original scientific paper UDC 56:591 553.5:56 A STUDY OF THE MORPHOLOGICAL VARIABILITY OF RADIOLITES MARINII CAFFAU & PLENICAR (RADIOLITIDAE), LATE CENOMANIAN, KARST OF GORIZIA, ITALY Mauro CAFFAU & loanna PROTOPSALT! Dipartimento di Scienze Geologiche, Ambienîali e Marine deu'Universita di Trieste, IT-34127 Trieste, Via E. Weiss 2 E-mail: caffau@univ,triesi.e.it E-mail: protopsa@univ.trieste.it ABSTRACT The species Radiolites marinii Caffau & Plenicar is very abundant in the rudist assemblages of the limestone sequence of the area of "Archi", in the southeastern part of the Karst of Corizia, from the Upper Cenomanian age. The good preservation-state of several specimens found separately in the do/onstone allowed to analyse and describe in detail the external morphology of the shell of this species. The main feature of the external morphology is the difference between the upper and the lower part of the shell. Taking into account that this feature was observed in all adult specimens, transverse sections were made at the lower, middle (area where there is a change in the ornamentation) and upper part of the shell. Morphometrica! values regarding the shell area (Sa), the inner area of the shell (la), the external perimeter (Bp) and the internal perimeter dp) of the shell were obtained from each transverse section by image analysis. The analysis of these data indicated that the change in morphology could be due to a strong biological stress that markedly influenced the physiological trend of calcitic secretion for the building up of the shell in individuals of this species. Ke y words : rudists, morphological variability, Late Cenomaniana, image analysis INTRODUCTION Caffau and Plenicar (1991) described the rudist-rich assemblage of the limestone sequence of the locality of "Archi" in the southeastern part of the Karst of Corizia. The study of the rudist fauna brought to light the new species Radiolites marinii n.sp. {op. cit, pp. 268-269, Pi. 5, Figs. 1 -4; PI. 6, Figs. 1 -3). Fossil material was found in dolonstones where specimens were very well preserved. The optimal preservation state of rudist shells allowed to describe in detail the external morphological characters of all rudist specimens found, in particular those of the species R. marinii. The aims of this work are (i) to describe in detail the variations of the external ornamentation of the shell of the lower valve of R. marinii (ii) to analyse whether there is a relationship between the morphological vari­ability of the shell of this species and their life environ­ment by morphometrica! analysis (tii) to supply further stratigraphie and palaeoenvironmental information of this area of the carbonatic platform. Stratigraphie setting Moschenizza is a hill characterised by light and grey fossiliferous limestones and dolonstones. The sequence is divided in the following three units, from the most ancient to the most recent one: Maura CAFFA U & tonna PROTOFSALTl: A STUOV OF THE MORPHOLOGICA L VARSA8IUTY .... 181-2% 1. Packstone/grainstone 1,7.5 m thick) with rare "bouquets" of Praeradiolites fleuriausus (d'Orbigny), singly specimens of R. marinii and Radiolites radiosus d'Orbigny. in addition, abundant specimens of Chondrodonta joannae (Choffat) and Neithea fleuriausiana (d'Orbigny) are present. 