ARCHAEORADIOLITES. A NEW GENUS FROM THE UPPER APTIAN OF THE MEDITERRANEAN REGION AND THE ORIGIN OF THE RUDIST FAMILY RADIOLITIDAE
by MUKERREM FENERCI-MASSE*, JEAN-PIERRE MASSE*, CONSUELO ARIASt and LORENZO VILASt *Centre de sedimentologie-pal.eontologie, laboratoire associe au CNRS, Universite de Provence, 13331 Marseille Cedex 03, France;e-mails: [email protected]; [email protected] tDepartamento de Estratigrafia, Instituto de Geologia Economica (CSIC-UCM), Facultad de c.c. Geologicas, Universidad Complutense, 28040 Madrid, Spain; e-mails:[email protected];[email protected]
Typescript received 7 June 2004; accepted in revised form 7 June 2005
Abstract: Archaeoradiolites gen. novo (Radiolitidae), mainly suggested to be the direct ancestor of Archaeoradiolites, characterized by radially arranged branching walls structur which in turn is considered as the progenitor of Eoradio ing the outer shell layer, includes two species, Archaeoradio lites. The onset of the Radiolitidae is associated with global lites primitivus gen. et sp. novo and Archaeoradiolites oceanic changes that favoured calcite as opposed to aragon hispanicus gen. et sp. novo (type species), the distinction of ite biomineralization. The acquisition of a porous shell which is based on size, shell habit and development of the microstructure appears, in many respects, biologically radially branching microstructure. Their geographical distri advantageous and may account for gaining a rapid bution is restricted to south-east Spain and south-west « 1 myr) ecological ability for efficient colonization and France, i.e. the Western European Tethyan margin, whereas occupation of space of the family in the earlier phase of its data from the Black Sea coast of Turkey suggest a possible radiation. extension to the Eastern European Tethyan margin. Each species has a distinct biostratigraphic distribution within Key words: rudist bivalves, Upper Aptian, new genus, bios the Upper Aptian (mainly the Gargasian). Agriopleura is tratigraphy, evolution.
THE Late Aptian-Albian marked the onset of the radi shell habit, and the radial plates, muri or walls, that are ation of Radiolitidae, which followed the mid-Aptian orthogonal to the plates, here labelled walls. Walls repre crisis that affected shallow water, carbonate platform sent salient infoldings of the plates. This organizational biotas, including rudists (Masse 1989; Masse and mode is found, for instance, in Eoradiolites davidsoni Gallo-Maresca 1997). This family is characterized by (Hill) and other, relatively advanced, forms of the genus specific attributes regarding: (I) shell structure: the cal Eoradiolites, and also in some species of Praeradiolites citic outer shell layer tends to exhibit a cellular micro and Bournonia, forms in which the resulting, cellular structure, with various geometrical patterns; (2) pattern is mainly quadrangnlar (Amico 1977). The poly myocardinal features: myophores of the left valve (LV) gonal cell geometry of the Sauvagesiinae relates to the are represented by vertical, downward-projecting plates same process (Milovanovic 1935) whereas this group into the right valve (RV), teeth are nearly equal and has been considered as a division of the Radiolitidae also project deeply in sockets or gutters of the opposite (Douville 1902). valve. Cellular structures belonging to the foregoing categor The so-called cellular structure has been attributed by ies are not observed in all Radiolitidae. For instance, a earlier workers (Palmer 1928; Boggild 1930; Douville radial irregular pattern tends to characterize the genus 1935; Milovanovic 1935; Masse and Philip 1972; Strum Katzeria Sliskovic (Sliskovic 1966; Caffau et al. 1992; and Perkins 1975; Amico 1977) to the association of two Pejovic 2002), while in Rajka Milovanovic walls are rep distinct sets of laminae or plates: the funnel plates, here resented by minute columns (Grubic 2002). Moreover, labelled plates, conforming with the overall conical outer some Radiolitidae lack any type of cellular porous microstructures, as m Gorjanovicia Polsak (Polsak 1967), 1993, 1996; Masse et al. 1992, 1998; Gallo-Maresca 1993, which has a compact outer shell, similar to that of the in press) (Text-fig. 1B). The following will focus on Late Monopleuridae. Aptian radiolitid-bearing beds where specimens of The objective of the present paper is to describe a Archaeoradiolites have been collected, mainly the AI new genus, Archaeoradiolites, found in the Upper Aptian mansa-Jumilla region, including the Carche (Masse et al. of south-east Spain, characterized by a radially branching 1992), Sopalmo (Arias et al. 1996), Sierra Larga, La Oliva, outer shell microstructure, which departs from that Caroch series, where the stratigraphic distribution of observed in other Radiolitidae, especially the subcontem rudists has been calibrated to benthic foraminifera, essen poraneous Eoradiolites. The form here described has been tially Orbitolinidae, having potential for distinguishing formerly ascribed to Eoradiolites, essentially Eoradiolites the lower and upper part of the Gargasian, and the plicatus (Hill) (Gallo-Maresca 1993; Masse 1995; Masse Clansayesian. et al. 1998). Identical or closely related forms have also The synthetic stratigraphic section of the Sierra del been reported from south-west France (Masse 1995) Carche (Aptian-Albian) (Text-fig. 2) illustrates the strati (Text-fig. lA) and the western Black Sea region of Tur graphic distribution of the two species of Archaeoradiolites key (Masse et al. 2002). Because the new taxon is the and also Eoradiolites, in the Gargasian-Clansayesian inter oldest Radiolitidae documented until now and has val. The biostratigraphic interpretation that conforms to potential to be the root of the family, we discuss its the Masse et al. (1992) former dating can be summarized relationships with both the progenitor of the Radioliti as follows: (1) Orbitolina (Mesorbitolina) pervia Douglass dae, the genus Agriopleura Ktihn, and the genus Eoradio and Dictyoconus? pachymarginalis Schroeder mark the lites Douville, formerly regarded as the origin of the Lower Gargasian; (2) Orbitolinopsis? aquitanica Schroeder family. and Poignant and Orbitolinopsis reticulata Moullade and Peybernes identify the Upper Gargasian; (3) Pseudochoffa tella cuvillieri Deloffre marks the Clansayesian. STRATIGRAPHY OF THE The tripartite division of the Upper Aptian, based on RUDIST-BEARING BEDS FROM specific micro palaeontological assemblages, is well docu SOUTH-EAST SPAIN mented on a regional scale (Arias et al. 1993, 1996) and is corroborated by sequence analysis. The Lower/Upper Radiolitidae have a significant record in the Late Aptian Gargasian boundary is marked by a major sedimentary Albian of south-east Spain where they have been reported discontinuity: a subaerial truncation surface followed by from various localities distributed in the Alicante, Valen marginal marine or continental sands and sandstones (the cia, Albacete and Murcia provinces (Arias et al. 1989, so-called Montemayor sands), with a wide regional extent.
aroch , 200 km I * • , •N • x N I exATIVA I PKOVINC..:
ATLANTIC OCEAN .,.J " FRANCE I ALBACETE )(/<:��:;; , PROVIKCE .....+-+- ( '\ X�'><�"''''K
(' /x) ..... -1-_-1-\ ,) "t'-"}(/l('...... x t�LCOY ......
