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Zoologisch-Botanische Datenbank/Zoological-Botanical Database

Digitale Literatur/Digital Literature

Zeitschrift/Journal: Jahrbuch der Geologischen Bundesanstalt

Jahr/Year: 1994

Band/Volume: 137

Autor(en)/Author(s): Gradinaru Eugen, Barbulescu Aurelia

Artikel/Article: Upper Jurassic Brachiopod Faunas of Central and North Dobrogea (Romania): Biostratigraphy, Paleoecology and Paleobiogeography 43-84 ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at r~JJA[H][RlBlUJC[H] [})[E[R G[EO[lOG~SC[H][EN lBlUJN[})[ESANSlrA[llr ~ LJb. Geol.B.-A. I 155N0016-7800 II Band137 II Heft 1 II 5.43-84 II Wien,Juni 1994 I

Upper Jurassic Brachiopod Faunas of Central and North Dobrogea (Romania): Biostratigraphy, Paleoecology and Paleobiogeography

EUGEN GRÄOINARU & AURELIA BÄRBULESGU*)

14 Text-Figures, 1 Table and 4 Plates

Rumänien Dobrudscha Brachiopoden Oberjura Oxford Kimmeridge Biostratigraphie Patäoökologie Paläobiogeographie Taxonomie

To celebrate 125 years from the publication of the classic monograph "Grundlinien zur Geographie und Geologie der Dobrudscha" written by the Austrian geologist KARL FERDINAND PETERS (1825-1881)

Contents Zusammenfassung 44 Abstract ...... 44 1. PETERS' vs. WILSER'S Statements on the Dobrogean Upper Jurassic Geology: The Brachiopod Distribution Pattern as a Test Case 44 2. Geologic Setting and Stratigraphic Occurrence of the Central and North Dobrogean Upper Jurassic Brachiopod Faunas: A Highly Unbalanced Distribution Pattern 45 3. Central Dobrogean Upper Jurassic Brachiopod Faunas 48 3.1. Casimcea Formation (Oxfordian-Lower Kimmeridgian): An Extensive Brachiopod Occurrence in a Shallow-Water Carbonate Platform...... 48 3.1.1. Visterna Bioconstructed Spongalgal Series...... 48 3.1.2. Cekirgea Stromatolitic Algal Series 50 3.1.3. Topalu Bioconstructed Coralgal Series 52 4. North Dobrogean Upper Jurassic Brachiopod Faunas 53 4.1. Cärjelari Formation - Sfänta Facies (Oxfordian-Lower Kimmeridgian): A Restricted Brachiopod Occurrence in a Transtensional Basin 53 4.2. Carabair Limestone (Middle Oxfordian): A Scattered Brachiopod Occurrence in a Deep-Water Carbonate Basin 55 5. PaleoecologicAnalysis 56 5.1. Areal Distribution Pattern...... 56 5.2. Diversity and Density 59 5.3. Size-Frequency Distribution 62 5.4. Preservation State 63 5.5. Brachiopod Morphology in Response to Environmental Factors 64 5.6. Brachiopod Relationships with Other Benthic Organisms 65 6. Paleobiogeographic Analysis 66 7. Systematic Paleontology 69 Acknowledgements 73 Plates ...... 74 References ...... 82

*) Authors' address: Dr. EUGENGRÄDINARU,Dr. AURELIABÄRBULESCU,University of Bucharest, Faculty of Geology and Geophysics, Department of Geology and Paleontology, Blvd. Bälcescu nr. 1, Bucharest, RO-70111, Romania.

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Oberjurassische Brachiopodenfaunen der zentralen und nördlichen Dobrudscha (Rumänien): Biostratigraphie, Paläoökologie und Paläobiogeographie Zusammenfassung Während in den Flachwasserkarbonaten der zentralen Dobrudscha reiche Brachiopodenfaunen des Mitteloxford-Kimmeridge zu finden sind (ca. 50 Arten aus 11 Familien), kommen in den resedimentierten Flachwasserkarbonaten oder in den Tiefwasserkarbonaten der nördlichen Dobrudscha Brachiopoden nur sehr selten vor (nur 7 Arten aus 5 Familien wurden bisher registriert). In der zentralen Dobrudscha treten in der Casimcea-Formation drei umfangreichere, brachiopodenführende, biogene Karbonatserien auf, die Visterna-Schwamm-Algen-Serie, die Cekirgea-Stromatolithen-Serie and die Topalu-Korallen-Algen-Serie, jede mit ausgeprägten, im wesentlichen autochthonen Brachiopodengemeinschaften, die Unterschiede in Wassertiefe und -durchbewegung anzeigen. In der nördlichen Dobrudscha war die markante Verarmung der Brachiopodenfaunen entweder auf tektonisch bedingte, sehr begrenzte, kurzzeitige Flachwasserkarbonat-Sedimentation im Peceneaga-Camena-Zerrungsbecken, wo die Cärjelari-Formation auftritt, zurückzuführen oder auf eine Tiefwasser-Schlamm-Sedimentation, wie im Fall der sehr ausgedünnten Brachiopodenfauna des Carabair-Kalks. Verschiedene paläoökologisch-taphonomische Aspekte, umweltbedingte Homöomorphie und die Beziehungen der oberjurassischen Brachiopo- denfaunen der Dobrudscha mit anderen benthischen Organismen wurden untersucht. Paleobiogeographisch gehören alle oberjurassischen Brachiopodenfaunen der Dobrudscha zum submediterranen Bereich des Jura. Eine neue Art, Dorsoplicathyris petersi n.sp., wird beschrieben; die taxonomische Stellung von Ptacothyris carsiensis (SIMIONESGU)wird revidiert.

Abstract While plentiful Middle Oxfordian-Lower Kimmeridgian brachiopod faunas are to be found in the shallow-water carbonate platform rocks of Central Dobrogea, where around 50 species, included in 11 families, have been registered, very scarce coeval brachiopod faunas occur in the resedimented shallow-water and basinal carbonate rocks of North Dobrogea, where only 7 species, included in 5 families, have been registered. In Central DObrogea, the Casimcea Formation displays three major brachiopod-bearing biogenous carbonate facies series, viz. Vis t ern aBi 0- con s t rue ted S p 0 n g a I g a I Se r i es, Ce kir g e aSt rom at 0 lit ic A I g a I Se r i e s and To p a lu Bio con s t rue ted Cor a I g a I Se r i es, each of them bearing distinct, essentially autochthonous brachiopod paleocommunities, primarily reflecting differences in water depth and energy levels. In North Dobrogea, the marked impoverishment of brachiopod faunas was related either to tectonically-stressed and very limited, short-lasting shallow-water carbonate sedimentation episodes in the Peceneaga-Camena transtensional basin, where the allochthonous brachiopod assemblage from the Cärjelari Formation is to be found, or to a deep-water muddy sedimentation for the very scattered brachiopod faunule from the Carabair Limestone. Various paleoecologic-taphonomic aspects, as well as the environmentally-induced homeomorphy and relationships of the Dobrogean Upper Jurassic brachiopod faunas with other benthic organisms have been examined. Paleobiogeographically, all the Upper Jurassic brachiopod faunas from Dobrogea belonged to the Sub-Mediterranean (Jura) realm. A new species, Dorsoplicathyris petersi n.sp., is described, and the taxonomic treatment of Placothyris carsiensis (SIMIONESGU)is revised.

1. PETERS'vs. WILSER'SStatements on the Dobrogean Upper Jurassic Geology: The Brachiopod Distribution Pattern as a Test Case

Among the Upper Jurassic faunas of Dobrogea, the bra- gions, obviously with negative implications for their asser- chiopods represent one of the best documented groups, tions when referring to the Dobrogean Jurassic geology. although unevenly distributed on this territory. Nowadays the origin of WILSER'S mis-statements is eas- As early as 1867 PETERSrecorded the presence of the ily to be explained. Upper Jurassic rocks and collected brachiopods in all the Firstly, WILSER completely ignored the peceneaga- areas where the Jurassic System is to be found in Dobro- Camena Fault and its significance for the Dobrogean geo- gea. Furthermore, according to our present knowledge logy, although several years before MRAZEC(1912) and MA- concerning the Dobrogean Upper Jurassic geology, it is COVEl (1912) had clearly indicated that the above-men- worthwhile emphasizing the high value of most of PETERS' tioned fault bounded two distinct Dobrogean sectors observations and opinions. showing very different geological evolutions and tectonic Unfortunately, ARKELL'S famous synthesis (1956:189) on regimes, i.e. a "pre-Balkan" platform southwards and a worldwide Jurassic geology completely ignored PETERS' "Variscan-Cimmerian" folded belt northwards, respect- valuable monograph on the Dobrogean geology and paid ively. On the contrary, WILSER overestimated the impor- attention only to the very uninspired account made by tance of the "Linie H'ir:;;ova - Constanza" by which he artifi- WILSER (1928). The latter had failed in synthesizing and cially divided the Dobrogean territory into two distinct correctly interpreting the disparate and reduced, often parts: a northern one, the so-called "Grundgebirge", contradictory, data of the relevant geological literature. grouping all the deformed rocks of both North and Central Therefore, in spite of the field evidence, WILSER(1928: 178) Dobrogea, older than the Late Jurassic, and a southern reported that in Dobrogea gently undulated Upper Juras- one, the so-called "Deckgebirge" , grouping the slightly sic deposits rest directly upon sharply folded Triassic de- deformed Late Jurassic and much younger rocks of the posits. Thanks to ARKELL'S authority, WILSER'S highly falla- "pre-Balkan" platform. cious picture on the Dobrogean Upper Jurassic geology It is true, however, that in adopting such a position, was accredited and acquired wider circulation. HÖLDER WILSERwas greatly influenced by MURGOCI(1915), who un- (1964:480) also promoted WILSER'S account. Quite re- expectedly minimalized the importance of the Pecenea- cently, DEWEYet al. (1973: Text-Fig. 7) have used ARKELL'S ga-Camena Fault, in separating very dissimilar tectono- synthesis, as only reference work for Dobrogea, in a well- stratigraphic terrains, Central-South and North Dobrogea, known plate tectonics essay on the Mediterranean re- respectively.

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Secondly, in the 1920s a major stepback occurred in the ältesten und bedeutendsten Cebirgsgrate der Meditermnregion Europas knowledge of the North Dobrogean Jurassic System as lIuch für den oberen jum die Rolle eines Scbeiderückens gespielt hilbe, ~nd compared with PETERS'monograph.On the one hand, the dass seine südwest/icbe Seite nicbt nur den bracbiopodenre/chen KlIlkbrl- dungen der mittleren Donlluländer (..Stmmberger Scbicbten" u.s. w.) presence of the Lower and Middle Jurassic in North Do- sondern lIuch Ablagerungen offin stlll/d, die mit gleichzeitigen Absätzen brogea, as it was shown by PETERS,has not been confir- im Nordwesten der Alpen eine grosse Abnlicbkeit bllben ..... med, with good reason, by REDLICH(1896) and POMPECKJ Although PETERS'opinions on the paleobiogeographic (1897). On the other hand, only doubtful Lower Jurassic relationships of the Central and North Dobrogean sectors rocks were inferred to exist by SIMIONESCU(1927). Lastly, as during the Late Jurassic times are now obsolete, his em- far as the Upper Jurassic is concerned, in spite of PETERS' pirical but intuitive picture upon the areal distribution and expectations (1867: 189) the later field-works failed to iden- facies differences of the Upper Jurassic deposits on the tify the outcrop area of the so-called "Planulaten-Kalk- Dobrogean territory, is, however, of a remarkable value stein vom Kara-bair", which could have been a very im- even after 125 years, being mostly confirmed by the pre- portant key in outlining the differences between the North sent data. Since the Peceneaga-Camena Fault was identi- and Central Dobrogean Jurassic geology. Besides, the fied much later, he could not realize at the time that the structural position of the Upper Jurassic deposits of the Jurassic paleogeography on the Dobrogean territories had Cärjelari region was not clearly established yet (SIMIONES- a strong tectonic control. However this does not diminish cu, 1911). Thus, no objective elements existed at that time in any way the high value of PETERS'pioneering work. to contradistinguish the Jurassic System of North Dobro- The differing aspects of the Upper Jurassic deposits in gea from that of Central Dobrogea, for which much pro- the two Dobrogean sectors, lying north and south of the gress was achieved in the meantime thanks to the basic Peceneaga-Camena Fault, respectively, are correspond- studies carried out by SIMIONESCU(1907,1910 a-b). ingly reflected also at the level of the fossil organism pa- That is why WILSER (1928:Tab. II), to whom the strati- leocommunities, as PETERS(1867) had already recog- graphic columns of the Central and North Dobrogean sec- nized. One ofthe most significant differences is illustrated tors seemed to be complementary owing to the foregoing by the highly unbalanced distribution of the Upper Juras- outlined circumstances, wrongly extended the Upper sic brachiopod faunas on the Dobrogean territory. Where- Jurassic deposits of Central Dobrogea over the Triassic as rich and very diversified Upper Jurassic brachiopod deposits of North Dobrogea. faunas are to be found in Central Dobrogea, very reduced PETERS'monograph, in spite of its imperfections, pro- coeval brachiopod faunas occur in North Dobrogea. vided a much more accurate picture of the Dobrogean Up- The field-works carried out in Dobrogea in the last de- per Jurassic geology than the one sketched by WILSER. cades allowed us or other geologists to collect rich and Had ARKELL(1956) relied on PETERS'monograph, much of varied Upper Jurassic brachiopod faunas, especially from his unfounded digressions upon the Cimmerian orogeny in Central Dobrogea. The study of these materials afforded a North Dobrogea, and the possible correlations with the more complete knowledge on the areal and stratigraphic Crimea, could have been avoided. distribution patterns of the different taxa, as well as on the First of all, PETERS(1867:177) had clearly stated that paleoecologic relationships of the different brachiopod there were no direct relationships between the Upper assemblages with the differing depositional environ- Jurassic deposits of Central Dobrogea and the Triassic ments, and finally much insight into the paleobiogeo- deposits of North Dobrogea. graphic interpretations. Although much taxonomic work is ..... Die ganze Trias, so wie auch Alles, was ich vom Lias und still to be done, the present study provides a measure of Mittel-jura im Lande vorfand, ist auf den nördlichen, gebirgigen Theil the advance made in recent times in the knowledge of the desselben bescbränkt. Südlicb von dem grossen Walle aus grünen Scbiefern beginl/t eine andere Natur. Bedeutende Aufbrücbe gibt es bier nicbt mebr; Dobrogean Upper Jurassic brachiopod faunas. mit den Triasscbicbten sind aucb die ibnen zugebörigen Massengesteine Therefore, the purpose of the present paper is two-fold: fern geblieben. Der obere jura bat sicb ebnend über die Scbollenfläcbe firstly, to demonstrate that the distribution pattern of the jener Schiefer gebreitet ..... Upper Jurassic brachiopod faunas on the Dobrogean ter- Moreover, PETERS(1867:178), who had the opportunity, ritory was highly dependent on the Late Jurassic paleo- unlike the subsequent researchers, to examine in the field geography; secondly, to reveal that both areal and strati- the Upper Jurassic deposits of both Central and North graphic distribution patterns of these faunas have been Dobrogea, had recognized very early that these deposits clearly connected with the local changing environmental display very different development patterns in the two Do- factors. brogean sectors: Our paper is dedicated to the memory of the distin- ..... Ein kleiner osteuropäiscber Bezirk vereinigt somit Tjpen in guished Austrian geologist Karl Ferdinand PETERS sich, die in Mitteleuropa nur an weit auseinander liegenden Punkten (1825-1881) for his great contribution to the knowledge of eil t wickelt sind ...... Sie bezieben sich ausschließlicb auf das Tafelland der mittleren the Dobrogean Jurassic geology and for the first record of und südlichen Dobrudscba, d.h. aufdie südlicb von dem grossen Walle aus Upper Jurassic brachiopod faunas in all the Dobrogean grünen Schiefern gelegenen Strecken. - Nördlicb davon hat die einzige geological units. bisbel' nllcbgewiesene Ablagerung von oberem jura einen lInderen Cbarllk- tel'. Am Kart/-bllir, der äussersten Crundgebirgsmllsse, die der Dunllvez umkrümmt, liegt unter der mäcbtigen Lössdecke ein scbwärzlicb oder bräunlicbgrlluer Kalkstein mit Planuillten und einigen lInderen Resten, 2. Geologic Setting deren Ausseben IIn den Mosklluer jura erinnert. Sebr interessllnt wäre es, and Stratigraphic Occurrence wenn künftige Forschungen erweisen würden, dass diese Scbicbte bier wirklicb eine Art von Vermittelung zwiscben der karpatbiscben Fllcies, of the Central and North Dobrogean prägnllnten Formen des südlicben (llusseralpinen) MitteleuroPlIs und den Upper Jurassic Brachiopod Faunas: in so vie/fllcber Hinsicbt eigentbümlicbenjuragebilden des Inneren von Russillnd berstelle. - DermIllen ist nur dlls eine sicber, dllss sie durcb ibre A Highly Unbalanced Distribution Pattern Cesteinsbescbllffenbeit von gleicbzeitigen Ablagerungen in der mittleren und südlicben Dobrudscbll, die dergleichen west/iche Beziebungen deut/icb The Dobrogea province lies in the southeastern part of gen/mg verratben, auffllllend verscbieden ist. Es scbeint demnacb, dass die Romania, between the lower course of the Danube and the Cebirgsmllsse der nördlichen Dobrudschllllls kleiner Oberrest eines der Black Sea coast (Text-Fig. 1).