2. Dolonstone (2.5 m thick) characterised by a rudist assemblage of many species, such as Radiolites carsicus Caffau & PleniCar, Radiolites presauvagesi communis Poisak, R. radiosus d'Orbigny, Eoradiolites zucchii Caf­fau & Plenicar, Eoradiolites adriaticus Caffau & Plenicar, P. flueuriausus, requieniids, C. Joanne and N. fleuriausi­ana. 3. Floatstone with a matrix of sifty bioclastic pack-stone (5 m thick) with scarce specimens of R. carsicus, P. flueuriausus and requieniids. The bottom of this sequence (unit 1) represents the appearance of the first communities of C. joannae and radioiitids that served as a rigid substratum for the sub­sequent generations of radioiitids and requieniids (unit 2}. in this second unit there is the major faunistic diver­sification of rudists. in unit 3 the rudist fauna progres­sively diminishes and disappears at the top of the se­quence. The rudist species P. flueuriausus, R. radiosus and requieniids are always present in all three intervals. in addition, the micropafaeontological content con­sists of Chysalidina gradata d'Orbigny, Nezzazata sim­plex Omara, Trochospira avnimelechi Hamaoui & Saint-Marc, Biconcava bentori Hamaoui & Saint-Marc, Num-. mofallotia apula Luperto Sinni, Cuneolina pavonia d'Orbigny and Nezzazatinella picardi (Henson). Because of the presence of the foraminifers C. gra­data and T. avnimelechi in addition to P. fleuriausus and C. joannae, the limestones of the sequence of "Archi" are assigned to the Upper Cenomanian age. Figs, la, b, c, d: Radiolites marinii. Ventral view (a): both radial hands, protruding and rounded in shape, are visible at the middle-upper part of the individual. The area between the radial bands is characterised by large lamae bent towards the bottom in the upper part of the individual, and by tiny lamellae in the lower part. x1. Dorsal view (b): the difference between the ornamentation of the lower and the upper part of the right valve is observed. View of posterior (c) and anterior (d) sides where the change of the ornamentation between the lower and the upper part of the valve is well visible, xl SI. 1a, b, c, d: Radiolites marinii. Prednja stran (a): Obe radialni progi, izbočene in okrogle oblike, sta vidni na prednjem zgornjem delu osebka. Površina med radialnimi progami ima značilne velike lamele, ukrivljene navzdol na zgornjem delu primerka in tanke lamele v spodnjem delu. xt. Zadnja stran (b): razlika v ornamenfaciji med spodnjim in zgornjim delom desne lupine. Zadnja (c) in prednja (d) stran z dobro vidnimi spremembami v ornamentaciji med spodnjim in zgornjim delom lupine. x1 Taphonomy of radioiitids and requiniids (Skelton & Giii, 1991). Ali the species of radioiitids are represented by elevator The rudist fauna consists of oligotypical assemblages ecological morphotypes. Small bouquets of specimens Maura CAFFAU ii loanna PROTOP5ALTI: A STUDY O f THE MORPHOLOGICAL VARIABILITY 281 -296 of P. fleuriausus are the only type of aggregation of ra­diolitids that is present in the sequence of "Archi". The requieniids are represented by large specimens, usually-located at the sides of the small "bouquets" of P. fleuriausus or in thin tabular lithosomes. The requieniids are factional dingers sensu Skelton & Giii (1991) and Gili etal. (1995). Bioturbations are a common feature of the preserva­tion state of most rudists found that, if present, can be observed in the upper part of the right valve. Therefore, and consistent with Philip (1972), it is possible that the lower part of the right valves was buried in the sedi­ment, whereas the upper part was out of the sediment. The lack of bioturbations in the lower part of the right valves could also be attributed to other factors, such as the sedimentation rate and the growing rate of the indi­viduals to avoid being buried in the sediment (Skelton ef a/., 1995). MATERIAL AN D METHOD The specimens of R. marinii studied in this work be­long to the collection of the Dipartirnento di Scienze Geoiogiche, Ambientali e Marine of the University of Trieste and include either adult or young specimens, in a whole, 21 specimens (16 adults and 5 young speci­mens) of R. marinii are studied in this work, with a total of 59 transverse sections. After an accurate observation of the external morphology of the right