, ,... ALIC�"HE PROVI'IlCE ..J MURCIA PROVINCE
MEDITERRANEAN SEA 1-__',-0 _...... ;,20. Km A
TEXT -F I G. 1. A, radiolitid-bearing locations in south-west France and south-east Spain. B, radiolitid sites in the Valencia-Albacete and Murcia provinces in south-east Spain (stars indicate fossil-bearing localities). T EX T -FIG. 2. Stratigraphic section of the Aptian-Albian of the Sierra del AGE � " Carche showing the position of Archaeoradiolites species and the FO
(first occurrence) of Eoradiolites. 0:: ID 2 w � a. a.I-- I-'-r.r- :::> 4 700 � rw...J Z ·0 « 0 - :2: I- m ri:. ...J LO W 3 « � � 0 ...J I- z « iii 2 w :;: . I- (f) z « 1 .J 0
0:: W 500 .;...;.�.� 3 D... D... ::J
zf- I- « - en « (!) 0:: «0:: (!)w S 2 0 ...J � 300
Z V « - � I- -� l- D.. «
z « - ...J I :::) 1 limeslones 0 I\i Radiolitids B C \l Polyconitids rudist sandslones W 100 F.=F. D m b::::, Requienids types o Caprinids J 1= I marls @ Solitary corals " oblique & Stromatoporoids b" I bedding � Orbitolinids i 0 0 00ids � ���i� �/��_LithocOdium 1 1 � � Oysters I Chondrodonts T Bioturbation
Aside from Archaeoradiolites these stratigraphic sist of Pseudotoucasia santanderensis (Douville), Horio sections also document the FO (first occurrence) of pleura gr. almerae Paquier and Polyconites verneuili Eoradiolites sp. sensu stricto. Associated rudists con- (Bayle). SYSTEMATIC PALAEONTOLOGY Archaeoradiolites hispanicus gen. et sp. novo Text-figures 3A, 4-16 The symbols used in the descriptions are as fo llows: LV, left valve; RV, right valve; D, dorsal side; V, ventral side; A, anterior side; P, 1992 Eoradiolites sp.; Masse et aI., pp. 209-201, pI. 4, posterior side; AV c, anteroventral carina; amp, anterior myoph fig. 7. oral plate; pmp, posterior myophoral plate; mp, myophoral plate; 1993 Eoradiolites katzeri Sliskovic; Gallo-Maresca, p. 34, at, anterior tooth; pt, posterior tooth; as, anterior socket; et, cen pI. 2, figs 2, 4. tral tooth; ps, posterior socket; L, ligament ridge; Ab, anterior 1993 Eoradiolites plicatus (Conrad); Gallo-Maresca, pp. 55- band; Pb, posterior band; Ib, interband. 56, pI. 7, fig. I. Size estimates include dDV, the dorsal-ventral diameter, and 1998 Eoradiolites plicatus (Conrad); Masse et aI., p. 206, clAP, the antero-posterior diameter of the RV, the average diam fig. 13-1. eter being (dDV + dAP)/2. Derivation of name. From Hispania, the ancient Roman name of Spain.
Order HIPPURITOIDA Newell, 1965 Type locality. Sopalmo, south-east of the city of Jumilla, Superfamily HIPPURITOIDEA Gray, 1848 Province of Murcia (south-east Spain) (Text-fig. IB); lat. Family RADIOLlTIDAE d'Orbigny, 1847 38°24'58"N, long. 1° 14'48"E.
Genus ARCHAEORADIOLlTES gen. novo Holotype. In the two slabs from sample 12077 from Sopalmo (Text-figs 4-5 ), which contains 15 serial transverse sections of Type species. Archaeoradiolites hispanicus gen. et sp. novo conjoined RVs; the holotype is labelled 12077-1; the slab and associated thin section are housed with other materials in the Derivation of name. Greek archaeo, ancient, and radiolitid, Centre de Sedimentologie-Paleontologie, Universite de Provence, intended to imply that the genus is considered a primitive mem Marseille. ber of this group.
Paratypes. Sample 12077, adjacent individuals (labelled 12077-2- Diagnosis. Conical RV and flat LV. Outer shell micro 15) from the above-mentioned slab; samples 11666 from the structure consisting of radially arranged branching walls. Sierra del Carche, 12091 from Sierra Larga (an isolated specimen) Plates virtual, fo rmed by adj oining inflated terminations and 12079 (eight isolated juvenile specimens) from Sopalmo. of the radial walls. Anterior band flattened, moderately salient, interband depressed, posterior band rounded and Additional material. Sample 10920, a slab including 11 serial salient. Ligament ridge present, myophoral organization transverse sections from Almansa. wnforming to the radiolitid type. LV with a laminated wncentric structure. Diagnosis. Moderate size [max dDV = 31 mm, clAP =
25 mm; average diameter (dDV + dAP)/2 = 15 mm], Discussion. The definition of Archaeoradiolites gen. novo conical, strongly foliated Archaeoradiolites. Radial branch fo cuses on two main attributes of the RV: radially arranged ing structure mainly developed on dorsal side, usually branching walls, and virtual plates. None of the Radiolitidae extending to anterior and posterior sides and less fre described until now possesses these two characters. Eoradio quently on ventral side. Shell foliae recording stepwise lites has a typical cellular quadrangular structure, which ontogenetic variations regarding development of radial wnsists of the combination of walls and plates (DouvilIe structure. Accordingly during growth, radial bands change 1902, 1909; Amico 1977; Coogan 1977; GalIo-Maresca from compact to septate, the anterior flat and wide, the 1993) (Text-fig. 3). Praeradiolites and Sphaerulites also dis posterior salient and located at the posteroventral edge, play a cellular structure (DouvilIe 1902; Milovanovic 1935; the interband depressed. LV with concentric porous, lam Dechaseaux et al. 1969; Amiw 1977). Katzeria is the only inated structure. Ligament ridge short with a trapezoidal fo rm having a radially arranged outer shell architecture outline and concave termination. (Sliskovic 1966; Caffau et al. 1992; Pejovic 2002), whereas in this genus the radial walls are very thick, branching appears irregular (pI. 2, fig. 1 in Caffau et al. 1992) and maiuly Description restricted to the inner shell margin (pI. 4, figs 1, 3 in Pejovic 2002). Moreover Katzeria lacks a ligamental ridge and External characters. Data from transverse and longitudinal sec possesses pseudopilIars (Sliskovic 1966). Radial structures tions combined with the observation of isolated specimens lead to the following description. are locally present (i.e. dorsal side) in Petkovicia? verajana RV conical, arcuate and slightly twisted at juvenile stage Sliskovic, figured by Steuber (1999) whereas the overall becoming straight in adult stage, except in dense aggregations organization is cellular, i.e. built after walls and plates. AVe Ab
AVe
