior tooth socket (3’) and anterior tooth socket (1’); posterior myophore (pm). B, C, D, deformed individuals; E, undulating inner margin of an outer shell layer.

Slovenia; in the middle-late Turonian of France and Bosnia; Turonian of Iran; early Turonian of Algeria; Cenomanian-late Turonian of Syria, Palestine and Yugoslavia (Douvillé, 1910; Blanckenhorn, 1934; Pamouktchiev, 1969; Plenicˇar, 1973; Bilotte, 1984; Sanders, 2001; Steuber, 2002). This is the first record of the species in Egypt. Steuber (1999) reported V. cf. grossouvrei (Douvillé, 1894), but with pillars of different morphology, from Boeotia, central Greece, and mentioned that this species is of middle to late Turonian in the Mediterranean region and of Turonian-Coniacian in Caucasus. Description: RV large, cylinderoconical; three distinct pillars P1, P2, and L occupying an interval about one third of shell circumference. Wall thickness about 0.3 cm. P1 (next to the ligamental ridge) does not have pinced base but clearly open base. P2 is thinner and twice as long as P1. Ligamental ridge (L) relatively long, tapers inwardly, generally truncated (Fig. 13). Inner margin of outer shell layer undulating. The outer surface of RV has longitudinal ribs separated by furrows. LV, which represents the free valve is flat to slightly convex; pores reticulate or denticulate with two oscules. Remarks: the species is very close to some varieties of Vaccinites grossouvrei (Douvillé, 1910: text-figs. 69, 70), which has a slightly open base of P1. Also the present material has a P2 with less narrow base. Vaccinites gosaviensis (Douvillé, 1890) from the Santonian-Campanian of Austria differs from the present species in having thicker shell wall, relatively narrower body cavity, the P2 pillar twice as long as P1 both having pinced bases. The present species bears some similarity with Vaccinites marticensis (Douvillé, 1891) from the Coniacian of Spain (Troya and Vicens, 2008) but the latter species differs in the length of the L-P2 interval and the shape of the L and P2 pillars. Vaccinites rousseli (Douvillé, 1894), which was reported from France and Algeria (Chikhi-Aouimeur, 2007), differs from the present species in the nature and diameter of the radial area (less undulating) that occupies about

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one quarter of the valve circumference, and by the morphology of the P2 pillar, which is relatively shorter with a tumid end. 4. Paleoecology of rudists in the western Sinai Rudists are a peculiar group of bivalves with sessile shells that were adapted to filter feeding trophic regime. Many forms show strong development of the attached valve and the subsequent reduction of the free valve. In general form, rudists resemble corals and it has been suggested that rudists replaced corals in reefs during the Cretaceous (Kauffman and Sohl, 1974; Johnson and Kauffman, 1996). In places rudist buildups coresponded to a different environment than corals (Scott, 1988). Scott (1990) and Gili et al. (1995b) showed that an environmentally induced vertical succession of corals to rudists formed in response to changing depositional settings. It is believed that rudists lived in environments similar to those populated by corals, usually warm, shallow and well oxygenated waters; however rudist-dominated assemblages characterised restricted (Scott, 1988) to hypersaline waters (Johnson and Kauffman, 1996). Some rudists may have been able to suck in water through the perforated left valve (Clarkson, 1993). 4.1. Classification of rudist morphotypes in western Sinai Skelton and Gili (1991) have suggested three ecological morphotypes for rudist shells based on their life orientation:  the elevators grew with a vertical to subvertical growth pattern, maintaining their commissure almost parallel to the sediment-water interface, with a small basal attachment area. They may have been largely buried within the sediment (Ross and Skelton, 1993). Kauffman and Sohl (1974) suggested that most elevators were only slightly buried within the sediment, as indicated by the distribution of epibiont and boring organisms on their shells;  the clingers were attached by a complete side of the attached valve to hard substrates such as corals, hardgrounds and other rudists, and they largely occur as single specimens. The commissure was at an angle of between 458 and 908 to the sediment-water interface;  the recumbents grew horizontally and lay free with the long axis of both valves parallel to the sediment-water interface. They commonly grew in horseshoe-like shell forms. The rudists of west central Sinai had adopted either elevator or clinger morphotypes with the predominance of the first type; recumbent mode of life is rarely represented. In Wadi El Siq and Wadi El Bagha, the elevators are represented by Radiolites lusitanicus, Eoradiolites liratus, Praeradiolites biskraensis, Sphaerulites agariciformis, Sphaerulites depressus, Sauvagesia sharpei (mainly as isolated elevators), Hippurites resectus and Vaccinites cf. grossouvrei, (as isolated and cluster elevator); the clinger morphotype is not reported in these localities. In Muabaa Salama, the elevators are represented by Eoradiolites cf. davidsoni, Eoradiolites liratus, Eoradiolites