valves, an initial cut is made where a change in the ornamentation oc­curs (see description of the morphological variability). Afterwards, other two transverse sections are performed few centimetres below and above the initial cut. The images of these sections are acquired and proc­essed as follows; - Image acquisition: the acquisition is made in a personal computer by means of a CC D colour camera mounted on an optical mineralogicai microscope. The image is then digitised by means of an analogue-to­digital converter, i.e. Matrox Meteor, - image pre-processing and features extraction: the initial image shows 256 shades of grey in contrast with the background. The contrast is further enhanced through digital filters, thereby resulting in a final image of black objects against a white background. The format used for the images is 512 x 512 pixels. The whole sys­tem consists in an automatic programme (WinMorfo) that has been appropriately written in C language and Visual Basic running on a personal computer. The pro­gramme automatically extracts from each object the formal features that are considered to be characteristic, with precision levels comparable to manual or semi­automatic methods (Protopsalti, 1997), Fig. 2: Transverse section of a right valve of Radiolites marinii, where the measured area (Sa) (la) and pe­rimeter (Ep) (Ip) are indicated. Moreover, the structures of the anterior radial band (ab) and the posterior radial band (pb) are pointed out. Si. 2: Prečni prerez desne lupine vrste Radiolites marinii z označeno merjeno površino (Sa) (la) in perimetrom (Ep) (Ip). Označene so tudi strukture na prednji radialni progi (ab) in zadnji radialni progi (pb). The parameters ia, Sa, Ip and Ep (Fig. 2) are related to the biological functions of the specimens as previ­ously described by Cestari (1992), Reali (1992), Caffau & Pleničar (1994/95) and Caffau & Pleničar (1996). In detail, these parameters are: - Sa (mm2): shell area or surface of the mantle that is responsible for the incoming water flux and the entrance of nutrients in the inner cavity. - ia (mm2): area of the inner cavity that contains the organic tissues involved in the assimilation of nutrients. - Ep (mm): external perimeter that is in close cor­relation with the external development of the shell. It may change depending on the (kind of) interaction of the individual with the environment (i.e. the building up of protruding ribs in order to augment the surface of contact with the substratum) or with other individuals (i.e. in "bouquets" or other forms of aggregation). - Ip (mm): perimeter of the inner layer of the shell. The values of these parameters obtained for all the analysed specimens are plotted in dispersion diagrams (Fig. 3). The images of the transverse sections of the right valves of R. marinii are shown in Plates 1-7 and the morphometricai values are summarised in Table 1. Maur a CAFFAU t , tanj PROTOPSALTl: A STUDY O F THE MORPHOLOGICAL VARIABILITY ....281 -2 % SICLA fa (mm2) Sa (mm2)A1 0.979 0.965 A2 1 386 2.077 A3 2.137 3.670 B1 a 1.307 1.903 Bib 1.562 2.990 B2a 1.372 2.699 B2b 2.221 3.481 B3a 1.980 2.102 B3b 2.056 2.888 B3c 3.334 4.304 C I a 0.874 1.219 C2a 1.500 2.289 C3a 1.519 2.573 D1a 0.830 1.157 D2a 1.601 3.313 D3a 2.569 3965 Ela 0.635 1.058 E2a 0.762 2.394 F1a 1.015 1.860 F2a 1.049 3.274 F3a 1.781 3.874 G1 a 1.518 2.214 G2a 2.263 5.209 11a 1.606 1.970 12a 1.855 3.464 13a 2.084 3.647 11a 0.85I 1.168 12a 1.832 1.629 13a 1.943 2.525 Mia 0.585 1.590 M2a 1.193 2.270 M3a 1.305 2.436 Nl a 1.655 2.637 N2a 2.066 2.864 N3a 2.535 4.496 Ol a 0.594 1.604 02a 1.613 2.665 0 3 a 1.711 2.815 PI a 0.427 0.687 P2a 0.636 1.527 P3a 0.701 1.878 Ql a 1.346 2.158 Q2a 1.664 3.010 Q3a 2.991 3.508 Rl a 0.681 0.822 R2a 1.349 1.919 R3a 1.572 2.425 Sl a 1.184 1.544 S2a 1.936 