TEXT_FIG. 3. Trm ..",,, sectiorn of typicol where the orient.tion of the 5hell oris m.y be modified during ie> from inal median d TEXT_FIG. 5. A"ha,oradioiim hiqani,,,,, holotyp•. Smal traruven. «ctiorn of the RV 5howing the over1ll1 organization. Note that in A th, vrntnJ Md, has . camp.et outermdl structure where", other «mom rut in the .dult 5hdl portion 5how radially lIITang,d wall>;D ill?)" the myopho<.J 'War.till of the LV f"'oi MyophQrlll plate> protrude from the left V&ve down into the mm! ridge with • triangular Or trap TEXT_ F IG. 1. A"hawradiolil<, hi>panicu,. A, longiudinal (n,or th, dar r Mi",,,lructur< of th, oul ronfarnu to thi> arimtation (Tat·fig. l3A-B). kyrnrnetry md d,d by • basal cortiGll by", md t Frutmte, group, cOmmOn in th, Palo<()zoic (Riling 1987); Discussion. Th, sh,1ls might hav, b' gation, might b, du, to micro dissolution, as suggested by and may invad, th, anterior and post,rior sides wh,reas T,xt-figure 14B. th, v,ntral sid, is usually compact. Only on< sp,cimen (i.,. holotyp,) has an ov,rall radial structur,. lmag' ana Di5tributioll of rh, mdi,,! structure ill the shell. Th, study lysis p,rformed on transv,rse sections (11 = 3) indicat,d of th, slabs including 14 sp,cimens (T,xt-fig. 4) shows that th, septate structur, r'pres,nts 44-100 per ant of 1hat th, radial patt,m is always present on th, dorsal sid, th, out,r shell surfac, (see abov,). Th, carina found at T EX T_ F I G. '0. ArcM T EX T_ F I G. ".ArcM 1he junction between the ventral and the anterior shdl towards the plane of symmetry of the carina, the ventral portions appears to be a critical site for the distribution portion being usuaiy compact or wi1h a limited radially of the radial structure. Radial walls tend to converge arranged structure, whereas the anterior portion is typic- branetlino wall of each folia. The corresponding curve shows that the onset of each step is marked by a compact structure (i.e. cortical layer) followed by radial walls, but each step 1.ll.��V'''"Jall plate records a reduction of the compact structure relative to \:,\"t�� '\'\\ growth band the radial one, the last having the highest value for intra "'eol·lieal layer skeletal voids. The terminal folia marks a size retreat coupled with a relative reduction of the porous structure. layer Archaeoradiolites primitivus sp. novo r Text-figures 17-19 commissure 1993 Eoradiolites plicatus (Conrad); Gallo-Maresca, p. 56, pI. 7. fig. 3. Derivation of name. After the primitive characters of the species. Type locality. Sierra del Carche, south-east of the city of Jumilla, Province of Murcia, south-east Spain (Text-fig. 1B); lat. 38°26'16"N, long. 1°09'58"E. TEXT -F I G. 12. Three-dimensional sketch of the microstructure of the outer shell layer of Archaeoradiolites Holotype. Four thin sections and slabs from sample 10769 from hispanicus (not to scale). Sierra del Carche housed with other materials in the Centre de Sedimentologie-Paleontologie, Universite de Provence, Marseille. ally septate (Text-fig. 15). The radial structure character Paratype. Five thin sections and slabs from sample 15206 from izes thickened parts of the shell whereas thin parts tend Sierra del Carche (underlying beds to the type level). to be wmpact. This distribution of the radial structure is identical to those of the cellular one in Eoradiolites, for Additional material. Five thin sections from sample 5886 from instance E. piicatus (Conrad) (Douville 1913; Chikhi Arudy. Aouimeur 1983) (Text-fig. 3B). The relative extent of radial vs. compact structure tends to increase with Specific diagnosis. Small [max dDV 18 mm, clAP = increasing shell diameter. Some relatively large sections 18 mm; average diameter (dDV + clAP)/2 = 13 mm], possess a limited septate portion (restricted to the dorsal conical, somewhat foliated Archaeoradiolites. Radial side) because the section appears to be cut between two branching structure restricted to the anterior side, some wnsecutive foliae. Because the radial structure is essen what extending to the dorsal side. Radial bands compact, tially developed within the foliae, the fo liated structure is the anterior wide and flat, fused to the posterior (inter mainly found on the dorsal side, extending to the anterior band inwnspicuous), salient at the posteroventral articu and posterior sides. lation. Ligament ridge with a Iow trapezoidal transverse outline, termination concave. LV flat or slightly upward Ontogenetic development of the radial structure. The step with a porous, laminated structure. wise growth mode of the shell is not only recorded by the tiered fitted funnels but also within the corresponding fo liae. Foliae from the initial growth stages show a com Description of material from south-east Spain pact structure (juvenile stage analogous to adult stage of Archaeoradiolites primitivus; see Text-fig. 16A), whereas External characters . Owing to the absence of isolated specimens the succeeding ones record an increasing intraskeletal the fo llowing data derive from the observation of variously ori porosity linked to increasing development of the radial entated sections. RV conical, from low to high angle, with moderate foliated walls. Four successive growth stages are illustrated on habit (Text-fig. 18A-B). Transverse outline subrounded at juven Text-figure 16C-F, each represented by a close-up of the ile stage (Text-fig. 17A), elliptical and somewhat lobate dorsally, microstructure showing that the number of radial walls and anteriorily carinate at adult stage, the carina located at the tends to increase as their thickness decreases at each anteroventral junction (Text-fig. 17B-C). Radial bands mth a growth step. This trend is documented by a quantitative compact structure, the anterior band flattened and wide, the estimate of the intraskeletal voids measured (using image posterior band salient and corresponding with the posteroventral analysis) for successive fo liae and within distinctive parts TEXT_FIG. 13. A"M vp � vp� articulation; interband incornpicuous Or hardly depr=ed (Text· juvenile st.ges, mowing mort Mymmetric myophor.J pate<. fij;. 