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syriacus, Eoradiolites lenisexternus nov. sp., and Praeradiolites ponsianus (as cluster elevators), while Requienia tortuosi nov. sp., Toucasia carinata and Apricardia carentonenis are clingers. Apricardia carentonenis could also achieve recumbent mode as the two valves of some specimens grew, having smooth base and the commissure at an angle of 908 to the sediment-water interface. Some individuals of Vaccinites cf. grossouvrei and Hippurites resectus (Wata Formation of Wadi El Siq and Wadi El Bagha), Praeradiolites ponsianus (Wata Formation of Musabaa Salama), Eoradiolites lenisexternus nov. sp. (lower part of the Abu Qada Formation of the Abu Qada Formation, Musabaa Salama) are reported in their life position, achieving the autochthonous fabric of Johnson et al. (2001). Other species show not in situ parautochthonous fabrics of lacking binding. Most species in the studied sections of west central Sinai show open fabrics in which the matrix supported shells with low packing. Closed fabrics are achieved by Eoradiolites liratus and Eoradiolites syriacus as they show relatively dense packing. The elevator hippuritid rudists of the circumMediterranean have been interpreted as constratal growth forms (Gili et al., 1995a; Skelton et al., 1995; Sanders and Pons, 1999). 4.2. Paleoecological indication of Cenomanian and Turonian rudists in western Sinai The three levels of the lower part of the Raha Formation at Wadi El Siq and Wadi El Bagha (Fig. 2) are characterized by the predominance of elevator morphotypes. The presence of the elevator morphotypes in this late Cenomanian sequence indicates calm environments (the elevator morphotype is linked with low energy environments; Korbar et al., 2002). The rudist beds have a matrix of lime mudstone also suggesting a low-energy environment. Many rudists are randomly oriented; this suggests high-energy episodes. This interval northwestward at Musabaa Salama is occupied by oyster banks of Ilymatogyra africana (Lamarck) and Ceratostron flabellatum (Goldfuss), indicating that the situation at Musabaa Salama was more active as it is barren of any rudists. Upwardly in Wadi El Siq and Wadi El Bagha, rudists appeared in the late Turonian part of the Abu Qada Formation represented by elevators belonging to Vaccinites, Hippurites and Sauvagesia in dolomitic marl facies. These elevators grew longer with less tumid shells that may indicate a higher sedimentation rate in deeper conditions than those of late Cenomanian. Radiolites occupied the shallowest subtidal environments while in the deepest areas (outer shelf environment) various species of Vaccinites thrived, often as scattered individuals (Moro et al., 2002). In Musabaa Salama (Fig. 3) rudists appeared in the lower, Cenomanian part of Abu Qada Formation with elevator, clinger and few recumbent forms. The recumbent forms appeared at the higher level of this interval, together with the other morphotypes. Recumbent rudists grew during intervals of reduced or no sedimentation (Mitchell, 2002). Also the cylinderoconical forms of Eoradiolites lenisexternus nov. sp.

[(Fig._ 14)TD$FIG] 428

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Fig. 14. Randomly oriented elevator Praeradiolites ponsianus (D’Archiac, 1835) from the Wata Fm., showing toppled nearly horizontal (A), oblique (B) and nearly vertical (C) individuals.

cemented together in bouquet association; the conical forms are shorter with some curvature. This growth form may reflect a lower sedimentation rate according to Metwally and Abd El Azeam (1997). In the early Turonian sequence of Wata Formation, rudists are represented by elevator Praeradiolites in dolomitic limestone facies. Elevators were feeding in calm waters above the sediment surface and out of the zone of muddy water. None of the reported rudists show sign of encrustation, but borings are observed in some species. The any mode of occurrence revealed that they lost their upright living position (Fig. 14) due to episodic current action during life or post-mortem basin processes, which may have moved them slightly from their living position. Toppling of rudists indicates low sedimentation rates and reworking by storms (Mitchell, 2002). Presence of Requienia biostromes that lived as clingers indicates a low sedimentation rate during deposition of the lower part of the Abu Qada Formation in Musabaa Salama area. The clingers lived in environments with variable water turbulence but could not cope with high sedimentation rates (Steuber and Löser, 2000). Requieniidae species from the lower Cretaceous of the Mediterranean Tethys inhabited shallow water carbonate platforms (Masse and Philip, 1981; Masse, 1992). In United Arab Emirates the requieniid and monopleurid rudists predominate in the shelf lagoon and display a patchy distribution vertically and laterally in Aptian sediments (Hamdan and Alsharhan, 1991). The requieniids have been preserved in a muddy, quiet-water, inner-platform environment (Swinburne and Masse, 1995). Based on the inferred mode of life and taphonomic features, the Cenomanian rudist assemblage of Requienia in Musabaa Salama section is described as ‘‘Primary shell concentrations’’ of Type A of Ruberti and Toscano (2002) as they are of dense packing with a minor clastic silty matrix, slightly oblique to the bedding plane, weakly bioeroded, mostly intact and articulated. Upward in the same section within Wata Formation, the elevator Praeradiolites represents a ‘‘Primary shell concentrations’’ of Type B of Ruberti and Toscano (2002) as they are obliquely oriented to toppled, bioeroded and disarticulated. The Cenomanian Rudist assemblage of the Raha Formation and the Turonian assemblage of Abu Qada in Wadi El Siq and Wadi El Bagha are also ‘‘Primary shell concentrations’’ of Type B.