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EEP- East EuropeanPlatform POD- Pre-Dobrogean Depression NOD- ~rth Dobrogean Orogen ITIID Mäcin Unit ~ Niculitel Unit l223 Tulcea Unit Moesian Platform CDS-Central Oobrogean Sector SOS-South Oobrogean Sector

SGF-Sf.Gheorghe Fault PCF-Peceneaga-Camena Faul COF- Capidava-Ovidiu Fault • borehole ,/15/ bathymetric contour

o 10 20 30 40 SOkm I +---1---' I I

Text-Fig. 1. Geological sketch map showing the surface (outcropping areas are hatched by closely-spaced thick-lines) and subsurface (boreholes) distribution pattern of Jurassic rocks on the Dobrogean territory and adjoining areas, and their stratigraphic relationships with the underlying rocks. Inset map shows the position of Dobrogean sectors within the major geological structure of Romania.

During the Jurassic, the Dobrogean territory was largely parts, corresponding to the actual Central and South 00- covered by seas. At present, the corresponding deposits brogean sectors, respectively. are only partially preserved in all the three geological sec- In the Central Dobrogean sector, the uppermost Middle tors of Dobrogea (Text-Fig. 1). All these sectors, showing Jurassic and Upper Jurassic shallow-water epicontinen- basically different tectono-sedimentary developments in tal deposits, displaying a very large facial complexity, are most periods, are tectonically bounded by major deep- widely outcropping and thus well-studied (SIMIONESCU, seated, NW-SE trending faults, the geodynamics of which 1910a; BÄRBULESCU,1974; CHIRIAC et aI., 1977; DRÄGÄ- strongly influenced the Dobrogean Jurassic paleogeo- NESCU,1976, 1985). The most important occurrences of graphy. the Jurassic deposits are limited to three main NW-SE It was especially the Peceneaga-Camena Fault which trending zones (Text-Fig. 1): Här~ova- Topalu-Bältäge~ti separated two distinct Jurassic sedimentary realms, Zone in the west, Casimcea Zone in the middle-east, and namely, a shallow-water siliciclastic/carbonate platform Doroban~u-Ovidiu Zone in the south-east. The Jurassic southwards, occupying the areas of the Central and South stratigraphic column starts with uppermost Bathonian- Dobrogean sectors, and at least two major basins of very Lower Callovian terrigenous calcaro-detrital deposits dynamic sedimentation situated northwards in the area of (Tichile~ti Formation), directly overlying the Vendian- the North Dobrogean sector. Lower Cambrian Green Schist Series of the epi-Baikal- The Capidava-Ovidiu Fault dissected the Dobrogean ian Moesian Platform-composite basement, and con- Jurassic siliciclastic/carbonate platform into two distinct tinues upwards with the Upper Callovian calcarenitic

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crinoidallimestones (Gura Dobrogei Formation) and the lovian brachiopod fauna is associated with the terrigen- most impressive Oxfordian-Lower Kimmeridgian bioac- ous calcaro-detrital sequence of the Tichile~ti Formation cumulated to bioconstructed limestones (Casimcea (BÄRBULESCU,unpubl.data). After an interval of interrup- Formation). tion during the Middle and Late Callovian and partially In the sunk South Dobrogean sector, the uppermost during the Early Oxfordian, owing to some stratigraphic Middle and Upper Jurassic deposits, a thick pile of dolo- gaps or to unfavourable facial conditions for their deve- mites and limestones, more than 400 m thick, were lopment, the brachiopod faunas have had a spectacular studied only by drillings (CHIRIACet aI., 1977; IORDANet aI., development beginning with the Middle Oxfordian, but 1987 a-b). and they exhibit a lithostratigraphic sequence reaching a maximum diversity and abundance during Late mostly comparable to that in the Central Dobrogean Oxfordian to Early Kimmeridgian times. Their develop- sector. ment was linked especially to the Casimcea Formation In the North Dobrogean sector, characterized by impor- bioaccumulated and bioconstructed calcareous facies tant Cimmerian to mid-Cretaceous folding and thrusting bearing stromatoliths, sponges and corals. Towards the processes, the Jurassic deposits are at present to be end of the Early Kimmeridgian the brachiopods, alongside found in the innermost part of the Macin Unit, and, on other macrofossils, disappeared from Central Dobrogea much larger surfaces, in the Tulcea Unit, respectively owing to a major regional regression. (GRÄDINARU,1981, 1984, 1988). In the first unit, it is the In the North Dobrogean sector, the Jurassic brachiopod Jurassic Carjelari-Camena Outcrop Belt which represents faunas have had a meagre development, both in the Carje- the topmost part of the Lower Mesozoic sedimentary lari-Camena Outcrop Belt and in the Tulcea Unit. In the cover of the Macin Unit and borders the peceneaga- first area their occurrence is limited only to the Upper Ox- Camena Fault immediately in its northern side. The strati- fordian-Lower Kimmeridgian biodetrital calcareous depo- graphic column includes in the basal part Middle Jurassic sits included in the Sfanta Facies of the Cärjelari terrigenous turbidites (Aiorman Formation), disconform- Formation. In the easternmost part of the Tulcea Unit, a ably overlain by a lot of different Upper Jurassic deposits, brachiopod faunule was yielded by the Middle Oxfordian of both shallow-water (Carjelari Formation) and deep-wa- pelagic cherty limestones (Carabair Limestone). ter facies (Ba~punar Formation). The latter, which are lat- Thus, the foregoing outlined imbalance is obscured for erally interfingering with rhyolitic volcanic rocks, are the Dobrogean Middle Jurassic brachiopod faunas, as topped by spilitic rocks. The Jurassic sedimentary rocks these are completely lacking in North Dobrogea, while and bimodal volcanics of the Carjelari-Camena Outcrop clear-cut for the Upper Jurassic brachiopod faunas for Belt characterized a very dynamic basin genetically linked which the available data leave abundant scope for a with the transtensile tectonic regime of the Peceneaga- thoroughgoing analysis of faunistic composition. That is Camena Fault during Middle to Late Jurassic times. why, only the Upper Jurassic faunas will be taken into ac- The Lower Mesozoic sedimentary cover of the Tulcea count in the present paper. For the Central Dobrogean Unit includes Jurassic rocks which were deposited in an sector, where the Upper Jurassic brachiopod faunas are ensialic deep-water basin. Lower Jurassic terrigenous, largely occurring, there were selected only the brachiopod mid-fan and outer-fan turbidites (N a I ban t Fan) and he- faunas delivered by the bioaccumulated and the interca- mipelagites (Po~ta Sandstone) are to be found in the lated bioconstructed limestones of the Oxfordian-Lower western part, whereas Middle Jurassic terrigenous, mid- Kimmeridgian Casimcea Formation which are biostrati- fan turbidites (D una v ä ~u Fan) and Middle Oxfordian graphically well-constrained by coeval ammonoid faunas. pelagic crinoidal and cherty limestones (Carabair These sequences are depositionally restrained to the Limestone) are outcropping in the easternmost part of the Har:?ova- Topalu area (along the Danube cliff) and to the Tulcea Unit. Visterna and Casimcea valleys, viz. to the western and All the Dobrogean sectors are downplunging eastwards middle-eastern areas of Central Dobrogea (Text-Fig. 2). into the subsurface of the continental shelf of the Black For North Dobrogea, the coeval brachiopod faunas from Sea, where several boreholes crossed a very thick Juras- the Carjelari and Dunava~u de Jos area will be considered sic sequence, somewhat very differing facially from those (Text-Fig. 3). of the Dobrogean land (PETROMAR, unpubl.data). The first mentions on the Dobrogean Upper Jurassic Lastly, northwards the North Dobrogean sector is in tec- brachiopod faunas date down to the 19th century (PETERS, tonic contact, along the Sf. Gheorghe Fault, with the Pre- 1867; POMPECKJ,1897; ANASTASIU,1898). More numerous Dobrogean Depression (VISARION, SÄNDULESCUet aI., data were provided later by ANASTASIU(1903,1907), MACO- 1990), where very thick Lower (?) to Middle Jurassic ter- VEl (1907), SIMIONESCU(1910 a-b). PATRULIUS& ORGHIDAN rigenous and Upper Jurassic carbonate sequences were (1964), PAJAUD & PATRULIUS(1964), BÄRBULESCU(1974, crossed by boreholes (SLIUSARI, 1971; PÄTRUT et aI., 1976). The most important contributions in point of wealth 1983). of data on taxonomy and stratigraphic occurrences and It is now obvious that the areal and stratigraphic dis- also of excellent illustrations are those of SIMIONESCU tribution patterns of the Jurassic brachiopod faunas in (1910 b) and PATRULIUS& ORGHIDAN(1964). Dobrogea were closely dependent on both the regional In this paper the taxonomy was prepared by the second paleogeographic frame and the local changing environ- author, while most of all other sections were jointly written mental factors. As a direct consequence, a strong imbal- by both authors. ance resulted in the distribution of the Dobrogean Juras- We have deliberately enlarged the general geologic, sic brachiopod faunas. stratigraphic and facial background of the present paper, In the Central Dobrogean sector, the Jurassic brachio- aiming not only to introduce the reader to the Jurassic ge- pod faunas have had two important development inter- ology of the region, but also to provide a measure of the vals: the first during the latest Bathonian-Early Callovian, progress we have achieved in the knowledge of the Dobro- the second during the Middle Oxfordian-Early Kim- gean Jurassic System as compared with ARKELL'Ssynthe- meridgian. A fairly rich uppermost Bathonian-Lower Cal- sis (1956).

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3. Central Dobrogean of corals and corallophile faunas is to be noticed. Having Upper Jurassic Brachiopod Faunas in view both the spatial development pattern and the tex- ture of the spongalgal-built calcareous masses, two dis- 3.1. Casimcea Formation tinct complexes may be stratigraphically recognized in (Oxfordian-Lower Kimmeridgian): the Vi stern a Series, as follows: An Extensive Brachiopod Occurrence o the lower, Biostromal Complex (Text-Fig. 2 B, fa- in a Shallow-Water Carbonate Platform cies I) is made up of spongalgal boundstones, deve- loped as successive pseudostromata-encrusted The Casimcea Formation, which yielded by far the rich- sponge layers, subordinately interspersed with lenses est and most varied Upper Jurassic brachiopod faunas in of bioaccumulated to bioclastic spongalgal pack- Dobrogea, shows a very impressive polifacial complexity stones-wackestones; for a thickness ranging only from 150 to 500 m. o the upper, Biohermal Complex (Text-Fig. 2 B, fa- DRÄGÄNESCU(1976, 1978, 1979) recognized eight map- cies II) is made up of tangent columnar bioherms, pable facies series or members, highly diachronous, inter- 15-20 m in diameter and 20-70 m high, showing a grading both laterally and vertically in a remarkable facial- lower, massive part composed of bioconstructed ly-ordered distribution pattern, reflecting roughly sub- spongalgal limestones slightly dipping centripetally, parallel depositional belts relating to a presumed shore- towards the center of the bioherms (the massive stage line to the north. of the bioherms) (Text-Fig. 2 B, facies II a), and, re- The brachiopod faunas display a clear-cut, environ- spectively, an upper, ring-shaped part consisting of an mentally-controlled distribution, these being ecologically external, bioconstructed wall, 2-5 m thick, encircling restrained only to some of the facies series. The paleogeo- an internal "microlagoon" filled with slightly cemented, graphic setting of these facies series was a shallow-water, fine-grained spongalgal packstones-wackestones (the open marine depositional area during a regressive cycle, "microatoll" stage) (Text-Fig. 2 B, facies II b). with a variable bottom topography developed upon a dis- sected carbonate platform providing extensive niche par- The depositional environment, corresponding to a rath- titioning available for high brachiopod colonization. er plane, constructional platform having little topographic In order to emphasize the particularities of the areal and elevation above the surrounding sea-floor, was similar to stratigraphic distribution patterns of the brachiopod fau- that depicted by GAILLARD(1983) for the same type of fa- nas, and thus to account for their environmental control, cies evolving in Southern Jura. The absence of any wash- the brachiopod-bearing facies series of the Casimcea ing in the spongalgal facies suggests that its deposition Formation will be characterized both Iitho- and biofacially took place at depths varying between 10 and 20 m below following DRÄGÄNESCU(1976), and, respectively, SIMIONES- mean sea-level, in generally low- to moderate-energy en- CU (1910 a-b), PATRULIUS& ORGHIDAN(1964) and BÄRBU- vironments, below wave base in offshore shelf areas, but LESCU(1968, 1969 a-b, 1970, 1971 a-b, 1972, 1974, 1976, within the reach of shoaling currents. The upper limit of the 1979). depth range corresponds to the common wave base and the lower one to the generally accepted maximum depth for symbiotic blue-green algae activity. Although the outcropping areas of the Vis t ern a 3.1.1. Vi sterna Bioconstructed Spongalgal Series Se r i e s are much more extensive than those of the other (Text-Fig. 2 B, facies series I and II a-b) facies series of the Casimcea Formation, only few local- It consists of bioconstructed spongalgal limestones to ities delivered quite rich brachiopod assemblages. which bioaccumulated to bioclastic spongalgal lime- When referring to the stratigraphic occurrence and fa- stones are quite subordinately associated. The lime- cies connection, the brachiopod assemblages of the stones are composed mainly of patelliform sponges, lower, Bio s t rom a I Com pie x are fairly different from pseudostromata crusts and oncolitic grains. The absence those of the upper, Bio her m a I Com pie x .

Text-Fig.2...... Stratigraphic and facial distribution of brachiopods in the Upper Jurassic of Central Dobrogea. Lithostratigraphy: DRAGANESCU(1976); Biostratigraphy: BARBULESCU(1974, and new data). A) Western-CentraIDobrogea. Facies series of the Casimcea Formation: I = Visterna Bioconstructed Spongalgal Series, Biostromal Complex; II = Cekirgea Stromatolitic Algal Series; V = Topalu Bioconstructed Coralgal Series. Species index: 1 = Laeunosella sp.; 2 = Moesehia alata; 3 = Laeunosella eraeoviensis; 4 = Aeanthorhynehia spinulosa; 5 = Montielarella strioplieata; 6 = Moesehia alata; 7 = Argovithyris baugieri; 8 = Dorsoplieathyris fareinata; 9-10 = Plaeothyris earsiensis; 11-12 = Zeillerina delemontana; 13 = Dietyothyris kurri; 14 = Torquirhynehia speeiosa; 15 = Moesehia granulata; 16 = Dorsoplieathyris petersi; 17 = Juralina subformosa; 18 = J. bullingdonensis; 19 = Zeillerina delemontana; 20 = Crania lamellosa; 21 = Cheirothyris f1eurieusa; 22 = Septaliphoria pinguis; 23 = S. moraviea; 24 = Terebratulina (Cruralina) substriata; 25 = Ismenia peetuneuloides; 26 = Digonella sp.; 27 = Torquirhynehia speeiosa; 28 = Aulaeothyris sp.; 29 = Juralina kokkoziensis; 30 = Juralina sp.; 31 = J. topalensis; 32 = Zeillerina delemontana; 33 = J. eastellensis; 34 = Septaliphoria moraviea. B) Eastern-CentraIDobrogea. Facies series of the Casimcea Formation: I = Visterna Bioconstructed Spongalgal Series, Biostromal Complex, II = Visterna Bioconstructed Spongalgal Series, Biohermal Complex: a = massive stage, b = "microatoll" stage; III = Gara Tärgu~orTriturated Spongalgal Series; IV = Särtorman Corpuscular Algal Series; V = Topalu Bioconstructed Coralgal Series. Species index: 1 = Moesehia alata; 2 = Argovithyris stoekari; 3 = Laeunosella aroliea; 4 = L. trilobataeformis; 5 = Argovithyris baugieri; 6 = Nueleata nueleata; 7 = Dorsoplieathyris fareinata; 8 = Zeillerina delemontana; 9 = Plaeothyris earsiensis; 10= Septoerurella saneteelarae; 11 = Agerinella lyrata; 12 = Crania lineata; 13 = Craniseus suevicus; 14 = Crania lamellosa; 15 = Montielarella cf. triloboides; 16 = M. roilier!; 17 = M. strioplieata; 18 = Trigonellina intereostata; 19 = T. aft. peetuneulus; 20 = Crania laevissima; 21= Terebratulina (Cruralina) substriata; 22 = Trigonellina trimedia; 23 = Plaeothyris sp.; 24 = Laeunosella sp.; 25 = Dorsoplieathyris sp.; 26 = Dietyothyris kurri; 27 = Ismenia peetuneuloides; 28 = Aeanthorhynehia spinulosa; 29 = A. senticosa; 30 = Rioultina virdunensis. Lithology: 1 = bioconstructed spongalgallimestone; 2 = bioclastic (triturated) spongalgallimestone; 3 = echinalgal, oncolitic limestone; 4 = dolomite; 5 = well-bedded calcilutite, biomicrite-biocalcarenite; 6 = stromatolitic limestone: a = ministromatolith; b = megastromatolith; 7 = bioconstructed coralgallimestone of arborescent coral colonies; 8 = bioconstructed coralgallimestone of crustiform colonies.