17). Growth surface, rnmdmg from the md.l edge to the Lij;ament ridge r. mort, with • trapezoid.J to triangular mner margin of the outer mell, , 5. T EX T_ F I G. A"Mwradioiit" h�pani,,,,. A-B, microstructure of the anteroventral carina iliowing the convergence of radial wall> towards the p,ane of symmetry and the di>tinctive radial habit of the anterior and ventral side of the carina. A, Cuche, samp,e 11666. B, Sop.lmo, sample 12077. Scale bars r cent of the overall outer ilidl surface, sO signiftG>ntly 1= than Transver« «ctions of juvenie specimms and longitudmal m A"Meoradioiim hispani,,,,. «ctions of .dult specimens mainly di>play. comp.ct outerilidl Owing to the r«triction of the "dial walls to the anterior structure. The LV 511= corrugations sugg«ting a s , 16�. , intrask�etal voids % T EX T _F I G. 16. A, A"ha,oradioiim hispani,,,, .t iuvmile 1he two sp"cies are ugarded as phylogenetically related sidering Agriop!eura to be 1he anastor (Douvill� 1910; rnronosp"cies. Masst and Philip 1974) or even 1he origin of Radiolitidae (Paquier 1900; Toucas 1907; Dechaseaux et al. 1969) necessitates a discussion of 1he relationships between EVOLUTIONARY ORIGIN OF A. primitivU5 and the youngest repusentatives of Agrio ARCHAEORADIOLITES pleura. The attributes of this genus (type species Agria marticct1,is d'Orbigny) include a depussed LV, a compact Archaeoradiolitcs primitivU5 is the oldest and most primit outer shell layer and the prestnce on the LV of myoph ive representative of the Radiolitidae yet uwgniud. Con- oral bulges (distinct from true plates) flanking elongated TEXT _FIG. 111. A"M.oradioiit" primiti�u,. A. longitudinal «ction 5howing the conicol 5hdl habit of the RV and theflat 1 V. .s. sp teeth. In addition, Agriopleura- pmsess« well-defined I.e. to the centre of the valve depression. The ventral radial bands and a ligament ridge associated with a liga bands correspond to a flat, relatively wide anterior band menta! cavity. Agriopleura- belonging to the Agriopleurct and a salient posterior band forming the posteroventral blumc"lxtchi (Studer) and Agriopleura- ma-rti",,,,is (d'Omi carina (Text-fig. 21) ...mereas in the European forms each gny) group are well documented from the Barremian of band possesses a longitudinal depression bound by two France and Switzerland (Toucas 1907); they disappured fine ridges (Douville 1910, 1918). The organization of the from the European Tethyan margin in the radial bands of Archaeora-diolites hispMicu, is nearly iden latest Barremian (Masse 1995). The early Aptian Agrio tical to the late Bedoulian representatives of Agriopleura pleura- species found in Italy (Masse 1992), Lebanon from the Middle East. Differences between the latter and (Douville 1913) and the Middle East (Hughes 2003) rep Archacoradiolite, include the following: (I) in Agriopleura resent a distinct taxonomic entity (see discussion in the edges of the RV and LV are conjoined (Text-fig. 21), Masse 1992). The reference material of Agriopleum used whereas the LV of Archacoradiolite, is located within the for comparison with Archacoradiolite, comes from the depression formed by the sloping inward outer shell mar Shuaiba Formation (Upper Bedoulian) (I.-P Masse, work gin (Text-fig. 9); (2) ...mereas the size of Arabian forms of in progress) of Saudi Arabia and Oman (Shlton and Agriopleura- depends on the morphotypes (the conical Masse 2000). Two morphotypes are present: conical and ones tend to be smaller than the cylindro-conica! ones) cylindro-conical (Hugl1es 2003), both with a depressed the average size is greater than that of Archaeoradiolites asymmetric LV having grooves running from the com species; (3) myophoral plates are present in Arabian missural margin and converging towards the do"al side, forms of Agriopleura- (Text-fig. 21), a character by ...mich inner shell """ T EX T _F I G. , 9. A"ha.oradioiit" pri",iri�u,. structure of the outer iliey differ from their Europ""n homobgues, ...mereas earlier hypotheses regarding Agriopleura. as the root for ilieir dorsoventral extent is more limited ilian iliose of Radiolitidae. Size ,."duction associated with the onset of Archaeontdiolites (i.e. A. hisp""i=); and (4) the outer Archaeoradiolites and the absence of septate microstruc shell structu,." of Agriop!eura. is compact throughout its tu,."s in the juveniles of A. primitivu5 suggest derivation development. from Agriopleura. through paedomorphosis, a proas< Comparison betwetn ArcJu,"oradiolites and the late documented in some rudist lineages (Gourrat et al. Bedoulian representatives of Agriopleura. (instead of iliose 2003). of Barremian age) provides additional evidence for the dose similarity of the latter genus with primitive Radio litidae, noted mainly as Eoradiolites by many authors EVOLUTIONARY RELATIONSHIPS (I"oucas 1907; Dechaseaux et al. 1969 among others). WITH EORADIOLITES To conclude, notwithstanding generic-level diffe,."nces between Arabian forms of Agriopleura. and Archaeoradio The e,."ction of Archa.eoradiolites necessitates a discussion lites, similarities between the two genera suggest deriva of ilie relationships between iliis genus and Eora.diolites, tion of the latter from the former in accordana with which up to now was considered the progenitor of the T EX T _F I G. 20. A"/unoradioiit,, primiti�u,. Arudy. ,amp.e 5886. A. longitudim.l donovmtnl «ctim of. hivuve 'pecirnm5howing two teeth and the d Rad iolitidae (see discussion above). Stratigraphic eviden� ization as &radiolite5 sp. (Text-fig. 22). The cellular fabric documents the coexistence of Archaeoradiolite5 and the consists of: (I) radially branching walls wi1h a distal infla first rep",sentatives of &ntdiolitcs in the Upper Gargasian tion and a pronounced microbanding, associated with of Sierra del Carche (Text-fig . 2); the two genera are still micritic or relatively thick banded plates; (2) thin, elonga coeval in the Clansayesian from south-east Spain and ted, usually unbranching walls interrupted by micritic southern France. The definition of &radiolitcs must com plates. The radial branching habit closely ",se mbles that bine the organization of the radial bands (to follow of Archaeontdiolitcs, ...mereas virtual plates are replaced by Dou ville's view) and the p",sence of the quadrangular cel plates 5.5. This type of microstructu", is found, for lular habit of the outer shell layer, built of walls and instance, on the dorsal side of &radiolitcs plicatus (Text plates 5.5. (instead of virtual plates). fig. 3S). We have identified specimens found in the uppermost Likewise we assign to Eoradiolitcs sp. a form formerly Gargasian of the Sierra del Carche, with a cellular organ- placed in &mdio!itcs p!icatu5 by Masse et al. (2002) (see •. TEXT _FIG. 21. Agriopl,ura sp., Dpp« &doulim �lU'D' !'DIm.cion, Shoyb. field, S.udi Anhi A, vrntrol view showing th, ron/iguncion of th, "diolbands . .s, longitudIiol s TEXT_ FIG. 22. Eoradiolim sp., DW" Gorg.si.n, Sierra del Corch" ,ampl' 11672. A, traruvene , fig. 8, p. 531) (Text-fig . 