Species of Apricardia, Requienia, Toucasia, Eoradiolites, Sphaerulites, Praeradiolites, Sauvagesia, and Radiolites adopted an epifaunal life habit, and those of Hippurites and Vaccinites adopted a semi-infaunal life habit and all were of suspension feeding habit (Paleobiology database, 2008). In Wadi El Siq and Wadi El Bagha, the upper part of the Raha Formation and the lower part of the Abu Qada Formation, in the interval below and above the Cenomanian/Turonian boundary, are devoid of any rudists. In Musabaa Salama section the lower part of the Raha Formation and only interval above the C/T boundary is also devoid of rudists. The absence of rudists may be attributed to the marine transgression during latest Cenomanian, which led to sea-level rise and deeper conditions. Absence of rudist above the C/T boundary may be related to drowning of the Cenomanian platform. The global temperature was significantly warmer than today (Kaiho and Saito, 1994). This warmness may have led to drowning of the platform (Steuber and Löser, 2000). Crises in species richness and abundance during early and middle Cretaceous can be attributed to regional environmental perturbation, induced by either oceanic anoxia or tectonic movements (Steuber and Löser, 2000). Rudists are absent from the relatively deeper water of lower Turonian deposits of the Adriatic carbonate platform. Those that thrived later in the Turonian and Senonian on the Adriatic carbonate platform were sediment-dwelling elevators (Gili et al., 1995a). The paleocommunity was changed over the Cenomanian-Turonian transition in the west central Sinai. This is indicated by drop in faunal diversity, change of faunal characteristics of oysters and ammonites (Zakhera and Kassab, 2002) and absence of rudist. It seems that the shelf during the late Cenomanian-early Turonian was too shallow and the rudist paleocommunities may have been subjected to higher salinities due to decreased continental runoff or low oxygen, causing an ecological stress to the fauna. The anoxic water may have been moved up towards shorelines during the sea level rise and drowning of the shelf. The biotic changes were closely linked with global shifts in oceanographic current systems, water mass chemistry, and nutrient levels (Scott, 1995). The number of individuals per rudist species in the Western Desert (Abu Roash area) of Egypt, especially in the Turonian rocks, is higher than other populations of the same age interval in central Sinai. The rich occurrence of rudist species in Abu Roash may be related to the presence of paleohighs due to tectonic activities. These paleohighs generated shallow settings except of the sea transgression over the southern Tethyan margin. These shallowing conditions favored certain types of shallow marine reefal communities in Turonian (Hamza, 1993). 5. Paleobiogeography The type and rate of ambient sedimentation is of particular importance for the development of rudists due to their sessile, suspension-feeding habit (Steuber and Löser, 2000). Rudists thrived in a wide range of shallow marine settings (Ross and Skelton, 1993). The studied Cenomanian and Turonian rudists of western Sinai are of Tethyan affinities, especially Eastern