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From the Biostromal Complex two quite homo- Montie/arella s/riop/ieata (QUENSTEDT) geneous brachiopod faunas were collected in the Ca- Montie/are//a rollieri WISNIEWSKA simcea valley and, respectively, in the Särtorman valley Montie/are//a cf. tri/oboides (QUENSTEOT) (Text-Fig. 4, locs. 5 and 6). Laeunose//a sp. In the Casimcea valley, on the right-hand bank, 1000 m Aeanthorhynehia spinu/osa (OPPEL) south of Cheia village, the limestones occurring in the Aeanthorhynehia sentieosa (SCHLOTHEIM) basal part of the Biostromal Complex, very rich in P/aeothyris sp. crinoid debris, contain besides silicisponges, bivalves, Dorsop/ieathyris petersi n .sp. rare ammonoids and nautiloids, a relatively varied bra- Dorsop/ieathyris sp. chiopod fauna, from which the following species were Dictyothyris kurri (OPPEL) identified: Dietyothyris cf. ro//ieri (HAAS) Septoerure//a sanetee/arae (ROEMER) Terebratu/ina (Crura/ina) substriata (SCHLOTHEIM) Montie/are//a strioplieata (QUENSTEDT) /smenia peetuneu/oides (SCHLOTHEIM) Laeunose//a aro/iea (OPPEL) Trigone/lina intereostata (QUENSTEOT) Laeunose//a tri/obataeformis WISNIEWSKA Trigone/lina /orieata (SCHLOTHEIM) Argovithyris stoekari (MOESCH) Trigone/lina peetuneu/us (SCHLOTHEIM) P/aeothyris sp. Trigone//ina trimedia (QUENSTEDT) Moesehia a/ata (ROLLET) Agerine//a /yrata PATRULIUS Nue/eata nue/eata (SCHLOTHEIM) Riou/tina virdunensis (BUVIGNIER). Zei//erina de/emontana (OPPEL) It must be emphasized that the species richness of the It is worth mentioning that the last species, otherwise above-listed brachiopod fauna is very impressive as com- very rare in Central Dobrogea, has a high frequency in this pared with those found in the two foregoing localities. It locality. The associated ammonoid fauna, including Cam- seems more likely that this apparent richness should be py/ites (Neoprionoeeras) /autlingensis (ROLLIER), Sowerbyeeras tor- rather an expression of the virtual existence of several dis- tisu/eatum (D'ORBIGNY), Euaspidoeeras sp. ex gr. E. perarmatum tinct paleocommunities within the Bio her m a I Com- (SOWERBY),is indicative for the Middle Oxfordian- Transver- pie x of the Vis t ern aSe r i es. As already stressed the sarium Zone. fauna studied by PATRULIUS& ORGHIDAN (1964) undoub- In the second locality, situated in the Särtorman valley, a tedly represents a secondary concentrated loose rich brachiopod fauna, besides rare and poorly-preserved material. However, this is not a major inconvenience, as ammonoids, was collected by DRÄGÄNESCU,including: this collective brachiopod fauna, although taken as a Laeunose//a aro/iea (OPPEL) whole, gives us an appropriate idea on the taxonomic va- Laeunose//a tri/obataeformis WISNIEWSKA riety of brachiopod paleocommunities living in the Argovithyris stoekari (MOESCH) Biohermal Complex of the Visterna Series, and Dorsop/ieathyris fareinata (DOUVILLE) thus permitted to compare them globally with the coeval P/aeothyris sp. brachiopod paleocommunities of the contemporaneous Moesehia a/ata (ROLLET) Upper Jurassic shallow-water facies series of the Ca- Moesehia sp. simcea Formation occurring in Central Dobrogea. Nue/eata nue/eata (SCHLOTHEIM) Biostratigraphically, most of the above-listed brachio- Zeillerina de/emontana (OPPEL). pod species, illustrated in PATRULIUS& ORGHIDAN'S paper, Three of the above-mentioned brachiopods in the two have a much longer stratigraphic range, being recorded in localities, i.e. Laeunose//a tri/obataeformis, Argovithyris stoekari the Middle Oxfordian-Lower Kimmeridgian (a, ß units) and Nue/eata nue/eata, are illustrated on PI. 1 (Figs. 17-19 limestones from Swabia and Franconia. A comparison and Figs. 21-24) in the present paper. with the coeval brachiopod faunas from the western part From the Biohermal Complex very rich and varied, of Central Dobrogea points to the absence or scarcity of mostly silicified, Late Jurassic faunas, etched by natural the large-sized Rh Y n c h 0 n e II i d a e and Te re bra tu - chemical weathering of the spongalgal limestones, were lid a e species commonly occurring there. recovered in the Visterna valley (Text-Fig. 4, loc. 7) during A quite similar small-sized fauna was collected by the washing and sieving of the residual clays accumulated in a second author from the lower part of the Bio her m a I series of natural caves. These faunas, described and illus- Com pie x outcropping on the left-hand bank of the Vis- trated by PATRULIUS& ORGHIDAN(1964), are composed of terna valley, nearby the railway bridge, including Monti- Hyalospongea-type silicisponges (Cratieu/aria), numerous e/are//a sp., Riou/tina virdunensis (BUVIGNIER), besides large- cyclostome bryozoans (Ceriopora spp.), brachiopods, ser- sized specimens of Laeunose//a sp., Moesehia sp., P/aeothyris pulid worms, bivalves (Pectinidae, Dimyidae, sp., Dietyothyris kurri (OPPEL) and Zei//erina de/emontana Arc id a e), crinoids (Pentaerinus, /soerinus, Ba/anoerinus), (OPPEL). echinoids (Cidaroidea). Few specimens of Arisphinetes sp. ex gr. A. p/ieati/is (SOWERBY) and Gregoryeeras riazi (GROS- SOUVRE)were collected from the underlying limestones, so that the limestones which have yielded the above-men- 3.1.2. Cekirgea Stromatolitic Algal Series tioned faunas can be assigned to the Upper Oxfordian-Bi- (Text-Fig. 2 A, facies series II) mammatum Zone). The excellently-preserved, generally The most important development area of this series, re- small-sized brachiopod fauna includes the following spe- stricted only to the western part of Central Dobrogea, is to cies (PATRULIUS & ORGHIDAN, 1964; BÄRBULESCU, new be found in the Cekirgea-Veriga sector, northwards of To- material): palu. This facies, built up exclusively by stromatolitic Crania /ineata (QUENSTEDT) boundstones, displays two different morphologic groups: Crania /amellosa (QUENSTEOT) mega- and ministromatoliths, respectively. Crania /aevissima PATRULIUS The megastromatoliths, ascribed to the LLH-C Craniseus suevieus (QUENSTEDT) type, are built up of continuous-stromatolitic masses

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evolved from the superposition of continuous-stromatolit- LORIOl) are indicative for the Middle Oxfordian-Antecedens/ ic laminae, calcilutitic to calcarenitic in grain size, 1 mm to Parandieri Subzones. The Bifurcatus Zone is represented by 2 em in individual thickness. Depending on the amplitude the index species, P (Oichotomoceras) bifurcatus (QUENSTEDT). of the wave-shaped component laminae, the megastro- The lower part of the Bimammatum Zone is documented by matoliths vary from high-domal (more than 0.5 m in wave Epipeltoceras berrense (FAVRE), Euaspidoceras hypselum (OPPEL), amplitude) to low-domal (0.2-0.5 m in w.a.) and quasipla- whereas the upper part by Epipeltoceras bimammatum (QUEN- nar stromatoliths (less than 0.2 m in w.a.). STEDT), Ochetoceras marantianum (D'ORBIGNY), Oecipia topalensis The ministromatoliths, by far the richer in en- (SIMIONESCU), etc. The upper part of the Ce kir g e a trapped faunal elements, are represented by continuous Se r i e s yielded Idoceras laxevoluta (FONTANNES)and Sutneria bioconstructed structures consisting of small columnar galar (OPPEL), which are representative for the Planula Zone stromatoliths either of SV-type or LLH-S type, and fine- in the Late Oxfordian, and also an Early Kimmeridgian am- waved quasiplanar stromatoliths. monite fauna including Physodoceras contemporaneum (FAVRE), Whereas in the lowermost part of the Ce kir g e a P fiparum (OPPEL), Aspidoceras sp., Ataxioceras sp. ex gr. A. Se r i e s the two types co-occur, the major remaining part (Parataxioceras) inconditum (FONTANNES). of this facies is alternatively composed of megastromato- Two stratigraphically distinct brachiopod assemblages liths or of ministromatoliths. The stromatolitic facies has are occurring in the Cekirgea Series, the one being developed as a continuous barrier-bank, resulting in an allied to the sponge-bearing lower section and the other to extensive biostrome covering the western Central Dobro- the coral patch reef-bearing upper section. The difference gea and displaying a final thickness as high as between the two assemblages is not likely to be due to 150-170 m. distinctiveness in taxonomic level but mainly to the rela- The stromatoliths seem to have had an original hard tive abundance of some species and subordinately to the consistence, due to a rapid lithification of laminae, as entering of some new species. shown by severallines of evidence: the attachment of the The first brachiopod assemblage (Text-Fig. 2 A - Middle epibiont faunas (sponges, ostreids, brachiopods) to the to basal Upper Oxfordian; Text-Fig. 3, loc. 3) includes the surface of several laminae, without causing bending or following taxa: sagging as a loading effect; the open, tubular voids Monticlarella strioplicata (QUENSTEDT) strongly resembling organic borings in a hard substratum; Monticlarella rolfieri WISNIEWSKA the frequent microerosional surfaces occurring into the Lacunosella cracoviensis (QUENSTEDT) megastromatoliths that sharply cut across the laminae. Acanthorhynchia spinulosa (OPPEL) Some megastromatolitic layers display interruption in the Septaliphoria sp. stromatolith upward-growth and dolomitized tops, which, Argovithyris baugieri (D'ORBIGNY) besides the occurrence of desiccation cracks and Oorsopficathyris farcinata (DOUVillE) borings, indicate that they built up to intertidallevels, be- Placothyris carsiensis (SIMIONESCU) ing locally subjected to subaerial exposure. Moeschia alata (ROllET) As for the depositional environment, the association of Juralina topalensis (SIMIONESCU) the stromatoliths with typical shallow-marine benthic fau- "Terebratula" dobrogensis (SIMIONESCU) nas (sponges, corals, brachiopods, bivalves, echino- Oictyothyris kurri (OPPEL) derms) is congruent with a sedimentation in a wave- Nucleata nucleata (SCHLOTHEIM) agitated, shallow subtidal, marine environment, the de- Terebratulina (Cruralina) substriata (SCHLOTHEIM) pths ranging presumably between 5 and 10 m, much shal- Zeillerina delemontana (OPPEL) lower than for the spongalgal facies series. Ismenia pectunculoides (SCHLOTHEIM). The main paleontologic characteristic for the lower part of the Cekirgea Series is given by the abundance of The above-listed assemblage includes several brachio- the large-sized silicisponges, usually with cylindrical to pods normally occurring in the sponge-bearing facies conical, columnar forms, and subordinately plate-like elsewhere, such as Lacunosella cracoviensis (sharing small- forms, also by the high frequency and large variety of the sized, asymmetric specimens in the Transversarium Zone ammonite and brachiopod faunas. For the Veriga sector, it and large-sized, either asymmetric or symmetric, speci- is very interesting to note the gradual transition from the mens in the Bimammatum Zone), Moeschia alata, Oorsoplicathyris sponge-bearing facies in the lower section of the Ce- farcinata, besides the large-sized Placothyris carsiensis and kir ge aSe r i e s to a facies lodging scattered coral patch Zeillerina delemontana. Also, there occur frequently Acantho- reef in the uppermost part of the same series, which paved rhynchia spinulosa, Oictyothyris kurri and subordinately the the way for the occurrence of the succeeding To p a Iu small-sized Monticlarella strioplicata, Argovithyris baugieri and Bioconstructed Coralgal Series. Terebratulina (Cruralina) substriata. This fauna is occurring in the The very rich faunas associated to the stromatolitic fa- stromatolitic limestones outcropping along the Cekirgea cies in the Cekirgea valley is mainly composed of benthic valley and the Veriga Arm (Danube) cliff, between its con- epifaunal elements, sponges and brachiopods, subordi- fluences with Cekirgea and Scrofeni valleys, and overlaps nately of epi- and infaunal elements, such as bivalves, the sequence from the Transversarium Zone up to the basal echinoderms, worms, bryozoans (SIMIONESCU, 1910 b; part of the Bimammatum Zone. BARBUlESCU, 1968, 1969 a, 1974). The nekton, represented Southwards, when the coralligenous masses are inter- by numerous and varied ammonites, allowed a very well- leaving in the upper section of the Ce k i rg e aSe r i es, constrained biostratigraphy of the Middle Oxfordian-Low- the brachiopod fauna records the highest diversity (Text- er Kimmeridgian sequence (SIMIONESCU, 1907, 1910 a; Fig. 2 A - Upper Oxfordian; Text-Fig. 4, loc. 4 - OX3), but it BARBUlESCU, 1969 b; 1974). Ochetoceras canaliculatum (v. should be noted that the following list checks brachio- BUCH), O. hispidum (OPPEL), O. semifalcatum (OPPEL), Perisphinc- pods which in reality illustrate very diversified life habits tes (Arisphinctes) cotovui SIMIONESCU, P(A.) helenae DE RIAZ, P that intricately have been recurring or intergrading during (Oichotomosphinctes) dobrogensis SIMIONESCU, P (0.) buckmani the latest Late Oxfordian (Planula Zone) in the western part (ARKEll), Gregoryceras sp., P (Perisphinctes) parandieri (DE of Central Dobrogea, viz. stromatolitic, reefal, peri-reefal