23) found in the Upper Aptian of side and consists of radial branching walls with an inward fue Zonguldal region (western Black Sea, Turkey). In distal thickening plus micritic walls, locally somewhat fuis form the cellular structure is li mited to the dorsal incomplete. Although this form appears to be identical to TEXT _FIG. l3. Eoradiolim sp., Dpp« Aptian, Cengdlidere Form.tion, Zonguldak region,Tur kq, sampe 14146. A, transvene s Archaeomdio!itC5, the p",sena of plates warrants its place the cardinal benthic forms (forami nifera, dasycladalean ment in Eoradio!itC5. algae and rudists) thriving on shalbw carbonate plat forms. Asi de from the ",duction in the spatial distribu tion of carbonate platforms, changes In chemical ONSET OF THE RADIOLITIDAE IN THE properties of the ocean (Masse 1989) coupled with a rise EARLY GARGASIAN: BIOLOGICAL AND in Co" an increase in productivity and changes in sea PALAEOENVIRONMENTAL water saturation with respect to aragonite (Bergen 1998; SIGNIFICANCE Weissert et a!. 1998) have been suggested. The drop in biodiversity started in mid B.doulian times and contin The Onstt of the Radiolitid"" is associated with major ued across the BedoulianlGargasian boundary (Mass< global changes responsible for the mid-Aptian biolog ical 2003). The anoxic event OAE la (Arthur et a!. 1990), crisis (Masse and Philip 1986; Mass< 1989; Skelton 2003) which occurred in the Hambrovi Subzon< of the Des marked by the exti nction of 42 per cent of the generic hayesi Zone (Upper B.doulian) and pre-dates the extinc biodiversity and 57 per ant of the specific diversity of tion peak (the FurcataITobleri boundary event), was not responsible for the biological crisis for that reason, but restricted to shell portions with a compact microstruc was involved in the biodiversity decline preceding the ture, i.e. portions with radially arranged walls are free extinction peak. of borings (Text-fig. 7). Data from the Recent show that Lowering of the MglCa ratio is a good candidate to clionid sponges tend to infest various living or dead account for a change from an 'aragonite regime' to a 'cal carbonate substrates, either compact or porous, but cite regime' (Sandberg 1983; Stanley and Hardie 1998), avoid parts with a large pore size (Schonberg 2002). expressed by dasycladalean algae, aragonitic foraminifera The distribution of clionid borings in Archaeoradiolites and caprinid rudists. Linking the evolution of bivalves may only reflect this biological need; nevertheless, it is and the modification of seawater chemistry has been necessary to be aware of the global context of the coe documented by Harper et al. (1997), who stressed the dif val high seawater productivity (see above). High pro ficulty of maintaining aragonite shells in 'highly corrosive' ductivity is known to promote an increase in sponge calcite seas. By contrast with the 'Hardie model' (Hardie biomass and therefore an increase in infestation of car 1996; Steuber 2002), which predicts that a modification bonate substrates (Rose and Risk 1985). From the fore from an aragonite to a calcite regime occurs over time going it is suggested that the acquisition of a septate periods of the order of 10 myr, data from the mid-Aptian structure by Archaeoradiolites might have been advanta suggest a rapid change « 0·5 myr). Similar short-term geous for avoiding detrimental strong infestations by changes were also proposed by Pomar et al. (2004) for clionid sponges. This strategy has already been discussed the Miocene. For StanIey and Hardie (1998) the develop by Skelton (1976) for caprinid rudists. An alternative ment of the Radiolitidae was not a direct consequence of strategy, used by accompanying rudists, appears to have the mid-Cretaceous shift from aragonite to calcite seas. been an increase in shell thickness (e.g. Pseudotoucasia, They suggested that the decline of the aragonitic corals, Horiopleura) or the development of tubular structures at resulting from a decrease in the MglCa ratio of seawater, the interface between the outer and inner shell layer as, opened the way for rudists in the highly competitive reef for instance, in 'Agriopleura' darderi (Masse and Philip environments. However, as shown earlier (Scott et al. 1974). 1990; Gili et al. 1995), rudists and corals were thriving in The development of Archaeoradiolites communities, distinctive environments so that competition between the which started with Archaeoradiolites primitivus in the two groups must be ruled out. Therefore, the develop Lower Gargasian, was studied at the Sierra del Carche. ment of the Radiolitidae in the Late Aptian appears to This study was based on quantitative estimates of the fol - have been independent of the evolution of scleractinian 10wing ecological attributes (Fenerci-Masse et al. 2004): wrals, but has much to do with: (I) the vacant space left packing density (number of individuals in a 100-cm2 ver by the extinct Early Aptian Caprinidae; and (2) the onset tical surface); packing-index (number of individuals in of a calcite regime, which was also advantageous for other lateral contiguity, expressed in per cent); coverage (per weval rudists: Polyconitidae (Polyconites, Horiopleura), cent of cumulative surface covered by individuals on a Caprotinidae (Caprotina) and Monopleuridae ('Agriople given bedding plane); and skeletal contribution (ratio of ura darderi', 'Petalodontia'), all with a thick outer calcitic shell material vs. sediment in per cent). shell layer by comparison with the inner aragonitic shell Three steps were recognized in the evolution of radioli layer (Masse et al. 1998). tid assemblages of Archaeoradiolites primitivus: (1) isolated The development of a porous, septate, structure in specimens found with a requieniid-dominated community the calcitic outer shell layer of the Radiolitidae might (Pseudotoucasia) in the lowermost Gargasian (the paucity be compared with the development of the canaliculate of individuals did not permit quantitative estimates); structure observed in the originally aragonitic, inner (2) Iow-density assemblages, the quantitative attributes of shell layer of the Caprinidae. In both groups the strat which (including packing-index, packing density and egy appears likely to have minimized the cost of meta coverage) fluctuate between 0 and 0·3, associated with bolic energy used for shell production (Douville 1904; Requieniidae, in the upper part of the Lower Gargasian; Palmer 1983) and may have fa cilitated quick growth. As (3) a radiolitid community with a relatively high packing shown in modern ostreids (Chinzei 1995) vesicular index and packing density (18.5% and 16 individuals, shells allow soft-bottom bivalves to float on muddy bot respectively), moderate coverage (35%) and macroskeletal toms, an advantage for solitary individuals. This hypo contribution (16%), Archaeoradiolites primitivus being the thesis looks likely for Late Aptian Radiolitidae, which only member of this community (Bed 