1.833 S3a 2.118 3.145 Tl a 0.674 0.931 T2a 1.180 2.062 13 a 1.290 2.535 Vi a 0.558 1.443 V2a 1.117 2.303 V3a 1.663 2.824 Wl a 0.814 2.004 W2a 1.617 3.070 Ip (mm) 3.455 4.132 5.I59 4.121 4.516 4.306 5.305 4.950 5.065 6.379 3.275 4.346 4.300 3.234 4.432 5.575 2.763 3.101 3.572 3.659 4.864 4.282 9.190 4.564 4.845 5.100 3227 4.763 4.954 2.742 4.096 4.033 4.504 5.042 5.739 2.726 4.448 4.632 2.328 2.774 2.997 4.097 4.517 6.148 2.866 4.065 4.389 3.863 4.938 5.150 2.882 3.948 4.023 2,604 3.684 4.556 3.228 4.567 Ep (mm) 5.525 7.877 9.208 7.595 8.661 7.953 9.963 7.723 8.669 10.280 5.201 7.206 7.257 5.429 8.760 9.864 5.419 7.536 6.451 7.563 8.748 6.848 3.082 7.172 8.967 8.919 5.614 7.203 8.419 5.572 7.196 7.495 7.823 8.082 10.028 6.304 8.280 8.181 4.404 5.894 6.492 7.790 8.321 10.062 4.642 7.161 7.810 7.214 7.127 8.572 5.309 8.422 7.666 5.403 6.929 8.398 7.517 9.057 Tab. 1: Morphometrical values obtained from trans­verse sections corresponding to the upper (commisure), middle (ornamentation change) and lower parts of right valves of Radiolites marinii. la inner area (mm2), Sa shell area (mm2), ip inner pe­rimeter (mm), Ep external perimeter (mm). Tab. 1: Morfometrične vrednosti prečnih prerezov, ki ustrezajo zgornjim (komizure), srednjim (ornamenta­cijska sprememba) in spodnjim delom desnih lupin vrste Radiolites marinii. ia notranja površina (mm2), Sa površina lupine (mm2), Ip notranji perimeter (mm), Ep zunanji perimeter (mm). SYSTEMATIC PALAEONTOLOGY Order H! PPU RITO I DA Newell, 1965 Superfamily HiPPURITACEA Cray, 1848 Family RADiOLlTlDAE d'Orbigny, 1847 Subfamily RADiOLITiNAE d'Orbigny, 1847 Genus Radiolites Lamarck, 1848 Radiolites marinii CAFFAU & PLENtČAR, 1991 Figs.1 a-d; Pis. 1-7 Diagnosis: The right valve of R. marinii is conical in shape in young specimens (Pi. 1, Figs, la , b, c) and cylindro-conical in adults (PI. 1, Figs. 4a, b). The orna­mentation consists of transverse lamae with waving bor­ders and longitudinal rounded ribs. The lamae are less prominent at the bottom and become larger, more prominent and waved towards the top of the right valve. Two of the longitudinal ribs are larger than the others and correspond to the anterior and posterior radial bands. The internal structure is a mesh of polygonal cells that is more compact at the radial bands. The left valve is dome-like shaped and exhibits two flattened ribs that correspond to the anterior and poste­rior radial bands. The transverse section of the left valve shows a compact mesh of cells. External morphology: R. marinii exhibits a large morphological variability that is clearly observed in the ornamentation of different specimens of this species. Attached right valve: This valve is conical at the lower part and cylindrical at the upper part in adult specimens (Figstext 1a, b, c, d, PI. 2, Fig. 2), whereas it is markedly conical in shape with a width aperture in young individuals (PI. 1, Fig. 1). The length of these valves varies from 30 to 45 mm and the thickness of the shell is 2mm at the dorsal area and 3.5 mm at the ventral one. Maur o CAFFAU & toanna PROTOPSAJ.TI: A STUDY Of THE MORPHOLOGICAL VARIABILITY ..., MS-2 % 1° transverse section 2° transverse section 3° transverse section la (mm2) Ip(rom) Fig. 3: Shell area (Sa) vs inner area (la) (3 a, b, c) and external perimeter (Bp) vs inner perimeter dp) (3 d, e, f) correspondig to three transverse sections from the upper (commisure), middle (ornamentation change) and lower parts of right valves o/Raciiolites marin n. Regression values and dispersion coefficients are shown for each plot. SI. 3: Površina lupine (Sa) proti notranji površini (la) (3 a, b, c) in zunanji perimeter (Bp) proti notranjemu pe­rimetru (tp) (3 d, e, f), ki ustrezajo trem prečnim prerezom zgornjih (komizure), srednjih (omamentacijska sprememba) in spodnjih delov desnih lupin vrste Radioiites marinti. Regresijske vrednosti in disperzijski koeficienti so podani za vsak graf posebej. Maur o CAEFAU í» tonnna PROTOfSAlTt - A STLJOY O f THE MORPHOLOGICA L VARIABILITY .... 