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and inter-reefal ones. Hence, the subsequent list collec- side the arborescent coralgal boundstones. The arbores- tively includes the following taxa: cent subfacies evolved as a nearly continuous barrier reef Crania /ineata (QUENSTEDT) originating in an extensive coralgal biostrome, thus illus- Crania /amellosa (QUENSTEDT) trating an extremely shallow subtidal, high-energy en- Montic/arella striop/icata (QUENSTEDT) vironment, less than 1 m in depth, as DRÄGÄNESCU(1976) Lacunosella cracoviensis (QUENSTEDT) stated. Acanthorhynchia spinu/osa (OPPEL) The age of the arborescent subfacies results from its Septa/iphoria pinguis (ROEMER) stratigraphic position, being underlain by Early Kimmerid- Septa/iphoria moravica (UHLIG) gian aspidoceratid-bearing stromatolitic limestones of Torquirhynchia speciosa (MÜNSTER) the Cekirgea Series. The rich coral assemblage, in Dorsop/icathyris farcinata (DOUVILLE) which Epistreptophy//um giganteum RONIEWICZis frequent, as- Dorsop/icathyris petersi n .sp. sesses the same age for the arborescent subfacies. The Dorsop/icathyris sp. other faunas associated to this subfacies include bra- Moeschia a/ata (ROLLET) chiopods, epi- and infaunal bivalves, echinoids, gastro- Moeschia granu/ata BOULLIER pods and small-sized colonies of hydrozoans (BÄRBULES- Moeschia zieteni (DE LORIOL) cu, 1965, 1972, 1974; TURNSEK& BÄRBULESCU, 1969). The Moeschia sp. brachiopod fauna is composed of a remarkable assem- Juralina subformosa (ROLLIER) blage of rhynchonellids and terebratulids (Text-Fig. 2 A Jura/ina bullingdonensis (ROLLIER) -Lower Kimmeridgian; Text-Fig. 4, loc. 4 - km, ), as fol- Juralina castellensis (DOUVILLE) lows: Juralina topa/ensis (SIMIONESCU) Septaliphoria moravica (UHLIG) "Terebratu/a" dobrogensis (SIMIONESCU) Septa/iphoria pinguis (ROEMER) Dictyothyris kurri (OPPEL) Torquirhynchia speciosa (MÜNSTER) Terebratu/ina (Crura/ina) substriata (SCHLOTHEIM) Moeschia granu/ata BOULLIER Zeillerina de/emontana (OPPEL) Jura/ina topa/ensis (SIMIONESCU) Cheirothyris f1eurieusa (D'ORBIGNY) Jura/ina subformosa (ROLLIER) /smenia pectuncu/oides (SCHLOTHEIM) Jura/ina bullingdonensis (ROLLIER) Riou/tina virdunensis (BUVIGNIER). Jura/ina castellensis (DOUVILLE) This brachiopod fauna stands out mostly by the pres- Jura/ina kokkoziensis (MOISEEV) ence of some large-sized species, such as Dorsop/icathyris Jura/ina sp. petersi n.sp., Moeschia granu/ata, "Terebratu/a" dobrogensis, Jura/i- "Terebratu/a" dobrogensis SIMIONESCU na subformosa currently occurring in the coralligenous fa- Terebratu/ina (Crura/ina) substriata (SCHLOTHEIM). cies, whereas the inter-reefal, bedded argillaceous and The rhynchonellid group includes both quite numerous the biodetritallimestones bear only small-sized brachio- asymmetric types, such as Torquirhynchia speciosa, and fairly pods, such as Dorsop/icathyris sp., Terebratu/ina (Crura/ina) sub- frequent trilobate, symmetric types, such as Septa/iphoria striata, /smenia pectuncu/oides, C ran i d a e and rare The ci - moravica, the latter being in our opinion very similar to dei d a e. The rhynchonellids are represented by Septa/i- Rhynchonella moeschi (ROLLIER) sensu MOISEEV (1934). The phoria pinguis and a very large-sized, yet undescribed spe- terebratulids, by far the best represented group, are illus- cies of Septa/iphoria. trated almost exclusively by large-sized Jura/ina species The most representative brachiopod species occurring provided with strong and erect umbo, such as J. topa/ensis, in the two facially distinct sections of the Ce kir ge a J. kokkoziensis, J. subformosa. Large-sized specimens of Zei/- Se r i e s are illustrated on Plates 2 and 3 in the present /erina de/emontana and very rare Digonella sp., Au/acothyris sp., paper. Cheirothyris f1eurieusa and /smenia pectuncu/oides are also to be found. Some brachiopod species occurring in the arborescent 3.1.3. Topalu Bioconstructed Coralgal Series coralgal subfacies of the To p a IuS e r i es are selectively (Text-Fig. 2 A, facies series V) figured on Plates 3 and 4 in the present paper. It corresponds to the upper sedimentary body of the homonymous facies series occurring at several strati- As it clearly results from the above presentation, the Ce- graphic levels in the Central Dobrogean Oxfordian-Lower kirgea- Topalu sector, by its very rich and varied brachio- Kimmeridgian sequence. pod faunas, is the reference region in Dobrogea for the Up- Largely widespread in the westernmost part of Central per Jurassic brachiopod faunas connected both with the Dobrogea (Topalu-Capidava sector) and directly overlying C ek i rg e abi oe 0 n stru cted co ra I g a I fac i es and the Ce kir ge aBi 0 con s t rue ted S t rom at 0 lit i c the Topalu Bioconstructed Coralgal Facies, Algal Series, the Topalu Bioconstructed while the Casimcea Zone is the reference region for the Cor a I g a I Se r i es starts with the arborescent coralo- Upper Jurassic brachiopod faunas allied to the Vis t e r- pseudostromata subfacies, the so-called "Topalu reef" in n abi 0 con s t rue ted s p 0 n g a I g a I fa eie s. Outside the previous literature, being largely exposed along the of these reference regions, coeval brachiopod faunas, Veriga Arm (Danube) cliff - northwards of the Topalu vil- much less varied and not so rich, occur also in other local- lage, and also in the Tätaru valley, running across the To- ities north of the Cekirgea valley, such as the Atarnati palu village. It includes prevailingly variable-sized ar- point, also the Baroi and "La Vii" hills, north of Har1?ova borescent and, subordinately, spheroidal and crustous town, always for the Cekirgea stromatolitic algal corals (about 70 species inventoried by RONIEWICZ,1976), fa eie s. It is notable in both localities (Text-Fig. 4, locs. coated by pseudostromata crusts that usually fill up the 1-2), that northwards of the Cekirgea- Topalu sector a inter-calyx spaces of arborescent colonial corals; in minor marked decline in diversity of the brachiopods took place, amounts, coralgal grainstone lenses and fillings occur in- and also that the distinctiveness at the taxon level

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between the Middle Oxfordian and, respectively, the Up- downthrown side of the transtensional Peceneaga-Came- per Oxfordian-Lower Kimmeridgian sections of the Ce- na Fault, and a "southern" highstanding sliding block on kir g e aSe r i e s is more strikingly expressed here. the upthrown side, i.e. the Central Dobrogean "Green In the following sections of the present paper, various Schists Block", limited bya basinward-facing seismically paleoecologic and taphonomic aspects, as well as the pa- active fault-scarp. The assumption of an asymmetric leobiogeographic affiliation of the Central Dobrogean Up- half-graben structure allows us to better understand the per Jurassic brachiopod faunas will be analyzed. obviously asymmetric carbonate facies distribution in the Although general knowledge of the Upper Jurassic bra- Cärjelari area, that exhibit coarse-grained facies at the chiopod faunas from Central Dobrogea is much expanded steep and straight, strike-slip margin, the deposition site by the present paper further more detailed studies will un- for the Sf ä n t a Fa eie s, and finer-grained facies at the doubtedly contribute to a better understanding of other gentler gradient, irregular and broader "normal" margin, intimate aspects, e.g. the distribution of brachiopods in the deposition site of the A mar a Fa eie s . the varied depositional subenvironments of the complex The Sf ä n t a Fa eie s, developing in the Sfänta hill and Vis t ern a and Ce kir g e a fa eie sse r i es. Lastly, the the "Vararia" quarry-hill, about 600 m thick in the exposed richness and high taxonomic diversity of the Oxfordian- sequence, and showing a weakly-developed or indistinct Lower Kimmeridgian brachiopod faunas from Central Do- bedding (Text-Fig. 3), is composed of Iight-coloured, pre- brogea leave abundant scope for minute studies of evolu- vailingly bioclastic limestones, ranging in size from cal- tion in species-Ievellineages in the fossil record. As at pre- cilutites to calcirudites, associated with scarcely occur- sent there is relatively little information bearing on the bra- ring calcilutites, oolitic calcarenites and various bioli- chiopod phylogenesis spanning this time interval, it would thites. The carbonate rocks of the Sf ä n t a Fa eie s are be highly interesting to study the genetic variability and stratigraphically bounded by or are commonly interlacing the adaptive responses of the Central Dobrogean Upper with unsorted and poorly cemented, matrix- or clast-sup- Jurassic brachiopods to the different shallow-water car- ported disorganized polymictic conglomerates, gray bonatic environments which could have triggered mar- spongolitic or spongo-radiolarian gaizes and spiculitic kedly differing phylogenetic lineages. marls of Ba~punar Formation-type, and rhyolitic air-fall To answer the purpose of the present paper, brachio- tuffs (Sfänta Tephra), usually as lensoid bodies. At some pods from different Central Dobrogean Upper Jurassic fa- levels on the southern slope of the Sfänta hill, also west of cies series have been selectively illustrated on the accom- the "Vararia" quarry, the fine-grained carbonate rocks of panying plates. Since the brachiopods of the Vis t ern a the Sf ä n t a Fa eie s show a massive influx of well-sorted Se r i es were already well figured by PATRULIUS& ORGHI- and graded, angular-shaped clasts of Central Dobro- DAN(1964), those interested are referred to their paper. gean-type "Green Schists", sometimes even as huge The present study is completed with the description of a olistoliths. These mixtites or pebbly mudstones were for- new species, Dorsoplicathyris petersi n.sp., to commemorate med by admixture of the gravitationally-emplaced "Green the important contribution of PETERS(1867) to the know- Schists" epiclastites with the intraformationally-reworked ledge of Upper Jurassic brachiopods from Central Do- carbonate sediments of the Sf ä n t a Fa eie s. They re- brogea. The generic assignment of Placothyris carsiensis present distal facies of mass- and turbidity flows genetic- (SIMIONESGU)is also revised. ally relating to the Amara Breccia, a very coarse-grained All illustrated specimens have been assigned Labora- clast-supported monomictic sedimentary breccia made tory of Paleontology - Bucharest University catalogue up exclusively of unsorted cobble- to boulder-sized, angu- numbers and are housed in the type collection of this in- lar-shaped blocks of the Central Dobrogean-type "Green stitution. Schists" bound within a whitish calcareous matrix. The Amara Breccia is interpreted as a remnant of once more extensive fault-scarp scree breccia draping the northern 4. North Dobrogean seismically-active strike-slip margin of the Central Dobro- Upper Jurassic Brachiopod Faunas gean "Green Schists Block", as a narrow fringe pinching out into or lapping the coeval carbonate deposits of the 4.1. Cärjelari Formation - Sfänta Facies Cärjelari Formation. (Oxfordian-Lower Kimmeridgian): The intricately interspersed lithologies of the Sf ä n t a A Restricted Brachiopod Occurrence Fa eie s may be explained as the result of the catastrophic in a Transtensional Basin disintegration of the carbonate sediments due to the syn- sedimentary repetitive transtensional slipping of the ba- In the Cärjelari Zone (Text-Fig. 1), the Upper Jurassic sinward-facing faulted-margin of the Central Dobrogean carbonate rocks of the Cärjelari Formation are occurring "Green Schists Block". Concomitantly, short-lived phases in two NW-SE trending, en echelon-arranged, morpholo- of rapid sinking of the sedimentary area nearby the lead- gical alignments, the north-eastern Amara alignment and, ing edge of the Central Dobrogean Block has allowed the respectively, the south-western Sfänta alignment, which westward recurrent onlapping of the Ba~punar Forma- are tectonically separated by the Hasanlar Fault. The two tion-type deep-water spongo-radiolarian gaizes over the distinct carbonate facies characterizing the respective tectonically collapsed shallow-water carbonate rocks of alignments, i.e. the Amara Facies and the Sfänta the Sf ä n t a Fa eie s . Fa eie s, respectively, represent remnants of the two car- All the particular lithologies associated with the col- bonate deposition belts corresponding to the formerly op- lapse breccias of the basinward-facing Central Dobro- posite margins of the Peceneaga-Camena transtensional gean Block fault scarp document intermittent, seismic basin (GRÄDINARU,1988). fault movements with both strike-slip and dip-slip com- The strikingly differing major sedimentary features of ponents occurring concurrently with sedimentation. As a the two facies demonstrate a clear-cut asymmetric consequence, the Sf ä n t a Fa eie s of the Cärjelari For- cross-sectional morphology for this basin, with a "sta- mation, when examined on a larger scale, especially in the tionary", fault-angle depression on the "northern" area of the Sfänta hill, shows a weakly developed bedding

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A. Carjelari Zone B. Tulcea Unit

z "" "" '" "" "" a c -5» - ~-- / rtl Q 9 0 ~ c Cl . "'C « ::E -=" C L.. E .;. OJ o er 0_ rtl => E ~:-::: E a ~ :I: to ~ u.. ~ VI "'C QI~ .- VI L- L- eu OJ to 2 -0 3: u.. 0 -0 ::;: o .... o -.J to X I c: c .'" a -' rtl VI Callovian L- a c ::E .... 0 . • .0-.0•0 • t« rtl u.. E x .0 0.0 • C 0 "J"T"••••• '.- ---- •• ' a ..c •••••••• :::>8 +- .' ••.•• ;-r;- .• " ~'l rtl co :...-:.:-...... -::..::.-,: :~~ AIORMAN FM I C Q-ij" . :.::cf;,' « ~ 7 I-----j rtl 6 ~~~-<:> ••••.••• :::>~z... U 5 ...... 0 ~H1~~I rtl ag-zE co 4 ~ "" 3 -- .:.~.=:- ~ 1 T.:::o_...... 2 1°.00o • 0.1• (f)~...... ~ I Text-Fig.3. Stratigraphic distribution of brachiopods in the Upper Jurassic of North Dobrogea. Lithostratigraphy and general biostratigraphy: GRÄOINARU(1984, 1988); Brachiopod biostratigraphy: GRÄOINARU& BÄRBULESCU(in the present paper). A) Cärjelari Zone. Cärjelari Formation, Sfänta Facies. Species index: 1-2 = Torquirhynchia astieriformis; 3 = Moeschia granu/ata; 4 = Jura/ina cf. subformosa; 5 = Zei//erina sp. BI Tulcea Unit. Carabair Limestone. Species index: 1 = Montic/are//a czenstochowiensis; 2 = Lacunose//a sparsicosta. Lithology: A) Cärjelari Zone: Aiorman Formation: 1 = terrigenous turbidites; Cärjelari Formation, Sfänta Facies: 2 = polymictic conglomerates; 3 = marly and silty shales; 4 = rhyolitic air-fall tuffs and spongo-radiolarian gaizes; 5 = bioclastic and oolitic limestones; 6 = pebbly mudstones with Central Dobrogean "Green Schists" epiclastites; 7 = local outcropping sequence. B) Tulcea Unit: Dunava\u Formation: 1 = terrigenous turbidites organized in Ta, Tae, Ta-e and rare Tcde or Tde Bouma sequences, with non-Ieeved distributary channels, mudstone rip-up clasts and sandstone spheroids centered by mud clasts; Carabair Limestone: 2 = crinoidal calcarenites and pelagic marly limestones with cherty nodules and lenses. and lenticular-shaped bodies of the constituent rocks ciated with arenite-sized algal corpuscles, usually cor- which accounts for the interpretation of this facies as a toids, lumps and onkoids. Reef rudstones with debris of huge synsedimentary megabreccia of seismotectonic arborescent colonial corals and coated bioclasts of vari- collapse origin. ous corallophile faunas are also to be found. Oolitic and Microfacially, the coralgal and echinalgal packstones to oolitic-bioclastic packstones to grainstones, lumpal grainstones are the main types which characterize the car- packstones, spiculitic wackestones, pseudostromata bonate rocks of the Sf ä n t a Fa c i es. They contain are- algal bindstones and crustous sponge-bearing biolithites nite- to rudite-sized skeletal grains, usually bioclasts, only are sparsely encountered in the Sf ä n t a Fa ci es. rare biomorpha, of corals, hydrozoans, chaetetids, cal- By their biofacies, the calcareous rocks of the Cärjelari cisponges, echinoderms, foraminifera, bryozoans, gas- Formation are highly consanguineous with the shallow- tropods, bivalves, brachiopods, crustaceans and scarce water rocks of the Central Dobrogean Oxfordian-Lower fragmentary ammonites of perisphinctid-type, asso- Kimmeridgian carbonate platform. The radiolarian fauna