10769). are essentially associated with wackstones (or very fine In assemblages of Archaeoradiolites hispanicus from the packstones). Another advantage of septate structures is uppermost Lower Gargasian of Sopalmo (type level) (see the potential to resist shell breakage (Skelton 1976). A slab 12077) and Almansa (bed 10920), packing density striking fe ature of Archaeoradiolites species is the high ranges from 10 to 40, packing-index from 26 to 46 per density of sponge (Cliona type) borings, which are cent, and coverage between 55 and 70 per cent, the skeletal contribution being about 50 per cent. These high values CONCLUSIONS indicate that this species played a significant role in carbonate production and possessed a constructional A new genus, Archaeoradiolites, is described from the potential somewhat higher than that of hippuritid Upper Aptian of south-east Spain and south-west France, dominated lithosomes of the Late Cretaceous, which have characterized by the microstructure of the outer shell lower packing density and coverage (Vilardell and Gili layer of the RV, which consists of radial branching walls 2003). As fo r the hippuritid lithosomes, Gargasian radioli and virtual plates formed by adjoined, inflated termina tid-dominated beds lack relief, and their average bed tions of the radial walls. The LV is flat and possesses a thickness is reduced (less than I m), but they may, at least laminated concentric microstructure. The other organiza locally, build rigid frameworks. tional attributes, myophoral organs, radial bands and liga ment ridge, are identical to those of Eoradiolites. Archaeoradiolites includes t"vo species, A. hispanicus STRATIGRAPHIC AND GEOGRAPHICAL (type species) and A. primitivus, distinguished by the rel DISTRIBUTION OF ative development of the radial branching walls in the ARCHAEORADIOLITES outer shell layer microstructure, mainly restricted to the anterior side in A. primitivus and extending to the anter Archaeoradiolites primitivus has been recorded from the ior, dorsal and posterior sides in A. hispanicus. In A. his upper part of the Dictyoconus pachymarginalis interval panicus the RV is strongly fo liated, owing to the tiering of (Lower Gargasian) below the Montemayor Sands at fitted funnels, and shows pronounced ontogenetic varia Sopalmo, whereas it is present in beds overlying these tions regarding the microstructure of the outer shell layer. sands in the Orbitolinopsis reticulataIO.? aquitanica inter In A. primitivus the foliation of the RV is less pronounced val (Upper Gargasian) from the same locality and sur and there are also ontogenetic variations: the juveniles are rounding sites of the JumilIa area. One small specimen essentially compact. comes from the lower part of the Gargasian beds of Sierra A. primitivus is found in the Lower Gargasian and the del Carche. This species was also found in the Caroch lowermost Upper Gargasian; A. Itispanicus is present in area and at Almansa in Upper Gargasian beds. In south the uppermost Lower Gargasian and extends to the Clans west France Archaeoradiolites primitivus was fo und in the ayesian. This distribution gives to the two species of Gargasian, probably the lower part, of the Arudy area, Archaeoradiolites potential for characterizing and sub near Pau. dividing the Upper Aptian. Archaeoradiolites hispanicus has been recorded in Upper Archaeoradiolites appears to be the direct descendant of Gargasian beds from south-east Spain: Sierra del Carche, Agriopleura, probably through paedomorphosis. It was the Sopalmo, Almansa and Caroch. In the Sierra del Carche progenitor of Eoradiolites, the cellular, quadrangular this species is still present in the Clansayesian Pseudochoff microstructure of which departs from that of Archaeo atelIa cuviWeri-bearing beds. radiolites. To conclude, the stratigraphic distribution of the two The onset of the Radiolitidae is associated wi.th major species of Archaeoradiolites may be summarized as fol global changes and a strong biological crisis in mid lows: (I) Arc11aeoradiolites primitivus is fo und alone in the Aptian times. The acquisition of an outer shell layer of Lower Gargasian and together with Archaeoradiolites his porous, septate microstructure may relate to strategies panialS in the uppermost Lower Gargasian and the lower combining the minimizing of metabolic energy for shell most Upper Gargasian; (2) Archaeoradiolites hispanialS is production, the provision of some ability to float on found with primitive representatives of Eoradiolites in the muddy bottoms, and an increase in resistance to shell Upper Gargasian, then co-occurs with advanced Eoradio breakage and in ensuring protection against sponge bor lites [the so-called Eoradiolites cantabricus (Douville)] ing. This may account for the ability of Archaeoradiolites group in the Clansayesian (Masse et al. in press). to form densely packed communities with a significant Our data indicate that Archaeoradiolites appears to be bioconstructional character, acquired during the earlier restricted to south-west France and south-east Spain, i.e. phase of the radiation of the family Radiolitidae in less the western part of the European Tethyan margin. Never than 1 myr after the mid-Aptian extinction event. theless, primitive Eoradiolites from the western Black Sea coast of Turkey, close to Archaeoradiolites, suggests a Acknowledgements. Our field investigations in southern Spain direct derivation of the fo rmer from the latter and the re have been supported by a grant from the Ministerio de Cienda fore possibly the existence of Archaeoradiolites in the East y Tecnologia of Spain, project REN2001-1067/GLO (Aplicadon European Tethyan margin, known to possess strong pal de tecnicas del analisis de cuencas sedimentarias en el uso no destructivo del patrimonio natural en el Prebetico oriental. El aeobiogeographical affinities with the West European altiplano de Jumilla�Yecla). For access to and information domain during the Barremian-Aptian (Masse et al. 2002). concerning specimens in his care, we are most grateful to Mexico. University of Texas at Austin, Bureau of Economic M. Albel Prieur (Centre commun des collections de geologie, Geology, Report on Investigation, 89, 32-70 . Universite Claude-Bernard, Lyon 1). At the Universite de Pro COP E, E. D. 1887. The origin of the fittest. Appleton, New York, vence, we have benefited from the technical assistance of 467 pp. 1. Marie, P. Papi and the Centre commun de Microscopie elec DECHASEAUX, C, COX, L. R and PERKINS, B. H. 1969. tronique. Fruitful discussions