28 Í -OT& Ornamentation: The right valves of adult specimens always exhibit two different morphologies. The orna­mentation in the lower part of these valves consists of longitudinal ribs that are more or less prominent and robust among different specimens whereas in the upper part it is characterised by transverse and concentric la­mae (Figstext la , b, c, d, PI. 1, Figs. 4a, b). The ornamentation in young specimens is the same as present in the lower part of the adult right valves (PI. 1, Figs, la , b, Figs. 2a, b). Posterior and anterior sides (Figstext 1c, d); In adult specimens the ornamentation of these sides consists of concentric lamae and robust longitudinal ribs that are badly preserved due to the fact that these are the areas of adherence with other individuals. In detail, thin and delicate lamellae alternate with robust and longitudinal ribs in the lower part. The thin lamellae become robust and prominent lamae with waved borders in the upper part, where the longitudinal ribs are almost absent. Dorsal side (Figtext lb); The ligamental groove is hardly visible and the ornamentation is poorly defined. The lamae are robust and the longitudinal ribs are scarcely marked. However, the morphological differ­ence in the ornamentation between the lower and the upper part of this side is still evident in all specimens. Ventral side (Figtext la): From the lower part, the apex is cylindrical in shape, up to 15 mm long and 2 to 8 mm in diameter. Afterwards the shell becomes mark­edly conical. The ornamentation of the apex (Figtext 1a, PI. 1, Fig. 4) consists in longitudinal and tiny ribs inter­rupted by lamae that testify the presence of megacycles, sensu Cestari (1992). The number of megacycles varies from 4 to 7 according to the dimensions of the speci­mens. The border of the lamae between two megacycles is waved. The lamae are more protruding in the upper part than in the lower one. Also in the upper part of the shell, megacycles are hardly seen and actually they are hid­den by the well-developed lamae that are folded to­wards the bottom. The longitudinal ribs, which are in the lower part well visible, become hardly distinguish­able or even disappear in the upper part of the ventral side. The anterior radial band (ab in Figtext la , PL 2, Fig. 4) and posterior radial band (pb in Figtext 1a, Pi. 2, Fig. 4) form a deep furrow all along the right valve. A very well developed rib, cylindrical in shape, is found along the inner part of each furrow. Both radial bands are 2-3 mm wide at the commisure of the right valve (Figtext 1a). The radial bands are separated by an area with transverse lamellae. These lamellae, which are thin and very close to each other in the lower part, become more protruding and more folded towards the bottom in the middle-upper part of the valve. Free left valve (Figstext la, b, c, d, PL 2, Fig. 4): Convex valve, ornamented by very thin concentric growth lines and tiny radial costule that initiate in the cardinal area. In some well-preserved specimens, the border of the free valve can cover the lamae at the commisure of the right valve. Moreover, the left valve forms a roof-like structure that protrudes at the radial bands of the right valve. The thickness of the free valve is always less than 0.7 mm and the inner structure of the shell is compact. interna! characters (PL 2, Fig. 1): The section of the mean cavity is circular and exhibits two slight deeps at the radial bands. The ligamental ridge is prominent and robust with a rectangular shape, slightly enlarged to­wards the end. Shell