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of the spongo-radiolarian gaizes interbedded in the presents the single outcropping lithostratigraphic term of Sf ant a Fa ci es, in the Homurlar valley, is also indicative the Upper Jurassic Series, highly removed by the subse- for the Oxfordian-Early Kimmeridgian time interval (Du- quent erosion. It corresponds to the so-called "Planu- MITRICÄ,in GRÄDINARU,1988). laten-Kalkstein vom Kara-bair", whose presence in the Depositionally, the Carjelari Formation represents the Dunavälu region was previously mentioned by PETERS westward, seismically-disturbed, shallow-water counter- (1867:189). All the later field-works in the region failed to part of the coeval deep-water rocks of the Ba~punar identify the outcrop area of these limestones, until the Formation, which are intricately intergrading with con- 1970s, when the recovery of an old paleontological temporaneous, intermittent submarine hot-gas-fluidized material, which was collected by $TEFÄNESCU(1906) in the pyroclastic flows, rhyolitic lava flows and quenched hy- same region, made actual once again PETERS'very impor- droclastic deposits, and finally topped by spilitized ba- tant finding and the above-mentioned outcrop area was saltic lava flows. finally identified (GRÄDINARU,1984). The occurrence of brachiopods in the limestones from The Carabair Limestone, with only a partially exposed the Carjelari area was recorded by PETERSas early as 1867. sequence, around 50 m thick, shows light gray crinoidal He mentioned "Rhynchone//a concinna SOWERBY", on which a calcarenites and mainly dark gray, fine-grained pelagic Middle Jurassic age has been assigned to the limestones, marly limestones, showing odd, dark-black chert nodules although the facies and the occurrence of other macrofau- and lenses (Text-Fig. 3). These limestones yielded a few nas seemed to suggest their similitudes with the Upper epiplanktonic bivalves, rare belemnites, but a fairly abun- Jurassic carbonate rocks examined by him along the dant ammonoid fauna, including Sowerbyceras tortisu/catum Danube clift of Central Dobrogea. POMPECKJ(1897), com- (D'ORBIGNY), Ho/cophylloceras zignodianum (D'ORBIGNY), Oche- pared the faunas of the Carjelari limestones with those of toceras hispidum (OPPEL), G/ochiceras subc/ausum (OPPEL), Dicho- the "Calcare a Terebratula janitor" from Sicily. SIMIONES- tomosphinctes elisabethae (DE RIAZ), D. sp. ex gr. D. wartae (Bu- CU (1911) described, besides other varied macrofossils, KOWSKI),Dichotomoceras bifurcatoides ENAY, D. sp. ex gr. D. ste- three brachiopod species, i.e. "Rhynchonella corallina LEYM.", nocyc/oides (SIEMIRADZKI),which are diagnostic for the Trans- "Terebratu/a aft. formosa SUESS" and" Terebratu/a sp. ex gr. bisuf- versarium and basal Bifurcatus Zones of the Middle Oxfor- farcinata Sow.", some specimens of the last one being in dian. author's opinion quite similar to "Ter farcinata Douv." and Only very scattered, small-sized specimens were "Ter Zieteni LOR", commonly occurring in the Upper Juras- yielded by the Carabair Limestone, which are attributable sic strata from Central Dobrogea. Accordingly, SIMIONESCU only to two taxa which are figured on PI. 1 (Figs. 1-5) in the compared with good reason the Carjelari limestones with present paper, as follows: those occurring in the Topalu area. Montic/arella czenstochowiensis (ROEMER) New brachiopods were collected from the Carjelari area Lacunosella sparsicosta (QUENSTEDT). by the senior author of the present paper, mainly from the It is worth mentioning that the first record of brachio- fine-grained, whitish biodetrital limestones occurring in pods in this region was made also by PETERS(1867) who the median part of the "Väräria" quarry. Here, besides epi- cited" Rhynchonella /acunosa SCHLOTHEIM". faunal bivalves and crustaceans, a fairly abundant but low diverse brachiopod fauna is occurring, with species of wide size range from juvenile through gerontic growth stage, including the following taxa: As compared with Central Dobrogea, the Dobrogean Torquirhynchia astieriformis CHilDS areas lying north of the Peceneaga-Camena Fault show a Moeschia granu/ata BOUlLiER drastic impoverishment of the North Dobrogean Upper Moeschia sp. Jurassic brachiopod faunas, thus reflecting a coincident Jura/ina cf. subformosa (ROLLIER). northward decrease in environmental stability from the One single specimen of Zeillerina sp. has been collected stable carbonate platform of Central Dobrogea to the tec- on the northern slope of the Sfanta hill in the biodetrital tonically-active Peceneaga-Camena transtensile basin. limestones occurring upwards of the exploration mining Text-Fig. 4 points out that the Dobrogean Upper Jurassic gallery, while one fragmentary specimen of Torquirhynchia brachiopod faunas tend to show a marked northward di- sp. has been found in the large quarry open on the south- versity reduction. A major decreasing gradient of this ern slope of the Sfanta hill. Most of these brachiopods are parameter may be observed when going from Har~ova commonly occurring in Central Dobrogea in the Upper Ox- area towards Carjelari. As already emphasized, there are fordian-Lower Kimmeridgian sequence. severallines of compelling evidence which strengthen that The well-preserved specimens in this fauna are illus- the Central Dobrogean carbonate platform was in close trated on PI. 1 in the present paper. paleogeographic connections with the Peceneaga-Came- Finally, the brachiopod fauna in the Carjelari limestones na transtensional basin, mainly in its western, shallow-wa- of Sf ant a Fa ci es evinces either an extremely restricted ter wedge-shaped segment (GRÄDINARU, 1988), thus ac- or a very dispersed occurrence, as major characterizing counting for free faunal communications. However, major features. physical changes in environmental conditions allowed on- ly transient successful settlement of the brachiopod fau- nas in the Carjelari area during Late Jurassic times. 4.2. Carabair Limestone The much more pronounced impoverishment of the (Middle Oxfordian): coeval brachiopod faunas in the Tulcea Unit was due to the A Scattered Brachiopod Occurrence deeper water environmental conditions. in a Deep-Water Carbonate Basin All the illustrated specimens of the North Dobrogean Upper Jurassic brachiopod faunas from Carjelari and Du- The Carabair Limestone, poorly developed in the east- nävalu de Jos localities have been assigned Laboratory of ernmost part of the Tulcea Unit, with only a small exposure Paleontology - Bucharest University catalogue numbers westerly of the Dunavälu de Jos locality (Text-Fig. 1), re- and are housed in the type collection of this institution.

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5. Paleoecologic Analysis fa eie s (Text-Fig. 2). All these evironmentally distinct bio- facies assured very efficient living opportunities for plenti- In order to delineate the relationships between the vari- ful brachiopod communities. In all instances, these nor- ous characteristic Oobrogean Upper Jurassic brachiopod mal-marine, shallow-water biogenous carbonate facies faunas and the different paleoenvironments in which they provided both extensive firm substrates available for at- have lived, our attention will be further focused on some tachment and ample nutrient supply. Particularly, the stro- elements concerning their paleoecologic and taphonomic matolitic algal facies, which represented during geologic- features, such as the areal distribution pattern, diversity al times one of the most efficient sites of oxygen genera- and density, size-frequency distribution, preservation tion through oxygen-releasing photosynthesis of cyano- state, brachiopod morphology in response to environ- bacteria, provided a well-oxygenated and consequently a mental factors, brachiopod relationships with other inver- current-swept, nutrient-enriched environment, highly tebrate groups. convenient for the development of very diversified and abundant brachiopod-bearing benthic communities. As for the bioconstructed spongalgal facies, several authors, 5.1. Areal Distribution Pattern such as WISNIEWSKA(1932), AGER(1965), GAILLARD(1983) and BOULLIER(1981), have already interpreted this facies A highly unbalanced distribution pattern of the Upper as being very favourable for the development of brachio- Jurassic brachiopod faunas can be observed on the 00- pod populations, owing mainly to abundant food supplied brogean territory (Table 1 and Text-Fig. 4). Whereas ex- by the intense and constant water-currents produced by tremely rich and very diversified brachiopod faunas were such efficient filterers like sponges. Lastly, the intricate, yielded by the Upper Jurassic shallow-water carbonate successful cohabitation relationships between the corals platform rocks of the Central Oobrogean sector, only very and the varied corallophile faunas of the bioconstructed scarce coeval brachiopod faunas were recovered from the coralgal facies of arborescent colonies, the brachiopods Upper Jurassic shallow-water and, respectively, deep- being a prominent constituent but not exceeding other water carbonate rocks of the North Oobrogean sector. megafaunas, were collectively favoured by the extremely Also, even for each of the two Oobrogean sectors a rather shallow-water, high-energy, wave- and current-agitated irregular distribution pattern of the Upper Jurassic bra- environment, allowing not only well-aerated water and chiopod faunas is to be found. It is firstly for Central 00- high levels of food resources but also numerous and com- brogea, where a quite unequal distribution exists between monly extensive areas suitable for larval settling and the middle-eastern and western zones, respectively ample living spaces for richly brachiopod-bearing benthic (Text-Fig. 4, locs. 1 to 4 vs. locs. 5 to 7). As'for North 00- communities. All these normal-marine, shallow-water brogea, the comparative analysis of the coeval brachio- biogenous carbonate facies record a progressive transi- pod faunas from Cärjelari and Ounavä,u de Jos localities tion from offshore shelf zone to inshore subtidal shoals. also discloses a clear-cut imbalance in brachiopod dis- From the same chart (Text-Fig. 4), it is also noteworthy tribution on the territory of this sector (Text-Fig. 4, loc. 8 that each of the above-mentioned specific biogenous car- vs.loc.9). bonate facies, laterally contiguous but with gradational The quantitative paleobiocoenotic analysis of the 00- contacts, had its own distinct brachiopod community, the brogean Upper Jurassic brachiopod faunas clearly de- distinctiveness of the essentially coeval brachiopod com- monstrates that the complex areal distribution of these munities being reflected at the level of their key species faunas can be conveniently explained as reflecting varied and trophic nuclei, the latter referring to the species bio- ecological grouping, the variation in distribution and taxo- mass dominance as it results from the relative importance nomic composition being evidently related to environ- of species and organism's size. mental differences. The chart portraying the areal dis- Although several brachiopods of the Central Oobrogean tribution pattern of brachiopod taxa on the Oobrogean ter- Upper Jurassic fossil assemblages are either cosmopoli- ritory (Text-Fig. 4), drawn on a count of all specimens be- tan or long-ranging species, thus able to thrive or to sur- ing in our collections, and including also the specimens vive in a variety of environments, it should be mentioned, reported by PATRULIUS& ORGHIDAN(1964), provides the however, that the compositional shifts in the faunal em- best indication of original taxonomic composition and di- phasis, expressed both in taxonomic variety and indi- versity. vidual abundance, of the essentially coeval Central 00- The areal distribution of the Oobrogean Upper Jurassic brogean Upper Jurassic brachiopod assemblages (Text- brachiopod faunas was decisively related to varied en- Figs. 2 and 4), were undoubtedly controlled by environ- vironmental-facial and bathymetric factors, as it resulted mental-facial changes rather than time differences since from the complex analysis of the brachiopod-bearing car- the brachiopod faunas come from a relatively restricted bonate depositional facies made in the foregoing sections stratigraphic interval. of the present paper. Undoubtedly, the adaptation of bra- No significant differences existed between the Central chiopod communities to the variable environments of car- Oobrogean Upper Jurassic biogenous facies as regards bonate sedimentation was related to the differing ecolo- both the food supply and firm substrate availability, thus gical tolerance of the brachiopod taxa to varied physical allowing successful brachiopod settlement. However, it environmental factors, such as substrate, water-depth must be further strengthened that all these laterally con- and energy levels, rates of sedimentation, light intensity, tiguous but faunally distinct Central Oobrogean Upper temperature and salinity. Jurassic brachiopod communities bear clear-cut evi- Primarily, Central Oobrogea evinces a conspicuously dence that strong environmental control was exerted on high settling potential of the Upper Jurassic brachiopod their distribution, and that distinctiveness in their taxo- faunas for such particular biogenous carbonate facies as nomic composition primarily reflects differences in water- those of the Vis t ern abi 0 con s t rue ted s p 0 n g a Ig - -depth and energy levels, and only secondarily differences al facies, the Cekirgea stromatolitic algal fa- in niche-size and trophic amensalism relationships, as cies and the Topalu bioconstructed coralgal main ecologically-governing factors.

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Table 1. Check" list and facial-stratigraphic distribution of Upper Jurassic brachiopods in Central and North Dobrogea. CE" T R A L D 0 B R 0 G E A HORTH f)OBROGJ:.~

Vis t ern a Cr.::r:irgea rap a 1 11 Biocon.sr.ructed Sr..roma'tolitic Bioconstructed Carjelari Carabair Spongalgal Series ri.lgal Series Coralgal Series Forn,ar.ion Fornlation S~p~rfa~ilies & Species Bios troo,. Bioher",. lower upper Co:nple,: Complex con'.plex cc'mplex

CRAl"iIACEA Cr~~ ~ lin;a~a iQvENS~EDTI 0000 Cran a la~~llosa IQ~ENSTEDTI 0000 C~an ft laevissi~a PATRULIUS Cran sc~s su~vicus !QUENSTED~) RhYNCHONELLACEA Septocrurella sanc~~clurae (ROEMER) Monticlar~].la strio~licata (QUENSTEDT) GOO:l 0000 Wontjclarülla rollieri WIS~IEWSKA ::;'000 Hontic:aralla cf.t~iloboidBs IQUENSTEDTI ~ionticlarell.a c7:ßnstQchowiensis (?OEHER) VV~IV Lacuno5~J.la ar~lica (O?PEL) La~unoscila sparsicosta (QUE~ISTEDr) 000:) vvvv Lacunosella :ri:obataeiornis WIS1JIEWSKA Lacunos~j,.ln C!"i;;'\c':l?iB:nsis (QUEiTSTEDT) 0000 C/OOO Lacunosella sp. ~canchorh¥nchia spinulosa (OPPEL) ;)000 0000 Acanthorhync}~ia sen~ic0sa (SCHLOTHEIM) Suprali~horia pi~guis (ROEMER) 0000 ;';;":7.7- Septaliphoria rnoravica (UHLIG) (")000 0000 x:-:;.:x S~praliphoria sp. .)OOC T~rQuirhynchia as~ierifor2is CHILDS ++-r+ Torquir~y~chia specios. (MUNSTER) 0000 XXXX TorquirhYI1~hia sp. +t-++ TEREBB.ATULACEA Dorsoplicatnyri.s farc~.nr:'l.t2\ (DOUVILL!b ---- aoco 0000 Dorsoplic8thyris pet~rsi n.sp. ----. 0000 Dorsoplic~chyris sp. ---- 0000 Placo~hyris carsiensis iSIHIONESCU) ---- 0000 Flacothyris sp. ---- 0000 Argovithyris baugieri ID'ORBIGNY) ooco Argovichyris stockari (MOESCH) ---- Hoeschia alaea (ROLLET) ---- 000.0 0000 Mo~schia granulata BOULLIER 0000 XXXX +++;- Hoeschia zieeeni (OE LORIOLl 0000 x.x?'X ~Ioeschia so. ------0000 +++-t- Juralina subformosa (ROLLIER) 0000 xxxx ++++ Juralina bullingdoncnsis (ROLLIER) 0000 xxxx Juralina castellensis (DOUVILLE) 0000 xx;

Zeillerina de~~~ont~na (OPPEL) 0000 0000 :{XXX Zeilierina sp. xxx:< ++++ Digon

Cheirothyris fleurieusa (J'ORBIGNYI 0000 xxxx Ismenia pec~unculoides iSCHLOTHEIM) 0000 0000 :{XXX Trigonellina intercoscata ~QUENSTEDT) Triqonellina loricata ISCHLOTHEIH) Trigonellina pectunculus ISCHLOTHEIMI Trigonellina trimedia (QUENSTEDTI TH3CIDEIDEA Rioultina virdunensis (BUVIGNIER) 0000 Agerinella lyraca PhTRULIUS

As for the other Central Dobrogean Upper Jurassic fa- cor a Ig a I fa c i es and Lu m i nil ami c r i tic I ago 0 n a I cies described by DRAGANESCU(1976), such as Gar a fa ci es, the brachiopods are almost completely lacking in Tärgusor triturated spongalgal facies, Piatra some facies, whereas in the other facies they occur only bioconstructed coralgal facies, Särtorman sparsely. It suggests paleoecological and sedimentologi- corpuscular algal facies, Furcil corpuscular cal conditions inimical to brachiopod-bearing benthic life.