with 1. Villiers, V. Chazottes (Uni Superfamily Hippuritidae Gray 1848. N749-817. In MOO RE, versite de Provence, Marseille) and M. Peyrot-Clausade (Centre R C. (ed.). Treatise on invertebrate paleontology, Part N, Mol d'Oceanologie de Marseille) were greatly appreciated. We thank lusca 6, Bivalvia, 2. Geological Society of America, Boulder, D. J. Batten (Manchester) for editorial comments, and T. Steu and University of Kansas Press, Lawrence, 951 pp. ber (Bochum) and R. W. Scott (Tulsa) for their helpful reviews. DOUVILLE, H. 1902. Classification des radiolites. Bulletin de la Societe Geologique de France, Serie 3, 36, 222-235. -- 1904. Sur quelques rudistes a canaux. Bulletin de la Societe REFERENCES Geologique de France, Serie 4, 4, 519-538. -- 1909. Sur le genre Eoradiolites novo Bulletin de la Societe Geologique de France, Serie 4, 9, 77. AMICO, S. 1977. Etude de la structure du test des rudistes. -- 1910. Etudes sur les rudistes. Rudistes de Sicile, d'Algerie, Applications a la systematique a la paleobiologie et a la pal eoecologie de ce groupe. Unpublished PhD thesis, University d'Egypte, du Liban et de la Perse. Memoires, Bulletin de la of Marseille-Provence, 90 pp. Societe Geologique de France, 41, 1-83. -- 1913. Sur quelques rudistes du Liban et sur l'evolution des ARIAS, c., MASSE, J. P. and VILAS, 1. 1989. Secuencias Biradiolitines. Bulletin de la Societe Geologique de France, Serie deposicionales en el Aptiense-Albiense, pp del Carche y 4, 13, 409-421. Sopalmo (Prov. De Murcia). XII. Congreso Espanol de Sedi -- 1918. Le Barremien superieur de Brouzet. Partie Ill: les ru mentologia, Symposium, Universidad Pais Va sco, 33-42. dites. Memoires, Bulletin de la Societe Geologique de France, ------1993. Caracterization secuencial y bioestratigra Paleontologie, 52, 1-28. fica del Aptiense-Albiense, p.p. en la Sierra de Sopalmo, -- 1935. Les rudistes et leur evolution. Bulletin de la Societe Prebetico interno (Prov. de Murcia). Boletin Geologico y Min Geologique de France, Serie 5, 5, 319-358. ero, 104, 603-612. FENERCI-MASSE, M., MASSE, J. P. and CHAZOTTES, ------1996. Relaciones tectonica-sedimentacion en el V. 2004. Quantitative analysis of rudist assemblages: a key for Aptiense de Sierra Larga, Jumilla (Murcia). Geogaceta, 20, 43-46 . palaeocommunity reconstructions. The Late Barremian record from SE France. Palaeogeography, Palaeoclimatology, Palaeo ARTHUR, M. A., BRUMSACK, H. J., JENKYNS, R. C ecology, 206, 133-147. and SCHLANGER, S. O. 1990. Stratigraphy, geochemistry GALLO-MARESCA, M. 1993. Le Radiolitidae primitive delle and palaeoceanography of organic carbon-rich Cretaceous regioni mediterranee e del sud-ouest Assiatico. Unpublished sequences. 75-119. In GINSBURG, R. N. and BEAU PhD thesis, Universita di Bari, 149 pp. DOIN, B. (eds). Cretaceous resources, events and rhythms. GILl, E., MASSE, J. P. and SKELTON, P. W. 1995. Rudists NATO Advanced Science Institutes, C, 304, 352 pp. as gregarious sediment-dwellers, not reef builders, on Creta BERG EN, J. A. 1998. Calcareous nannofossils from the lower ceous carbonate platforms. Palaeogeography, Palaeoclimatology, Aptian historical stratotype at Cassis-La Bedoule (SE France). Palaeoecology, 118, 245-267. Geologie Mediterraneenne, 25, 227-255. BOG GILD, O. B. 1930. The shell structure of the mollusks. GOURRAT, C, MASSE, J. P. and SKELTON, P. W. 2003. Hypelasma salevensis (Favre, 1913) from the Upper Kimmerid Kongelige Danske Videnskabernes Selskabs Skrifter, Naturvi gian of the French Jura, and the origin of the rudist family denskabelig og Mathematisk, Afdeling, 2, 235-326. Requieniidae. Geologia Croatica, 56, 139-148. CAFFAU, M., PIRINI RADRIZZANI, C, PLENICAR, M. and PUGLlESE, N. 1992. Rudist fauna and microfossils G RA Y, J. E. 1848. On the arrangement of the Brachiopoda. Annals and Magazine of Natural History, Series 2, 2, 435-440. of the late Senonian Monte Grisa area (Karst of Trieste, Italy). GRUBIC, A. 2002. Rajka spinosa Milovanovic from Kamilja Geologica Romana, 28, 163-171. reef at Leposavic, central Serbia. 105-109. In: Proceedings, First CHIKHI-AOUIMEUR, F. 1983. Etude paleontologique de 1988), quelques rudistes de l'Aptien superieur du Djebel Ouenza In ternational Conference on Rudists (Beograd 'Rudists '. Union of Geological Societies of Yugoslavia, Memorial Publi (Algerie nord-Orientale). Geologie Mediterraneenne, 10, cation, 322 pp. 33-48 . HARD lE, 1. A. 1996. Secular variation in seawater chemistry: CHINZEI, K. 1995. Adaptative significance of the lightweight an explanation for the coupled secular variation in the min shell structure in soft bottom oysters. Neues Jahrbuch jUr Geol eralogies of marine limestones and potash evaporites over the ogie Paliiontologie, Abhandlungen, 195, 217-227. past 600 m.y. Geology, 24, 279-28 3. -- and SEILACHER, A. 1993. Remote biomineralization I: HARPER, E. M. 1994. Are conchiolin sheets in corbulid fill skeletons in vesicular oyster shells. Neues Jahrbuch jUr Ge bivalves primarily defensive? Palaeontology, 37, 551-578. ologie und Paliiontologie, Abhandlungen, 190, 349-361. -- PALM ER, T. J. and ALPHEY, J. R. 1997. Evolutionary COOGAN, A. H. 1977. Early and middle Cretaceous Hippurit response by bivalves to changing Phanerozoic sea-water acea (rudists) of the Gulf Coast. In BEBOUT, D. G. and chemistry. Geological Magazine, 134, 40 3-407. LOUCKS, R. G. (eds). Cretaceous carbonates of Texas and HUGHES, G. W. G. 2003. Agriopleura morphotypes of the ORBIGNY, A. d' 1847. Sur les brachiopods ou palliobranches. Lower Aptian Shu'aiba Formation of Saudi Arabia. Geologia Comptes Rendus Hebdomadaires des Seances de l'Academie des Croatica, 56, 133-138. Sciences, 25, 266-269. MASSE, J.-P. 1989. Relations entre modifications biologiques et PALM ER, A. R. 1983. Relative cost of producing skeletal phenomenes geologiques sur les plates-formes carbonatees du organic matrix versus calcification. Evidence from marine gas domaine perimediterraneen au passage Bedoulien-Gargasien. tropods. Marine Biology, 75, 287-292. Geobios, Memoire Special, 11, 279-294. PALM ER, R. H. 1928. The rudists of southern Mexico. Occa -- 1992. Les Rudistes de l'Aptien inferieur d'ltalie continen sional Papers of the California Academy of Sciences, 14, 1-137. tale: aspects systematiques, stratigraphiques et paleobiogeo P A Q UI ER, V. 1900. Recherches geologiques dans le Diois et les graphiques. Geologica Romana, 28, 243-260. Baronnies Orientales. Allier, Grenoble, 410 pp. -- 1995. Lower Cretaceous rudist biostratigraphy of southern PEJOVIC, D. 2002. Sur la structure du test des Radiolitidae et France. A reference for Mesogean correlations. Revista Mexica Hippuritidae. 