structure (PI. 2, Fig. 1): (a) The inner layer, generally less than 0.5 mm thick, consists of only one row of prismatic cells, (b) The outer layer, formed by two different structures: the first, a mesh of polygonal cells that is located close to the inner layer, and the sec­ond that consists of parallel rows of cells that follow a waved trend in correspondence with the external ribs that ornament the right valve. The internal structure at the radial bands consists of a mesh of very small prismatic cells. The pseudopilar cor­responding to the anterior band is represented by a very pronounced sinus, whereas that of the posterior band consists of two sinuses. The latter are characterised by a dual structure, composed of lamellae and prismatic small cells. MEASUREMENTS: DISCUSSION Area! measurements: For the first and third trans­verse sections (Figs. 3a, c) there is a good correlation between the parameters ia and Sa, as shown by the re­spective dispersion coefficients (R2). In addition, for the same group of data, similar values of regression slopes can be observed. On the other hand, the data of the second transverse section (Fig. 3b) give a poor correla­tion between la and Sa and the regression slope ts dif­ferent from the former. Perimeter measurements: Regarding the data of the first and third sections (Figs. 3d, f), the values of the dis­persion coefficients (R2) show that there is a good corre­lation between the parameters Ip and Ep. There is, how­ever, a poor correlation of these parameters for the sec­ond transverse section (Fig. 3e). Still, the values of the regression slopes are similar. Mauro CAFfAU & Joanna FROTOPSAITS: A STUDY OF THE MORPHOLOGICAL VARIABSLiTY .... 2B1 -2 % FINAL CONSIDERATIONS AND CONCLUSIONS tures (reflected in the morphological parameters) and the external ornamentation of the shell. The observation of the morphology of this species and the results obtained by morphometries! analysis of 21 specimens led to the following considerations: -R.marinii is characterised by a clear change in the morphology of the shell ornamentation of the right valve of adult individuals. - Morphological parameters that are involved in biological functions of this species lose their good corre­lation where there is a change in shell ornamentation. Therefore, it is clear that the change in the ornamen­tation of the right valve represents a physiological re­sponse of the individual to an important environmental change (i.e. an enhanced rate of sedimentation or the fall of the individual from its physiological position). This response may be an abnormal secretion of calcite by the individual that alters some physiological struc- The considerable morphological variability of this species gives an idea of how difficult may be in some ca­ses to look for valid features for a proper use in taxonomy. Finally, according to the microfossil content and the fauna that is present in the sequence of "Archi11 it is pos­sible to attribute the species R. marinii to the Late Cenomanian. ACKNOWLEDGEMENTS We are most grateful to Prof. Mario Plenicar for his helpful suggestions and pleasant discussions on the work. We also would like to thank Cristiano Landucci for the development of the software WinMorfo for the image acquisition and for his useful co-operation in the data processing stage. ŠTUDIJA O MORFOLOŠK I VARIABILNOST I RADIOUTES MARINII CAFFA U & PLENIČAR (RADIOLSTIDAE), VIŠJI CENOMANIJ, GORIŠK I KRAS, ITALIJA Mauro CAFFAU & loanna PROTOPSALT1 Oddelek za geologijo, okoljske in morske vede Univerze v Trstu, IT-341 27 Trst, Via E. VVeiss 2 t-mail: caffau@univ.trieste.it E-mai!: protops3@univ.triesie.it POVZETEK V sukcesiji od apnencev do rudistov, pripadajočih višjemu cenomaniju z območja "Archi" na jugovzhodnem Goriškem Krasu, je vrsta