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All the above-mentioned facies represented high-stress or The abandoned quarries from the Cekirgea valley dis- hostile depositional environments, characterized either play well-exposed and accessible stratigraphic sections bya high sedimentation rate and excessive hydrodynam- and thus afforded an excellent opportunity to examine the ics or by a muddy sedimentation lacking substrate firm- shell orientation pattern. The percentage of shells lying ness and, finally, by restrictive hypersaline conditions. parallel to the bedding plane and showing the pedicle Lastly, to evince once more the close biological affinity valve in lower position reaches around 50 % of the total. of the Central Dobrogean Upper Jurassic brachiopod- The remaining shells were noted either in oblique position, bearing benthic communities for some definite, open- with one of the valve looking to the bedding plane, or even marine, shallow-water biogenous carbonate facies, it is perpendicular to it, the latter position being commonly re- very interesting to note that the southward progressive mi- corded for rhynchonellids. All the above-mentioned styles gration of the main facies tracts on the Central Dobrogean of shell orientation clearly suggest no significant post- territory during the whole Middle Oxfordian to Early Kim- mortem movement of the shells, which are always articu- meridgian time interval, responsible for the marked dia- lated. chronism of the resultant facies belts paralleling a pre- Also, the analysis of the brachiopod distribution pattern sumable NW-SE depositional strike - these getting const- in the Topalu bioconstructed coralgal facies antly younger southwards, as DRÄGÄNESCU(1976) stated- obviously allows the major conclusion that the brachio- was concomitantly accompanied by a coincident south- pods appear to be typical life assemblages of unaltered ward migration with time of the brachiopod faunas and composition (biocoenosis), i.e. colonies of brachiopods their co-associated benthic organisms, normally with the which lived and have been fossilized in the same en- corresponding stratigraphic-induced, qualitative shifts in vironment, many individuals being apparently preserved their taxonomic composition. near to or in growth position. It is especially evident for The local distribution pattern of the Central Dobrogean some Juralina species, which share many individuals fre- Upper Jurassic brachiopods, within the definite biogen- quently found in vertical life position, the geopetal struc- ous carbonate facies, is highly variable being closely de- tures clearly accounting for it. Often, the anterior part of pendent" on the niche-size availability in certain benthic the shells are either empty or filled with sparry calcite, communities in a given bottom section. whereas the infilling carbonate sediment is limited only to Commonly, the Middle Oxfordian brachiopods appear the posterior part, thus testifying a semi-infaunallife-style as isolated individuals, such as in the Cekirgea stro- of the adult individuals of the Juralina species. matolitic algal facies from "La Vii" hill-section near Only occasionally in the fourth stromatolitic complex of Häri?ova town, also in the Vi sterna bioconstructed the Cekirgea Stromatolitic Algal Seriesexposed spongalgal facies, as it may be seen in several fossil along the Veriga Arm (Danube) cliff, southerly of the Ce- occurrences in the Casimcea Zone. These two facies of- kirgea valley mouth, the terebratulid brachiopods are fered numerous, isolated tiny niches to be settled by bra- overwhelmingly disarticulated valves and associated with chiopods. In some instances, brachiopods where ob- well-winnowed skeletal fragments of sponges and echi- served welded tangentially to the surface of several stro- noderms giving thin, discrete levels underlying the stro- matolitic laminae, presumably in apparent life position. In matolitic algal limestones. The large-sized, broken tere- other sections, the brachiopods are essentially patchy in bratulid shells are infilled by well-preserved, small-sized their distribution, being clustered in small pockets at sev- terebratulids. The essentially unsorted and unoriented eral distinct, laterally-continuous levels in the Middle Ox- material, strongly reworked but clearly indigenous, testi- fordian sponge-bearing stromatolitic algal facies from the fies a very shallow, high-energy, wave-abraded environ- Cekirgea valley, nearby its confluence with the Danube- ment, recurrently occurring within the long-lasting mod- Veriga Arm. It is a convincing evidence that the respective erate-energy environment enabling the flourishing of the brachiopods lived gregariously in small colonies. stromatolitic facies. The brachiopods in the uppermost Oxfordian Planula To conclude, alliines of evidence clearly prove that the Zone are frequently lying on and randomly oriented with brachiopod faunas environmentally confined to the regard to the bedding plane of the inter-reefal biodetrital above-described specific Central Dobrogean Upper and argillaceous limestones or dispersed around the Jurassic biogenous carbonate facies have to be regarded small-sized coralligenous buildups intertonguing in the as essentially autochthonous assemblages, mixing of fau- upper section of the Ce kir g e aSt rom at 0 lit i c A Ig a I nas derived from various habits prior to burial being com- Se r i es, whereas the Lower Kimmeridgian brachiopods pletely precluded. Obviously, most of the braChiopod are occurring in the free interstices between the arbores- yielded by the Central Dobrogean Upper Jurassic biogen- cent coral colonies forming the fourth coralligenous com- ous carbonate facies were buried at or close to their living plex outcropping along the Veriga Arm (Danube) cliff, sites. northwards of Topalu village, i.e. in the arborescent subfa- When comparing the Upper Jurassic brachiopod faunas eies of the Topalu Bioconstructed Coralgal from North Dobrogea with the coeval brachiopod faunas Se r i es. In all the above-described instances, as can be from Central Dobrogea, the drastic impoverishment of the interpreted from the sedimentary structures and tapho- former is strikingly evident (Text-Fig. 4, locs. 8 to 9). In all nomic features, the brachiopods appear to be essentially instances, the North Dobrogean brachiopod faunas ap- indigenous fossil assemblages without exotic elements. pear as essentially limited communities, showing con- Reworking, even if present, always went on in place. siderably reduced diversity, thus witnessing either unst- The shell orientation pattern in the rock is also very able or high-stress environments for the Upper Jurassic variable, reflecting either primary features or thanatocoe- depositional areas lying north of the Peceneaga-Camena nosis overprints. Fault. Even when studying smaller-sized populations, it is ob- For the brachiopod fauna included in the biodetrital vious that the brachiopod shells are currently lying at dif- limestones of the Cärjelari Formation in Sf ä n t a Fa eie s ferent angles to the bedding plane, in almost all investi- (Text-Fig. 3) there are several lines of compelling gated localities from Central Dobrogea. evidence, such as the wide size range of the shells repre-

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sented by juvenile through gerontic stages, therefore sug- aware that the percentage would undoubtedly vary with a gesting that there has been no selective transport of indi- more intense collecting in some occurrences, but we are viduals by current activity, also the relatively great propor- confident that the relative proportion would not change tion of disarticulated often fragmentary shells, all ac- significantly within individual communities. counting for a clear-cut allochthonous nature. The same Firstly, if we take into account the taxon number, it can aspects are shown by the associated bivalve and arthro- be stressed that the brachiopod communities from the pod faunas, both with disarticulated shells or carapaces. western part of the Central Oobrogean sector exhibit by far To put together such contrasting aspects, i.e. the essen- the highest taxonomic variety. Especially, plentiful bra- tially unsorted appearance and the high proportion of dis- chiopod communities flourished in the extreme shallow- articulated and fragmentary shells, a cohesive mass-flow water biogenous carbonate facies developing mainly in triggering mechanism should be inferred to conveniently the Cekirgea- Topalu sector (Text-Fig. 4, locs. 3 to 4) and explain the allochthony of the Cärjelari brachiopod-bear- subordinately in the Här~ova sector (Text-Fig. 4, locs. 1 ing fossil assemblage. The homogeneous and compatrio- to 2). tic, reduced taxonomic composition of the Cärjelari bra- Secondly, the brachiopod assemblages recorded in the chiopod fauna, at variance with a notable abundance of western part show not only a high taxonomic variety but individuals, suggests derivation from a population for also a remarkable individual abundance and high concen- which large numbers and localized extent represented ori- tration of some taxa making up the trophic nuclei in both ginal distributional features. Such a population, essential- the Cekirgea stromatolitic algal and Topalu ly opportunistic, was capable of rapid temporary expan- bioconstructed coralgal facies, thus accounting sion in size during short time intervals of stable carbonate for ample nutrient-supply and extensive firm substrate for sedimentation, although very restricted spatially to some attachment as well. small-sized, ephemeral submarine swells or to the upper When comparing the essentially coeval brachiopod fau- slope of their flanking fault-scarps, in an otherwise very nas of Vis t ern abi 0 con s t rue ted s p 0 n g a I g a I and tectonically-active setting, such as the Jurassic Pecenea- Ce kir g e ast rom at 0 lit i c a Ig a I fa eie s , the offshore ga-Camena transtensional basin. to inshore increase in both faunal diversity and density is The even much more impoverished brachiopod fauna fairly evident. It is customary to account for it by invoking yielded by the basinal cherty limestones of the Middle Ox- an increased food supply, because phytoplanktonic con- fordian Carabair Limestone (Text-Fig. 3) unambiguously centrations are often greatest in the inshore zones and reflects not only very limited settlement availability on a more plankton reaches the bottoms in shallower, higher- soft, deep-water muddy substrate, but especially a very agitated waters. limited food suply, relating to extremely quiet, poorly oxy- Also, from Text-Fig. 4 it may be observed that the Cen- genated waters bottom conditions. This conclusion is tral Dobrogean Upper Jurassic brachiopod communities supported by the fining and darker colour of sediments, recorded a pronounced overall rise in diversity and popu- the increase in organic matter, all accounting for the al- lation size during the Late Oxfordian time interval, thereby most complete lacking of suspension feeders and the ex- accounting for a maximum areal expansion of Dobrogean tensive burrowing by soft-bodied organisms. All these as- epeiric sea leading to an increased habitat heterogeneity. pects fairly well explain the overall reduction both in popu- Lastly, while emphasizing the dissimilarities in the en- lation and individual shell-size. vironment and the faunal composition, it is also worth not- ing the overall presence of some common and opportu- nistic brachiopods having the greatest ability to tolerate 5.2. Diversity and Density different facies conditions. However, as already men- tioned in the foregoing section, the brachiopod commu- The taxonomic variety and individual characteristics of nities environmentally-confined to the major Central 00- the Oobrogean Upper Jurassic brachiopods will be dealt brogean Upper Jurassic biogenous carbonate facies are with both qualitatively and quantitatively in terms of facies distinguished by their distinct key species and trophic dependance. nuclei. When counting the specimen number per species, Text-Fig. 4, depicting the proportional share of both in- often one single species is dominant within the individual dividual species and higher rank taxa within the whole fau- brachiopod communities, almost in every locality and na in every Dobrogean Upper Jurassic shallow-water stratigraphic level. When two or more species have a simi- biogenous carbonate facies, displays the marked, geo- lar abundance, they currently belong to different genera. graphically-varying diversity and density of the associ- The Vi stern abi 0 c on st ru cted s p on g a Ig a I fa- ated brachiopod faunas. As already emphasized, in some eie s bears two brachiopod assemblages which markedly instances, such as for the upper sections of the Ce- differ in faunal emphasis, being stratigraphically and en- kirgea and Visterna facies series, the excessive vironmentally constrained to the lower, Middle Oxfordian taxonomic composition of the brachiopod assemblages Bio s t rom a I Com pie x, characterized by less-diversi- unambiguously reflects the existence of several distinct fied brachiopod communities (Text-Fig. 4, locs. 5 to 6) trophic associations within these major facies series. and, respectively, to the higher, Upper Oxfordian Their more detailed knowledge needs further study. That Biohermal Complex, characterized bya much more is why the present survey is merely concerned with the diversified brachiopod community (Text-Fig. 4, loc. 7). global pattern of diversity and density in each major bra- The main controlling factors refer to niche-size availability chiopod-bearing facies series. and trophic amensalism relationships which became Although no special sampling was done in the field to more favourable upwards. Whereas the Middle Oxfordian determine the faunal composition in definite facies and brachiopod communities were numerically dominated by localities, the brachiopods in collections are present in Terebratulidae and Wellerellidae, theotherfa- sufficient numbers to make fairly accurate general com- milies (Oimerellidae, Pygopidae, Zeillerii- ments with regard to fossil communities and to assess the da e) are almost equally represented, or preferentially oc- major differences between them. Certainly, we are fully curring (Rhynchonellidae). The Upper Oxfordian

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brachiopod community records the major occurrence of tionofthe Cekirgea stromatolitic algal facies.lt both Cranidae and Dallinidae, reaching together is strikingly correlating with the highest taxonomic variety upt050 %ofthetotal,theenteringof Dictyothiridae known for the Central Dobrogean Upper Jurassic brachio- besides the constant occurrence of Well ere II id a e , pod faunas, thus reflecting the existence of very diversi- both with a participation ranging between 10 and 18 %, to fied environmental-facial conditions within the stromato- the major prejudice of Terebratulidae and Rhyn- litic algal facies during the Late Oxfordian in the Ce- eh 0 n e II i d a e, which form no more than minor constitu- kirgea- Topalu sector. Consequently, the brachiopod as- ents in the fossil assemblages. semblage yielded by the upper section of the Ce kir ge a The key species in the Vi sterna bioconstructed fa eie sse r i e s includes brachiopods belonging to very s p 0 n g a I g a I fa eie s are represented by Argovithyris different trophic associations, environmentally-confined stockari, Septaliphoria sancteclarae and Nucleata nucleata in the to reefal, peri- and inter-reefal, or stromatolitic subfacies. Middle Oxfordian Biostromal Complex (Text-Fig. 4, Looking at it as a whole, the trophic nucleus is overwhelm- loc. 5), whereas Ismenia pectunculoides and Terebratulina (Crura- ingly dominated by Terebratulina (Cruralina) substriata and some lina) substriata alongside several species of Trigonellina, species of Moeschia, Juralina and Dorsoplicathyris, such as M. among which T. intercostata and T. loricala are the most com- granulata, J. bullingdonensis and D. sp. mon, make up an enlarged trophic nucleus in the brachio- Lastly, it is noteworthy for the Cekirgea- Topalu sector, pod fauna of the Upper Oxfordian Bio her m a I Com- the brachiopod faunas straddling the boundary between pie x. If we compare the two brachiopod assemblages Late Oxfordian and Early Kimmeridgian underwent a yielded by the Middle Oxfordian Bio s t rom a I Com- marked decline upwards, so as in the fourth coralligenous pie x (Text-Fig. 4, loc. 5 vS. loc. 6), there are little qualita- level, i.e. in the lower arborescent coralgal subfacies of tive differences between the two localities. The striking the To p a I ubi 0 con s t rue ted cor a I g a I fa c i es, the difference is not likely to be due to the difference in taxon- brachiopod/coral ratio is clearly less than 1, as a result of a omic level, but mainly to the relative participation of the progressive process of shallowing and shoaling upwards species. Lastly, in comparing the brachiopod faunas of the in response to the overall regional regression of the Central two subfacies in the Vi sterna bioconstructed Dobrogean Upper Jurassic epicontinental sea. spongalgal facies it should be kept in mind that the extreme diversity of the brachiopod fauna in the Text-Fig. 5 clearly demonstrates the inverse trending in Bio her m a I Com pie x, which shares a great mixture of temporal changes in the taxonomic composition of con- taxa, obviously reflects the existence of several, though temporaneous coral and brachiopod faunas, respectively, poorly defined, trophic associations, it being undoubtedly during Late Oxfordian to Early Kimmeridgian time interval. related to the availability of very diversified favourable Seemingly, it suggests that the biologic competition be- niches in the spongalagal biohermal buildups. tween coral communities and other benthic organisms As for the brachiopod communities occurring in the may have played a major role in diminishing the diversity of Cekirgea stromatolitic algal facies, the over- brachiopod faunas. In the arborescent coralgal subfacies whelming participation of Te re bra tu lid ae is to be no- of the Topalu bioconstructed coralgal facies, ticed, heading in almost alilocalities to around 50 % ofthe although the rhynchonellids are exceedingly outnum- total, being followed at a greater distance by Rh Y n c h 0- bered by the terebratulids in proportion of 1:5, the key nellidae.lnthe Cekirgea sponge-bearing stro- species is however represented bya rhynchonellid, i.e. by matolitic subfacies (Text-Fig. 4, loco 3) the brachio- Torquirhynchia speciosa. The trophic nucleus also includes pod community is numerically dominated by far by Lacu- numerous species of Juralina, among which J. topalensis is nasella cracoviensis and Moeschia alata, which highly outnumb- the most prevalent by far, alongside the increasing partici- er other species showing also important participations, pation of zeilleriids which reach up to 20 % of the total. such as Placothyris carsiensis, Ismenia pectunculoides and Zeilleri- Northwards, in the Här~ova zone (Text-Fig. 4, locs. 1 to na delemontana. 2), the brachiopod faunas occurring in the Ce k i rg e a fa- On the other hand, it is noticeable that a marked strati- ci e sse r i e s are drastically diminishing both in taxon- graphic shift in taxonomic composition and diversity is re- omic composition and individual abundance, the relative corded throughout the Upper Oxfordian rock-sequence importance of key species being also modified, reflecting outcropping along the Veriga Arm (Danube) cliff when the important changes of depositional environments north of coralligenous buildups are interleaving in the upper sec- Cekirgea- Topalu area.