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Mediterranean, southern Europe and Middle East, comparable with those of North Africa. During the late Cenomanian, the requieniid rudists of western Sinai reflect strong relations with western African and Eastern Mediterranean platforms. At the generic level, Requienia is known from Balkan area in lower Aptian (Masse et al., 2004). Toucasia carinata is well known since Barremian to Albian from areas of northern south part of the Eastern Mediterranean subprovince. It seems that it migrated southwestwards to Spain and north Africa (Algeria, Tunisia and Egypt) during Aptian and Cenomanian. The Radiolites lusitanicus and Sphaerulites agariciformis link the western Sinai with western African, southern Europe, eastern Mediterranean and western Balkan areas. Eoradiolites liratus is widely distributed in Egypt, western Africa (Morocco, Algeria) and eastern Africa (Somalia), reflecting a strong connection with western Africa and North Indian Ocean subprovinces. Praeradiolites biskraensis is known in western Sinai, western Africa and eastern Mediterranean. Sphaerulites depressus and Eoradiolites syriacus seem to be restricted to the Mediterranean region as they are reported from late Cenomanian of western Sinai, and eastern Mediterranean areas (Syria, Lebanon and Palestine). Eoradiolites sp. cf. davidsoni is reported in the late Cenomanian of western Sinai, while Eoradiolites davidsoni is a well-known species from middle Albian rocks of the Caribbean area (Mexico and Texas). During the Turonian, Sauvagesia sharpei, Hippurites resectus, Vaccinites cf. grossouvrei and Praeradiolites ponsianus are reported in western Sinai. At the same time they are well known species in western Africa, southern Europe, eastern Mediterranean and western Balkan. With the current state of knowledge, we therefore conclude that during late Cenomanian, the Mediterranean area of North Africa was connected with the rest of the Tethys, with a few endemic species so far restricted to the two new species of this study. During Turonian, the Mediterranean area was limitedly exchanging faunas with the Caribbean Province. The variations in rudist distribution and diversity are controlled by the geodynamic evolution of the Mediterranean plates (Philip, 1985). The faunal differences are attributed to facies diversity and isolation degree, while similarities between areas are also evident due to geodynamic situation and tectonic evolution (Pons and Sirna, 1992). 6. Conclusions Paleontologic work in this study led to identification of fifteen rudist species, including two new ones: Requienia tortuosi and Eoradiolites lenisexternus. This is the first record of the genus Requienia in Egypt. Also, some species are reported for the first time in Egypt, including Apricardia carentonenis d’Orbigny, Eoradiolites syriacus (Conrad), Sphaerulites agariciformis Delamétherie, Sphaerulites depressus Blanckenhorn, and Vaccinites cf. grossouvrei (Douvillé). Rudist abundance generally declines from Cenomanian to Turonian in central Sinai. The clastics flux in central Sinai may have affected the rudist diversity. The rudist assemblages are

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dominated by elevator morphotypes lying obliquely or parallel to the bedding planes in imbricated or random orientations, reflecting the effect of currents or limited storms. The disappearance of rudists is the middle part of the sequence is due to deeper settings linked with a sea level rise. The absence of rudists above the Cenomanian/Turonian boundary may be related to drowning of the Cenomanian platform. The distribution of the rudists with oysters and other benthic fossils in the siliciclastic and carbonate sediments of the Upper Cretaceous (Cenomanian and Turonian) sedimentary rocks in the central Sinai indicates that the sequence was deposited on a broad, shallow shelf. The paleocommunity was modified due to higher salinities or low oxygen. The predominance of elevator morphotypes and presence of some clinger and few recumbent morphotypes in the late Cenomanian sequence indicate that the environment was of low energy with low sedimentation rates but interrupted by high-energy episodes evidenced by the random orientation and toppling of elevators. In Turonian, the only elevators grew longer with less tumid shells, wich may indicate higher sedimentation rate in deeper conditions than that of late Cenomanian. The environment ranged from shallow subtidal in Cenomanian to outer shelf in Turonian. Although corals and rudist bivalves coexisted in the shallow carbonate platforms of many parts of the Tethyan Realm during most of the Cretaceous, no obvious corals are associated with the recorded rudists in western Sinai. The presence of rudists without corals reflects specific paleoecological conditions and supports the conclusion that the Cenomanian-Turonian sequence of western Sinai was deposited on a shallow shelf. The rudist species of west central Sinai are strongly related to those of North African, eastern Mediterranean (especially Middle East) and southern Europe countries. Acknowledgements I deeply thank the late Prof. A. Kassab (Assiut University) for assistance during the field work; Prof. R.W. Scott (The University of Tulsa, USA), Prof. T. Steuber (Bochum University, Germany), Prof. J.M. Pons (Autonoma Universita, Barcelona, Spain), and Prof. S. Götz (Heidelberg University, Germany) for sending their articles concerning rudists from different localities in the world; Prof. R.W. Scott and Prof. J.M. Pons for reading the manuscript and for suggestions which improved this paper. Deep appreciation to Prof. S. Özer (Dokuz Eylül University, Turkey) and an anonymous referee for reviewing the manuscript and for valuable suggestions. References Abdel Gawad, G.I., El Sheik, H.A., Abdel Hamid, M.A., El Beshtawy, M.K., Abed, M.M., Fürsich, F.T., El Qot, G.M., 2004a. Stratigraphic studies on some Upper Cretaceous successions in Sinai, Egypt. Egyptian Journal of Paleontology 4, 263–303. Abdel Gawad, G.I., Orabi, O.H., Ayoub, W.S., 2004b. Macrofauna and biostratigraphy of the Cretaceous section of Gebel El-Fallig area, northwest Sinai, Egypt. Egyptian Journal of Paleontology 4, 305–333. Abdel Gawad, G.I., Saber, S.G., El Shazly, S.H., Feleih, Y., 2008. Turonian rudists from Abu-Roash area, North Western Desert, Egypt. The 8th

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