197-217. In: Proceedings, First International Con na de Ciencias Geologicas, 12, 236-256. fe rence on Rudists (Beograd 1988) 'Rudists'. Union of Geologi -- 2003. Integrated stratigraphy of the Lower Aptian and cal Societies of Yugoslavia, Memorial Publication, 322 pp. application to carbonate platforms: a state of the art. 203-214. PHILIP, J., AMICO, S. and ALLEMANN, J. 1977. Role des In GILl, E., NEGRA, M. H. and SKELTON, P. W. (eds). rudistes dans la sedimentation calcaire au Cretace superieur. North African Cretaceous carbonate platform systems. Kluwer Livre jubilaire Jacques Flandrin. Documents du Laboratoire de Academic Publishers, Dordrecht, 252 pp. Geologie de la Faculte des Sciences de Lyon, Hors Serie, 4, 343- -- and GALLO-MARESCA, M. 1997. Late Aptian Radio 359. litidae (rudist bivalves) from the Mediterranean and southwest POLSAK, A. 1967. Macrofaune cretacee de l'Istrie meridionale Asiatic region: taxonomic, biostratigraphic and palaeobio (Yougoslavie). Palaeontologica Jugoslavica, 8, 1-219. geographic aspects. Palaeogeography, Palaeoclimatology, Palaeo POMAR, L., BRANDANO, M. and WESTPHAL, H. 2004. ecology, 128, 101-110. Environmental factors influencing skeletal grain sediment -- and PHILIP, J. 1972. Observations sur la croissance et associations: a critical review of Miocene examples from the l'ontogenese du test des Radiolitidae (Rudistes). Conse western Mediterranean. Sedimentology, 51, 627-651. quences phylogenetiques et paleoecologiques. Comptes Ren REGIDOR-HIGUERA, L, GARCIA-GARMILLA, F. and dus de l'Academie des Sciences, Paris, Serie D, 274, 3202- ELO RZA, J. 2002. Life span and grmvth rates in radiolitid 3205. rudist shells (Hippuritacea, Bivalvia) from the Upper Creta -- -- 1974. Definition, position systematique, repartition ceous of northern Burgos (Spain). Sixth In ternational Congress stratigraphique et evolution du genre Agriopleura Kiihn (Ru on Rudists, Rovijn, Croatia, Abstracts, pp. 57-58. diste). Geologie Mediterraneenne, 1, 53-62. RIDING, R. 1987. Calcified Cyanobacteria. 45-87. In RID -- -- 1986. L'evolution des rudistes au regard des princip ING, R (ed.). Calcareous algae and stromatolites. Springer aux evenements geologiques du Cretace. Bulletin des Centres Verlag, Berlin, 571 pp. de Recherche Exploration-Produdion Elf-A quitaine, 10, 437- ROSE, C. S. and RISK, M. J. 1985. Increase in Cliona demitrix 456. infestation of Montastrea cavernosa heads in an organically -- ARIAS, C. and VILAS, 1. 1992. Stratigraphy and biozo polluted portion of the Cayman fr inging reef. Marine Ecology, nation of a reference Aptian-Albian, p.p. Tethyan carbonate 6, 345-363. platform succession: the Sierra del Carche series (oriental Pre SANDBERG, P. A. 1983. An oscillating trend in Phanerozoic betic zone-Murcia, Spain). 201-222. In KOLLMANN, H. A. nonskeletal carbonate mineralogy. Nature, 305, 19-22. and ZAPFE, H. (eds). New aspeds on Tethyan Cretaceous fos SANDERS, D. 1999. Shell disintegration and taphonomic loss sil assemblages. Osterreichische Akademie der Wissenschaften, in rudist biostromes. Lethaia, 32, 101-112. Schriftenreihe der Erdwissenschaftlichen Kommissionen, 9, 1- SCHONBERG, C. H. 1. 2002. Substrate effects on the bio 240. eroding Demosponge Cliona orientalis. Bioerosion rates. Mar 1998. Lower Cretaceous rudist fauna of ine Ecology, 23, 313-326. southern Spain: an overview. Geobios, Memoire Special, 22, SCOTT, R. W., FERNANDEZ-MENDIOLA, P. A., GILl, 193-210. E. and SIMO, A. 1990. Persistence of coral-rudist reefs into -- FENERCI-MASSE, M. and bZER, S. 2002. Late Aptian the late Cretaceous. Palaios, 5, 98-110. rudist faunas from the Zonguldak region, western Black Sea, S KEL TO N, P. W. 1976. Investigations into the palaeobiology Turkey (taxonomy, biostratigraphy, palaeoenvironment and of rudists. Unpublished PhD thesis, Oxford University, 263 palaeobiogeography). Cretaceous Research, 23, 523-536. pp. -- -- VILAS, 1. and ARIAS, C. in press. Late Aptian-Al -- 2003. Rudist evolution and extinction. A North African per bian primitive Radiolitidae (Bivalves, Hippuritoidea) from spective. 215-227. In GILl, E., NEGRA, M. H. and SKEL Spain and SW France. Cretaceous Research. TON, P. W. (eds). North African Cretaceous carbonate platform MILOVANOVIC, B. 1935. Contribution a la structure de la systems. Kluwer Academic Publishers, Dordrecht, 525 pp. couche externe des rudistes. Bulletin du Service Geologique -- and MASSE, J.-P. 2000. Synoptic guide to Lower Creta Royal de Yougoslavie, 4, 85-127. ceous rudist bivalves of Arabia. Middle East models of Juras NEWELL, N. D. 1965. Classification of the Bivalvia. American sic/Cretaceous systems. SEPM (Society fo r Sedimentary Museum Novitates, 2006, 1-25 . Geology) Special Publication, 69, 89-99. SLlSKOVIC, T. 1966. Katzeria hercegovinaesis n. gen. n. sp. STRUM, D. H. and PERKINS, B. F. 1975. Architecture of aus den obersenonischen Ablagerungen der Sudherzegowina. radiolitid rudists (Mollusca) shell-wall structures and its phy Conseil des Academies des Sciences et des Artes de la RSF de logenetic implications. 33rd Annual Proceedings of the Electron Yougoslavie, Bulletin Scientifique, A-12, 176-177. Microscopy Society ofAmerica, pp. 686-687. STANLEY, S. M. and HARDIE, 1. A. 1998. Secular oscilla TOUCAS, A. 1907. Etudes sur la classification et l'evolution tion in the carbonate mineralogy of reef-bulding and sedi des radiolitides: Agria et Praeradiolites. Memoires, Bulletin de ment -producing organisms driven by tectonically forced shifts la Societe Geologique de France, Paleontologie, 36 (14), 1-46 . in seawater chemistry. Palaeogeography, Palaeoclimatology, VI LARD ELL, O. and GILl, E. 2003. Quantitative study of a Palaeoecology, 144, 3-19. hippuritid rudist lithosome in a Santonian carbonate platform STEUBER, T. 1996. Stable isotope sclerochronology of rudist in the southern Central Pyrenees. Palaeogeography, Palaeocli bivalves: grov.1:h rates and Late Cretaceous seasonality. Geol matology, Palaeoecology, 200, 31-41. ogy, 24, 315-318. WEISSERT, H., LINI, A., FOLLMI, K. B. and KUHN, -- 1999. Cretaceous rudists of Boeotia, central Greece. Special O. 1998. Correlation of Early Cretaceous carbon isotope Papers in Palaeontology, 61, 229 pp. stratigraphy and platform drowning events: a possible link? -- 2002. Plate tectonic control on the evolution of Cretaceous Palaeogeography, Palaeoclimatology, Palaeoecology, 137, 189- platform carbonate production. Geology, 30, 259-262. 203. lanation of .bb«viatiorn; ,c..!, bar r