Text-Fig. 4...... Areal distribution pattern and Quantitative paleobiocoenotic analysis of Upper Jurassic brachiopod assemblages from Central and North Dobrogea. Circles: Taxonomic composition of the brachiopod faunas (families). Histograms: Number of specimens. Locality index: 1-2 = "La Vii" hill, north of Här~ova; 3 = Cekirgea valley; 4 = Veriga Arm (Danube) cliff, north of Topalu; 5 = Särtorman valley; 6 = Casimcea valley; 7 = Visterna valley; 8 = Cärjelari; 9 = Dunava\u de Jos. Family-symbol key: 1 = Cranidae; 2 = Dimerellidae; 3 = Wellerellidae; 4 = Rhynchonellidae; 5 = Terebratulidae; 6 = Dictyothyridae; 7 = Pygopidae; 8 = Zeilleridae; 9 = Cancellothyrididae; 10= Dallinidae; 11 = Thecideidae. Facies series-symbol key: a = Visterna Bioconstructed Spongalgal Series, Biostromal Complex; b = Visterna Bioconstructed Spongalgal Series, Biohermal Complex; c = Cekirgea Stromatolitic Algal Series, sponge-bearing lower complex; d = Cekirgea Stromatolitic Algal Series, coral patch reef-bearing upper complex; e = Topalu Bioconstructed Coralgal Series; f = Cärjelari Formation, biodetritallimestones; 9 = Carabair Limestone, basinal limestones. Species-symbol key: A = Aulaeothyris sp.; Ab = Argovithyris baugieri; Ast = A. stoekari; Ag = Agerinella lyrata; As = Aeanthorhynehia spinulosa; Ase = A. sentieosa; Cf = Cheirothyris f1eurieusa; CI = Crania lamel/osa; Cli = C. lineata; Clv = C. laevissima; Crs = Craniseus suevieus; Cs = Terebratulina (Cruralina) substriata; Di = Oigonel/a sp.; Df = Oorsoplieathyris lareinata; Dp = O. petersi; D = O. sp.; Dk = Oietyothyris kurii; Ip = Ismenia peetuneuloides; Jb = Juratina bullingdonensis; Jc = J. easteltensis; Jk = J. kokkoziensis; Js = J. subformosa; Jt = J. topalensis; J = J. sp.; La = Lacunosetla arotiea; Lc = L. eraeoviensis; Ls = L. sparsieosta; LI = L. tritobataeformis; L = L. sp.; Ma = Moesehia alata; Mg = M. granulata; Mz = M. zieteni; M = M. sp.; Mc = Montielarel/a ezenstoehowiensis; Mr = M. rollieri; Ms = M. strioptieata; Mt = M. triloboides; Nn = Nueteata nueleata; Pc = Ptacothyris earsiensis; P = P. sp.; Rv = Rioultina virdunensis; Sm = Septatiphoria moraviea; Sp = S. pinguis; S = S. sp.; Ss = Septocrurel/a saneteelarae; Ta = Torquirhynehia astieriformis; Ts = T. speeiosa; Td = "Terebratula" dobrogensis; Ti = Trigonellina intereostata; TI = T. lorieata; Tp = T. peetuneulus; Tl = T. trimedia; Zd = Zeillerina delemontana; Z = Z. sp.; 0 = others.

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markably increasing. Although several brachiopods, such OXFORDIAN KIMMERIO. as Moesehia a/ata, Terebratu/ina (Crura/ina) substriata, /smenia pee- LOWER MIDDLE UPPER LOWER tuneu/oides, Jura/ina topa/ensis or "Terebratu/a" dobrogensis are long-ranging species, each of them currently shows a BIOCONST RUCTE 0 UPPER BIOCONSTR. SPONGAlGAl SERIES CORAlGAl SERIES preference for a definite facies, where they occur in great IV abundance and high concentration, commonly represent- II III ing the key species in the respective facies. Lastly, the Up- per Oxfordian-Lower Kimmeridgian brachiopod assem- 70 brachiopods ,..... blages in Central Dobrogea record an outstanding spe- corals , , cies-lineage of Jura/ina, which exhibits an increasing spe- - - -- I \ , cies diversity and abundance upwards from the Ce- 60 I , I \ kirgea facies seriestothe Topalu facies series, I , 50 I , where Jura/ina species exceedingly dominate the other bra- I \ I , chiopods in total number of individuals. I I Taking into account the Upper Jurassic brachiopod fau- 40 I I I I nas from North Dobrogea, the diversity drops dramatically , I 30 I I north of Peceneaga-Camena Fault, thus enhancing so ,I , much the more the gradient of diversity decline when go- I 20 ,-- \, ing from the Här:;;ova area towards the North Dobrogea. , The Middle Oxfordian brachiopod fauna of the Cärjelari I \, 10 ,,-'" , Formation in Sf ä n t a Fa eie s, although extremely re- , duced in taxonomic diversity (Text-Fig. 4, loc. 8). shares in ,...'" turn a relative great abundance of the Te re bra t u I i- Text-Fig. 5. dae, which overshadowed the Rhynchonellidae Stratigraphic distribution of brachiopod VS. coral species in the Upper and Z e ill e r i i d a e. To account for this major decline in Oxfordian-lower Kimmeridgian rock-sequence from Veriga Arm (Danube) cliff, north of Topalu. diversity, it should be noted that faunas in the unstable 1-111= coralligenous levels in Cekirgea Stromatolitic Algal Series; IV = environment are always subject to high stress and accord- Topalu Bioconstructed Coralgal Series ("Topalu reef"). ingly restricted to eurytopic organisms showing low di- versity. Furthermore, the brachiopod fauna delivered by The brachiopod faunas occurring in the two subfacies the Middle Oxfordian Carabair Limestone is even much ofthe Cekirgea stromatolitic algal facies in the more sharply restrained both in high rank taxa and species "La Vii" hill-rock sequence show a considerably reduced number,the Wellerellidaeand Dimerellidaeplay- diversity and they are usually strongly dominated by few ing an equal role (Text-Fig. 4, loc. 9). In the last case, the taxa. Thus, whereas the Moesehia a/ata is the dominant spe- extreme reduction in population size was related to the ciesintheMiddleOxfordian Cekirgea sponge-bear- problem of colonizing a muddy substrate and disparities ing stromatolitic subfacies, Terebratu/ina (Crura/ina) in food distribution. The only available firm surfaces for substriata, although having a predominance over /smenia pee- attachment were provided either by the ammonite shells tuneu/oides, both strongly dominate all the remaining spe- or by some non-preservable, firm organic substrate, e.g. cies in the Upper Oxfordian-Lower Kimmeridgian Ce- seaweed fronds, the latter situation implying an epiplank- kirgea stromatolitic-coralligenous subfa- tonic life-style for the only two species being in the fauna, eie s. Generally, our available data clearly indicate a gra- Montie/are//a ezenstoehowiensis and Laeunose//a sparsieosta, at dient in diversity decline of brachiopod faunas from south least for the larval stage. to north on the territory of the Central Dobrogean sector. In some particular situations, the high diversity is not matched by a corresponding high density. For instance, in the brachiopod faunas yielded by the Bio her m a I Com- 5.3. Size-Frequency Distribution pie x of the Vis t ern abi 0 con s t rue ted s p 0 n g a Ig a I With regard to this parameter, which primarily reflects fa eie s (Text-Fig. 4, loc. 7), although one of the most di- the quality of the life habits, there is a wide range of indi- versified among the Central Dobrogean Upper Jurassic vidual size, from millimetric specimens, as for the C ran i- brachiopod faunas, most of the species occur in low dae, Thecideidae, Wellerellidae, Trigonel- numbers. A similar share is characterizing the Ce kir g e a linae and some Rhynchonellidae(Montie/are//a), up stromatol it ic al gal fac i es developing in the Här:;;ova to 70 mm for some specimens of Moesehia, Jura/ina, Torquir- area (Text-Fig. 4, locs. 1 to 2). hynehia and Septa/iphoria. As already emphasized, the major Central Dobrogean A clear-cut shell size-variation can also be found in point Upper Jurassic brachiopod paleocommunities, although of ontogenetic development. There are species for which environmentally distinct, currently include many cosmo- large-sized adults are commonly recorded, such as Moe- politan or long-ranging brachiopods. Thus, the Z e ill e- schia granu/ata, Jura/ina sub/ormosa, J. kokkoziensis, Dorsop/iea- r i i d a e, maybe eurytopic organisms, are found in almost thyris fareinata, Torquirhynehia speciosa, Septaliphoria moraviea, all the brachiopod assemblages, thus proving a wider whereas for other species the dwarfism is fairly obvious, range of tolerance for varied sedimentary environments. such as for Argovithyris baugieri. This large variation in shell They are commonly conspicuous in the moderate-energy size was closely related to niche size in a specific facies or Cekirgea stromatolitic algal facies, where Zei/- due to some high-stress physical factors influencing /erina de/emontana shows a notable abundance of indi- growth patterns, e.g. lowered contents of dissolved ox- viduals, and, respectively, in the very shallow-water, high- ygen, reduced food supply or variable salinity. It is con- -energy Topalu arborescent coralgal subfa- spicuous that adult shells of small physical size are domi- eie s , where the total occurrence of Zeillerina species is re- nantly occurring in the protected quiet, shallow-water de-

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positional environment of the Vi s t ern abi 0 con- The amount of broken or deformed shells is fairly moder- structed spongalgal facies (Text-Fig. 2 S, facies II ate and mainly ascribed either to deformation after burial a-b), where the patelliform sponges provided also very ti- or to sampling operations. For instance, in the western ny bottom niches for other benthic organisms. Commonly, part of the Central Dobrogean sector the deformation af- niche-size diminishing enhanced the trophic amensalism fected especially the brachiopods included in the thin- relationships in suspension-feeding benthic communi- bedded argillaceous limestones intercalated between the ties, by introducing strong interspecific competition be- first and second coralligenous levels from the Veriga se- tween organisms requiring equivalent food resources. quence, interleaved in the upper section of the Ce- That is why the Piatra bioconstructed coralgal kirgea facies series. Not only the large-sized speci- fa eie s bearing crustiform colonies is completely barren mens of Dorsoplicathyris, Juralina, Zeillerina but also the small- of brachiopods owing to any niche partitioning. sized specimens of Terebratulina are crushed or completely On the contrary, both the Cekirgea stromatolitic flattened owing either to sediment surcharge or to com- a Ig a I fa eie s and the To p a I ubi 0 con s t rue ted paction during lithification. Especially, the deformation cor a Ig a I fa eie s provided the best sites for brachiopod may be explained by the patch-reef overloading causing settlement, within which large-sized specimens are very differential compaction of the underlying deposits. Also, abundant (Text-Fig. 2 A, facies II and V), thus proving the in the Middle Oxfordian spongalgallimestones of Vi s t e r- presence of the most favourable conditions, i.e. well-agit- n a fa eie sse r i es from Casimcea Zone a high number of ated waters by currents and waves, ample food supply the large-sized terebratulids and rhynchonellids reveal and extensive firm substrates available for larval attach- post-mortem deformation with changing in outline and ment. size. Some are chipped but the fragments remained yet in Very interesting is also the shell size-variation in the connexion. Lastly, though the brachiopods delivered by stratigraphic record. Generally, the very scattered Lower the reefal coralligenous limestones show a very good Oxfordian brachiopods have smaller sizes as compared state of preservation, a large number of Juralina specimens with the congeneric Middle Oxfordian brachiopods, such were often damaged during freeing from matrix, the high as Moeschia and Placothyris. A spectacular size growth is typ- umbo or the empty anterior part being currently broken. ical of the uppermost Oxfordian-Lower Kimmeridgian bra- On the other hand, there are some types of deforma- chiopods (Text-Fig. 2 A, facies V), which was coincidental tions which were clearly achieved during life time. It is es- with the appearance and development of the very shal- pecially worth noting the particular case of some speci- low-water arborescent coralligenous facies, for which the mens of Moeschia, Dorsoplicathyris and Juralina, which display trophic resources stability and higher energy environment growth irregularities achieved during life, such as slight represented the fundamental ecologically governing asymmetries and the uneven development of growth lines, factors. due to crowding during growth in high-concentrated For North Dobrogea a major distinction exists between "cluster-like" associations, which is consistent with an oy- the brachiopod faunas from the Cärjelari and Dunavä~u de ster-like gregarious life-style. Jos localities. At Cärjelari, the brachiopod assemblage in- The excellent state of preservation is especially obvious cludes specimens of wide size range, e.g. Torquirhynchia as- for the small-sized, partially or wholly silicified Upper Ox- tieriformis (PI.I, Figs. 6-10), which is in good accordance fordian brachiopods sieved from the cave-residual clays with its allochthonous origin by cohesive debris flow re- resulting from weathering of Vi stern a facies seri es, working, also explaining the poor sorting, the high degree which share a remarkable freshness both for C ran i d a e of disarticulation and fragmentation of the shelly faunas. and The eid eid a e, thus suggesting quiet shallow-wa- In exchange, at Dunavä~u de Jos, all specimens recovered ter conditions and rapid burial. Though frequently disar- from the basinal Carabair Limestone are represented only ticulated, the shells bear no evidence of transport prior to by almost equal, small-sized « 1 em in length), presum- burial, the disarticulation being likely related to etching ably either immature or dwarfed individuals (Text-Fig. 3 S; out by chemical weathering. The best state of preserva- PI. 1, Figs. 1-5). Obviously, the generalized reduction tion is shown however by the brachiopods collected from both in population and individual shell size in the deep- the stromatolitic algal limestones occurring in the Ce- water muddy environments can be accounted for most kirgea valley, near its confluence with the Danube-Veriga plausibly by a sharp decline in food supply. Arm. The faint growth-lines and all elements of the umbon- al area, such as beak-ridges, pedicle foramen, as well as all details of deltidium are very well-preserved. The fine ornamental elements of Acanthorhynchia species, such as 5.4. Preservation State the delicate spines on the rib crests of the lateral areas, The analysis of this parameter is required by the neces- and also the granular reticulate ornamentation of Dic- sity to assess thanatocoenosis overprints when trying to tyothyris kurri, both taxa being represented by small-sized, delineate some original paleoecological features, such as thin-shelled specimens, are key indicators proving the ex- the amount of disarticulation or the degree of reworking istence of some sheltered niches within the Ce k i rg e a and of exotic admixture of the faunal assemblages. stromatolitic algal facies. Most of the Central Dobrogean Upper Jurassic brachio- As for North Dobrogea, two extreme situations are to be pod faunas show a very good state of preservation. The found. Firstly, a high degree of post-mortem disarticula- percentage of disarticulated valves is extremely reduced tion is particularly characteristic for the Cärjelari brachio- in both the Ceki rgea and Topal u fac i es seri es .It is pod fauna, within which more than 30 % of the total num- inferred from the sedimentary aspects and paleoecolo- ber of specimens were embedded as disarticulated val- gic-taphonomic features that most of the recovered speci- ves, often as fragments, thus accounting for a very dy- mens were preserved in what was clearly the life habit, namic sedimentation in the tectonically-active Pecenea- post-mortem reworking and mixing of fossil assemblages ga-Camena transtensile basin. Secondly, the small-sized being completely precluded. brachiopod faunule of Dunavä~u de Jas area, though very