Radio!ites marinii Caffau & Pieničar zelo dobro zastopana. Osebke te vrste zaznamujeta dve morfoiogiji ornamentacije zunanjih površin lupin, ki bistveno ločujeta spodnji del lupine od zgornjega. Za vse odrasle osebke so bili izdelani prečni prerezi v spodnjem (apikainem), srednjem (kjer je opazen prehod iz prve or­namentacije v drugo) in zgornjem delu (kornisura). Iz vsakega prečnega prereza sta avtorja dobila modometrične vrednosti o površini lupine (Saj, površini notranje votline lupine (ta), zunanjega (Ep) in notranjega (!p) obsega lupine. Analiza morfometričnih podatkov je pokazala, da so osebki pri prehodu iz ene ornamentacije v drugo doživeli močan biološki stres, ki je znatno vplival na normalno izločanje karbonatov. Ključne besede: rudisti, morfološka variabilnost, višji cenomanij Maur o CAFf AU ft loanna PROTOPSAIT1: A STUDY Of THE MORPHOLOGICAL VARIABILITY ..., 281-296 REFERENCES Caffau, M. & M. Pieničar (1991): Rudists fauna from Turonian deposits of the locality "Arc hi "/Mo see nice in the surroundings of Duino (Karst of Trieste). Razprave IV. Razreda SAZU, 32 (8), 259-315. Caffau, M. & M. PJeničar (1994/95): Preliminary bio­metrical analysis on three similar hippuritid species. Geologija 37 (38), 123-140. Caffau, M. & M. Pleničar (1996): Biometrical analysis on Biradiolites angulosas d'Orbigny in the stratigraphie sequence of the Bay of Sistiana (Trieste Karst-italy). Raz­prave IV, Razreda SAZU, 37 (5), 99-117. Cestarí, R. (1992): Biometrical analysis on gorjanovicias and other radiolitids (Radiolitidae, Hippuritoida). Ge­ológica Romana, 28, 1-25. Gilí, E., J. P. Masse & P. W. Skelton (1995): Rudists as gregarious sediment-dwellers, not reef-buiders, on Cre­taceous carbonate platforms. Palaeogeogr. Palaeoclima­tol. Palaeoecol. 118, 245-267. Philip, J. (1972): Palaéoécologie des formations a rudi­stes du Crétacé supérieur-l'exemple du Sud-Est de la France. Palaeogeogr. Palaeoclimatol. Palaeoecol., 12, 205-222. Protopsaiti, J. (1997): Applicazione di un método auto­mático per l'estrazione di parameîri morfometrici da clash per una caratterizzazione di sedimentí marini e costieri antartici in ottica paleoambientale. Tesi di dot­torato inédita pp - 104. Reaíí, S. (1992): Preliminary morphometric analysis for Hippuritids taxonomy. Geológica Romana 28, 91-103. Skelton, P. W. & E. Gilí (1991): Palaeocological clas­sification of rudist morphotypes.- In 1st Int. Conf. Rudist. Beograd, 1988 Serb. Geol. Soc. Spec. Publ., 2, 71-86 (reprint). Skelton, P. W., E. Gilí, E. Vicens & A. Obrador (1995): The growth fabric of gregarious rudist elevators (hippuritids) in a Santonian carbonate platform in the southern Central Pyrenees. Palaeogeogr. Palaeoclimatol. Palaeoecol. 119, 107-126. PLATE 1 Figs. 1 a, b, c: Radiolites marinii. View of the ventral side (a), posterior side (b) and the commisure (c) of the right valve in which there is no change in the morphology between the lower and the upper part of the valve. x1 Figs. 2 a, b, c: Radiolites marinii. View of the ventral side (a), posterior side (b) and the commisure (c) of the right valve. The change in the morphology between the lower and the upper part of the valve is evident in this specimen. x1 Figs. 3 a, b: Radiolites marinii. View of the ventral side (a) and posterior side (b) of a complete specimen with both valves. x1 Figs. 4 a, b: Radiolites marinii. View of the ventral side (a) and posterior side (b) of the right valve in which the difference in the morphology between the lower and the upper part is clearly evident, xt TABLA 1 SI. 1 a, b, c: Radiolites marinii. Prednja stran (a), zadnja stran (b) in komizure (c) desne lupine, kjer ni vidnih morfoloških sprememb med spodnjim in zgornjim delom lupine. x1 SI. 2 a, b, c: Radiolites marinii. Prednja stran (a), zadnja stran (b) in komizure (c) desne lupine. Morfološke spremembe med spodnjim in zgornjim delom lupine pri tej vrsti so vidne. x1 SI. 3 a, b: Radiolites marinii, Prednja stran (a) in zadnja stran (b) celotnega osebka z obema lupinama. x1 SI. 4 a, b: Radiolites marinii. Prednja stran (a) in zadnja stran (b) desne lupine, kjer so dobro vidne morfološke spremembe med spodnjim in zgornjim delom lupine. x1 PLATE 2 Fig. 1: Radiolites marinii. Thin transverse section of the right valve. Structure of polygonal cells that are smaller at the radial bands pb and ab. x3.5 Fig. 2: Radiolites marinii. View of the ventral side of the right valve in which the difference in the morphology between the lower and the upper part is clearly evi­dent. xJ Fig. 3 : Radiolites marinii. Wew of the ventral side of the right valve. x1 Fig. 4; Radiolites marinii. View of the ventral side of the left valve and part of the right valve in which the lamae and the radial bands are well preserved. Note the good preservation state of the area of contact between the right and the left valves, v 7 Mauro CAWAU S, Icrarera PROTOPSAITI: A STUDY OF THE MORPHOLOGICAL VARIABILITY .... 281-236 TABLA 2 SI. 1: Radiolites marinH. Tanek prečni prerez desne lupine. Struktura poligonalnih celic, ki so manjše pri radialnih progah pb in ab. x3.5 SI. 2: Radiolites marinii. Prednja stran desne lupine, kjer so dobro vidne morfološke razlike med spodnjim in zgornjim delom lupine. x1 Si. 3: Radiolites marinii. Prednja stran desne lupine. x1 Si. 4: Radiolites marinii. Prednja stran leve lupine in del desne lupine, pri kateri so lamae in radialne proge dobro ohranjene. Opazna je visoka stopnja ohranjeno­sti stične površine med desno in levo lupino. x1 PLATE 3 Figs. A1-B3c: Radiolites marinii Transverse section of the right valves subjected to morphometrical analysis. Scale bar ~ 1cm. TABLA 3 Si. A 1-B3c: Radiolites marinii Prečni prerezi desnih lupin, ki so bili morfometrično obdelani. Merilo -1cm. PLATE 4 Figs. C1a-F3a: Radiolites marinii. Transverse section of the right valves subjected to morphometrical analysis. Scale bar ss 1cm. TABLA 4 SI. C1a-F3a: Radiolites mar/ni/. Prečni prerezi desnih lupin, ki so bili morfometrično obdelani. Merilo = Icm. PLATES Figs. Gla-M3a: Radiolites marinii. Transverse section of the right valves subjected to morphometrical analysis. Scale bar = 1cm. TABLA 5 SI. G1a-M3a: Radiolites marinii Prečni prerezi desnih lupin, ki so bili morfometrično obdelani. Merilo -1cm. PLATE 6 Figs. N1a-Q3a: Radiolites marinii. Transverse section of the right valves subjected to morphometrical analysis. Scale bar = 1cm. TABLA 6 Si N1a-Q3a: Radiolites marinii. Prečni prerezi desnih lupin, ki so bili morfometrično obdelani. Merilo = 1cm. PLATE 7 Figs. R1a-W2a: Radiolites marinii Transverse section of the right valves subjected to morphometrical analysis. Scale bar = 1cm. TABLA 7 SI. R1a-W2a: Radiolites marinii. Prečni prerezi desnih lupin, ki so bili morfometrično obdelani. Merilo ~ Icm. PLATE 3 / TABLA 3 ANNALES • Ser. hisi. nat. • 9 • 1999 • 2 (17) Maure CAFFAU S, loaim» I'ROTO PS AIT!: A STUDY OF THE MORPHOLOGICAL VARIABILITY .... 281-296 291 ANNALES • Ser. hist. nat. • 9 - 1999 • 2 (17) Mamo CAF'FAU & Icranna PROTOPSAi.Tl: A STUDY O f T HE MORPHOLOGICAL VARIABILITY ..., 2SS-296 PLATE 3 / TABLA 3 292 Manto CAFFAlj & !Banna PROTOÍ'SALTi: A STUDY OF THE MORPHOLOGICAL VARIABILITY 281-2 W • m ™ L3a .... •• , .« " iVlla M2a M3a PLATE 3 / TABLA 3 ANNALES • Ser. hist. nat. • 9 - 1999 • 2 (17) Mauro CAFFAU & loanra PROTOPSALTJ: A STUDY OF THE MORPHOLOGICAL VARIABILITY .... 281-2 % v h . v.. : •wwllSiliSll N2a N3a N1a PLATE 3 / TABLA 3 295 ANNALES • Ser. hist. nat. • 9 - 1999 • 2 (17) Mai/ro CAFFAU & loanna PKOTOPSALTI: A STUDY O F THE MORPHOLOGICA L VARIABILITY ..., 281-29 6 W2a PLATE 3 / TABLA 3 296