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deformed after burial, being either stretched, flattened or Central Poland by WIERZBOWSKI(1970). Owing to the high crushed, remained essentially articulated, a primary asymmetric, globose outline, the adult individuals of this feature testifying extreme quiet waters bottom conditions species have been formerly assigned by SIMIONESCU(1910 for the deposition of Carabair Limestone. b) to "Rhynchonella inconslans Sow.", a species now referred to Torquirhynchia. At present, it is clearly demonstrated that T. inconslans has no confirmed record in Central Dobrogea, 5.5. Brachiopod Morphology this species commonly occurring in the Lower Kimmeridg- in Response to Environmental Factors ian biogenous facies from NW Europe. Instead, other spe- cies of Torquirhynchia are occurring in Central Dobrogea, es- The brachiopods, which are marine, epibenthic, sus- sentially coeval with L. cracoviensis and showing strong ho- pension-feeding and sessile-pivoting, generally pedical- meomorphy in external morphology with the latter. It is Iy-attached organisms, are highly dependent on the en- mainly the long-ranging T. speciosa occurring both in the vironmental factors. It is especially the external morpho- UpperOxfordian Cekirgea stromatolitic algal fa- logy and frequently the internal structure which are closely eies and the Lower Kimmeridgian To pa lu bio c on- adapted to these factors. Always, the morphological ad- structed coralgal facies (Text-Fig. 2 A, facies II and aptations of brachiopods have been oriented on the per- V). However, it should be stressed that although by its fect utilisation of sources in any niche. asymmetry Lacunosella cracoviensis is highly homeomorphic Some Dobrogean Upper Jurassic brachiopod genera with some species of Torquirhynchia, the style of ornamenta- and species are particularly interesting by their constant tion is very different. Whereas the former shares both preference for some facies, to which they adapted the bifurcate and intercalatory ribs, the latter share only morphology. For instance, Lacunosella, although recorded simple ribbing. Though the reason of this odd developing in most of the Dobrogean Upper Jurassic brachiopod of shells to Lacunosella cracoviensis cannot be conveniently communities, shares a higher frequency in the Middle and explained, CHILDS (1969) considers that undoubtedly in Upper Oxfordian sponge-bearing carbonate buildups re- the case of asymmetric shells the exaggerating growth of lating to Visterna facies series and, respectively, to the brachial valve currently determined a corresponding Cekirgea facies series. The massive shells, often reduction in size of the pedicle valve. It has been custom- showing an asymmetric outline, and the persistent for- ary to think that these asymmetrical adult individuals of amen, testifying a functional pedicle muscle in the adult Lacunosella and Torquirhynchia were always able to maintain stage, all seem to indicate high adaptive strategies of this the same configuration of the anterior commissure when genus to the main environmental factors controlling the reversing the living position of shells. As a result, an in- development of sponge-bearing carbonate buildups, i.e. creasing chance could be achieved in the successful ad- moderately- to highly-agitated waters by currents and aptive strategy of these species in response to some high- waves, ample food supply and extensive firm substrates -stress physical environmental factors, especially in re- for attachment. Although the remarkable co-occurrence sponse to an increasing rate of sedimentation, by allowing of Lacunose//a cracoviensis and sponges was already emphas- both the left and the right lobes of the mantle cavity to ized by QUENSTEDT(1871), WISNIEWSKA(1932) and AGER remain physiologically independent. For T. speciosa occur- (1965), it is not yet clear why this species restricted its ring in the Topalu arborescent coralgal subfa- preference for the sponge-bearing carbonate buildups eies (Text-Fig. 2 A, facies V; PI. 2, Figs. 12-13), the in- and what special advantage they could have from it dependence of the two lateral mantle lobes was even more (CHILDS, 1969). In our opinion, it may reflect a raised enhanced by the intervention of a well-developed sulcus. potential of this species for high utilisation of living Finally, it seems likely that in response to similar environ- spaces provided by the spongalgal buildups. mental factors all these homeomorphic brachiopods Montic/arella is another genus frequently recorded in the should be obliged to develop hydrodynamically stable Middle and Upper Oxfordian sponge-bearing carbonate shells which commonly show comparable shell deforma- buildups. In opposition to Lacunosella, the small-sized and tion resulting from burial in living position. the delicate shells of Monlic/arella species suggest either an Torquirhynchia astieriformis (PI. 1, Figs. 6-10), occurring in epiplanktonic life style, being pendant to non-calcareous the Middle Oxfordian brachiopod fauna of the Cärjelari algae fronds, or a more reduced chance in the interspeci- Formation in Sfänta Facies, shares also strong, simi- fic competition for niche settlement. lar asymmetric outline for the adult individuals. However, Some terebratulids, frequently associated either to the when studying the ontogenetic development of this spe- Vi sterna bioconstructed spongalgal facies or cies, for which convenient material exists, it is clear that to the Cekirgea sponge-bearing stromatolitic the juveniles show more or less rectimarginate or low uni- a I g a I sub f a eie s, such as Moeschia a/ala, Argovilhyris plicate anterior commissure. These extremely-differing slockari, A. baugieri and P/acolhyris carsiensis, although very dif- ontogenetic development stages were undoubtedly re- fering in size, all exhibit some homeomorphic features in lated to a reclining ambitopic behaviour, the juveniles hav- their external morphology (Text-Fig. 2), while the internal ing a pendant life-style whereas the adults were able to structures are clearly differing, especially for P/acolhyris. live free on mobile substrates. Their nearly flat brachial valves and the uniplicate or In both uppermost Oxfordian Ce k i rg e ast ro m a to I i- slightly sulcate anterior commissure suggest, in the opin- tic - cora II i g en 0 u s s u bfac i es and Lower Kimmerid- ion of BOULLIER(1976), that the individuals of these spe- gian Topalu arborescent coralgal subfacies cies were either directly lying on the substrate or sus- (Text-Fig. 4, loc. 4 - OX3 and km1 ), the trophic nuclei in- pended along the brachial valve. clude, besides T. speciosa as key species, a very abundant Another very interesting case of homeomorphy is that of population of varied species of Jura/ina, such as J. lopalensis, Lacunosella cracoviensis which exhibits a luxuriant abund- J. kokkoziensis, J. caslellensis, J. subformosa and J. bullingdonensis. ance in the Middle and Upper Oxfordian Cekirgea By their large-sized and thick, slightly convex shells, bear- sponge-bearing stromatolitic algal subfa- ing either rectimarginate or low uniplicate anterior com- eie s, a situation very comparable with that recognized in missure and a large foramen devoid of beak-ridges, thus

64 ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at testifying a strong functional pedicle muscle throughout as forams, bryozoans, worms, bivalves, gastropods, ce- life, the Jura/ina population adopted a successful morpho- phalopods, crustaceans, crinoids and echinoids, making logical adaptive strategy for the highly, wave- and cur- up plurispecific fossiliferous taphocoenosis. rent-agitated reefal and peri-reefal environments, as it Some very interesting, direct trophic relationships were was already emphasized by AGER(1965), CHILDS(1969) established between the brachiopods and other epifaunal and SOULLIER(1976). Some species of Juralina occurring in organisms from the above-quoted groups, the brachio- the Topalu arborescent coralgal subfacies, i.e. pods suitably providing firm support for some epibionts. the thick-shelled J. kokkoziensis, J. topa/ensis and J. subformosa On the other hand, the brachiopods themselves exhibit (Text-Fig. 2 A, facies V), are provided with a high, erect permanent or temporary epizoic behaviour. beak and a very developed deltidium, which warrants a In the Cekirgea stromatolitic algal facies the semi-infaunallife-style on mobile, bioclastic sandy sedi- epifauna encrusting the terebratulid shells (Moeschia spp.) ments of these brachiopods living in the high-energy includes foliaceous bryozoans (P/agioecia), serpulid worms coralligenous environments. It is the thick callus of the and frequent bivalves (Athreta, Ostrea). The epizoans are al- umbonal internal side which led to the overweighting of ways encrusted towards the periphery of the valves. As the posterior part of the shells, thus enabling a much more these did not mould over the commissure and also did not efficient anchorage of these heavy, thick-shelled bra- overgrow the pedicle foramen, it is clear that the brachio- chiopods. Sy their large-sized shells, all these species of pods were living during the settlement and growth of the Jura/ina provide strong evidence that the arborescent- above-mentioned epifaunas. Also, multiple generations of coralligenous environment was very favourable for their epizoans have not been identified, and only two of the development. Seemingly, the varied Jura/ina species, like- above-mentioned epibiontic organisms are occasionaly wise those of Torquirhynchia, were largely reclining ambitop- attached on the same valve. These findings and the re- ic organisms, being essentially dependent on a hard site duced sizes of the epizoans suggest that the brachiopods for larval attachment but then able to grow out freely over remained unburied only a short time after their death. The mobile, bioclastic sandy substrates in adult stages, so as rhynchonellid shells are sparsely encrusted by epizoans, to exploit successfully the living spaces between the ar- particularly by oysters and serpulid worms. borescent coral colonies. As to the epizoic attachment of brachiopods on the or- Lastly, by their external morphology, some species of ganic substrate, the intimate relationships between some Jura/ina from the Central Dobrogean Upper Oxfordian- brachiopods (Lacunosella, Montic/arella) and sponges were al- Lower Kimmeridgian biogenous carbonate facies are also ready discussed in the foregoing section of the present diachronously homeomorphic with some brachiopods paper. The preferential attachment of era ni d a e and commonly occurring in the Kimmeridgian and Tithonian The eid eid a e on sponges and corals is also clearly es- ~tramberk-type cora,lIigenous facies of the Carpathians tablished. The undersides of patelliform sponges from the regions, e.g. with the varied Upper Tithonian species of Vis t ern abi 0 con s t rue ted s p 0 n g a Ig a I fa eie s are Tropeothyris described by SMIRNOVA(1975) in the Polish Car- encrusted with thecideids (Rioultina), besides serpulid pathians (Inwald). worms (Serpu/a f1accida, S, gordialis, S, tricarinata), bryozoans Therefore, it is worth mentioning that all the above-men- (P/agioecia, Stromatapara, Ceriocava), calcisponges (Neuropara). tioned cases of homeomorphy characterizing several bra- On the contrary, the uppersides are covered by relatively Chiopods commonly occurring in the Central Dobrogean thick algal coatings. The "triptych" given by the co-occur- Upper Jurassic biogenous carbonate facies highly con- rence of thecideids, serpulids and bryozoans, as already firm the finding that both sponge- and coral-bearing reefal reported by GAILLARD(1971, 1983) and PAJAUD(1974), was facies constrained the opportunistic brachiopods to dependent on two major ecologically-limiting factors for adopt some convergency in their external morphology, re- growth, i.e. the substrate and the light, whereas the colon- gardless of their differing stratigraphic occurrence, so as ization by the blue-green algae on the uppersides of patel- to efficiently exploit the niche space and food resources in liform sponges was determined by the need to use for moderate- to high-energy environments. However, for all growth the reduced light which penetrates down to 50 m, the above-described examples, the interpretation of the representing the lower limit of depth range required as op- adaptive responses in the functional morphology requires timal for the development of sponge bioherms. further study. The "gallery" organisms included in the above-men- The brachiopod fauna of Dunavatu de Jos is currently tioned "triptych" were most likely either sciaphilic or much composed of small-sized, simple-ornated Lacunosella spar- more tolerant in point of light requirements. This great tol- sicosta bearing deep-sulcate pedicle valves, such a morph- erance is proved by the fact that many of the species of ology being very advantageous in quiet deep-water en- Cranidae, Thecideidae and Terebratellidae vironments with very limited food supply. The deep sinus recorded in the Vis t ern a fa eie sse r i e s were also of the anterior margin of the pedicle valve increased the cited by SARCZYK(1970) in the biogenous facies bearing divergence between the inhalant and exhalant feeding- ramose corals and bryozoans from Saltow (Poland). This currents and assured a high utilisation of suspended or- author already emphasized the close resemblance of the ganic matter. Saltow brachiopod assemblage with those from Visterna valley. A similar fossil assemblage, including C ran i d a e, Thecideidae and Terebratellidae, occur in the 5.6. Brachiopod Relationships western part of Central Dobrogea in the second coralligen- with Other Benthic Organisms ous level interleaved within the upper section of the Ce- kirgea facies series. In the Upper Jurassic brachiopod-bearing biogenous The coincident occurrence of the above-mentioned bra- facies from Central Dobrogea, besides the major inverte- chiopod groups, with many common elements at the gen- brates contributing to the biogenous carbonate facies as eric and species level, both in the spongieric and coral- pivotal frame-builders, such as algae, sponges and Iigenous buildups accounts for the much larger ecologic corals, several other organisms are also represented, such tolerance for the light factor of these cavity-dwelling bra-

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chiopods. Obviously, the colonization of the undersides of However, whereas the high diversity and density of the patelliform sponges by the foregoing mentioned epizoan Upper Jurassic brachiopod faunas from the Central 00- organisms was due mainly to the algae concurrence, brogea are highly suitable for a reliable paleobiogeo- which, requiring agitated-water conditions in the photic graphic analysis, conversely, for the coeval brachiopod zone, settled efficiently the uppersides of patelliform faunas from Dunavatu de Jos locality in North Dobrogea it sponges during the competition for substrate. On the is not possible to have a similar confidence in delineating other hand, one can expect that the preferential settle- the paleobiogeographic affiliation due to a very impover- ment of filamentous algae on the uppersides of patelliform ished occurrence. sponges was the consequence of mutually-profitable On the other hand, it should be noted that while extens- symbiotic relationships with host sponges. It is thought ive paleobiogeographic analyses have been carried out for that by photosynthesis the algae may provide oxygen and the European Lower and Middle Jurassic brachiopod photosynthetically-derived products to the host, remove faunas, little attention has been paid to the compatriotic carbon dioxide and waste products or be instrumental in Upper Jurassic brachiopod faunas, except those of the providing protective colouring. It was already proved that Tithonian. As a result we have felt the absence of relevant the symbiosis of different frame-building organisms with studies, wherein to integrate our results. Furthermore, the photosynthesizing algae is especially convenient for the terminology used by different authors in naming the paleo- host organisms by enhancing rates of skeletogenesis biogeographic units, more or less overlapping in scope, is (TALENT,1988). profusely expanded, and very differing not only for varied Lastly, when referring to the coral/brachiopod ratio in time intervals of the Jurassic Period but also for different the coralligenous buildups occurring in the Ce kir g e a groups of organisms. As for the European Jurassic bra- sponge-bearing stromatolitic algal subfa- chiopod provinciality the following bioprovinces are curr- eie s, it is noticeable that the upward increase in the taxo- ently in usage: the NW-European province vs. the Mediter- nomic composition and abundance of the coral faunas ranean province, for the Early and Middle Jurassic time was concomitantly accompanied by a progressive decline interval (AGER,1967, 1971; VÖRÖS,1977, 1984, 1988, 1993), in brachiopod population size and also in number of spe- and Boreal, Sub-Mediterranean (Sub-Tethyan or Jura) and cies. It reached the lowest value in the fourth coralligenous Tethyan realms for the Late Jurassic time interval (MICHA- level belonging to the succeeding To p a I ubi 0 con- LIK, 1992). structed coralgal facies bearing arborescent coral During the Late Jurassic, Central Dobrogea was situ- colonies (Text-Fig. 5). The high proliferation of arbores- ated in the easternmost part of a vast Mid-European shal- cent corals in the fourth level indicates shallowing up low-water carbonate epicontinental platform lying north through an inshore carbonate depositional area, within of the Tethys and extending longitudinally from Spain, wave base and coming into proximal environment. The through the Paris Basin, Jura and Central Poland, up to more reduced taxonomic variety of the Lower Kimmerid- Central Dobrogea, and further to South Crimea, North gian brachiopod community in the Topalu arbores- Caucasus and Kopet-Dagh (Text-Fig. 6). In terms of Early cent coralgal subfaciesiscorrespondinglycounter- and Middle Jurassic brachiopod provinciality, the Euro- balanced by a notable individual abundance and shell- pean epicontinental seas were the home of the NW-Euro- physical size increasing of some opportunistic species, pean bioprovince. Comparatively, the European Late such as Torquirhynchia speciosa and the varied species of Jura- Jurassic epeiric seas overflowed much larger areas on the lina and Zei/lerina. It reflects much more efficient adaptive northern side of the Tethys, due to a major sea level rise recruitment strategies of these species to the rather un- already initiated by Callovian times (ENAY,1980), which led stable, reefal depositional environment characterized by to a more increased habitat heterogeneity and thereby ac- extremely-reduced water-depth, a higher water-energy counts for a more pronounced overall rise in faunal diver- and luminosity, evolving strong trophic group amensalism sity of brachiopod-bearing benthic communities. At the between corals, brachiopods and other benthic organ- same time, large paleobiogeographic connections and isms for living spaces and food resources. Seemingly, the faunal exchanges were established between the varied successful settlement of the above-mentioned opportun- paleobioprovinces of the Boreal and Tethyan realms, thus istic brachiopods in the coralligenous reefal environment making the exact delimitation of their mutual boundaries was ensured also by the initial high abundance of larvae rather uncertain. from spawning and a shorter duration of the larval phase, The Upper Jurassic fossil assemblages of Central 00- so as to compensate the predation of brachiopod larvae brogea, including a plentiful nekton (ammonites, nauti- by coral polyps. loids, belemnites) and an extremely diversified and abun- dant benthos, are strikingly comparable with the coeval fossil assemblages from the above-quoted European re- gions, thus evincing free shelf sea communications (SI- 6. Paleobiogeographic Analysis MIONESCU,1910 a; PATRULlUS,1964; BARBULESCU,1974). However, when comparing Central Dobrogea with these Undoubtedly, the paleobiogeographic affiliation of the regions, the complete absence of any Boreal faunistic ele- varied Dobrogean Upper Jurassic brachiopod faunas was ments is to be noticed, due to its much more southern po- clearly dependent on the rather diversified paleogeo- sition. Insofar as the ammonoid faunas are concerned, the graphic frame of the Dobrogean areas in the Late Jurassic Central Dobrogean Oxfordian-Lower Kimmeridgian Ca- times. As brachiopods share a high potential for paleobio- simcea Formation records a high variety and abundance geographic studies, owing both to a very short planktonic of large-sized perisphinctids, bearing strong ribs on the larval stage and their sessile benthic life style in adult body chamber, such as Kranaosphinctes, Perisphinctes, Subdis- stage (VÖRÖS,1982, 1984, 1988, 1933; MICHALIK, 1992), cosphinctes for the Middle Oxfordian, or Ortosphinctes and De- apparently there should be no probl~ms in deciphering the cipia tor the Upper Oxfordian, which are characteristic paleobiogeographic relationships of the Dobrogean Up- members in the Sub-Mediterranean bioprovince, as it was per Jurassic brachiopod faunas. outlined by CARIOUet al. (1985). On the other hand, the

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other hand, the occurrence of some 0 p pel i i d a e (Tri- chonellids (Septaliphoria and Torquirhynchia), also with large- marginites, Ochetoceras, Taramelliceras), Asp i doc era tin a e sized shells. Their strong homeomorphy, both in outline (Euaspidoceras, Physodoceras) and Pel t 0 cer a tin a e (Epipel- and size, with some Tithonian brachiopods of the Stram- toceras) and Sutneria testifies large-scale relationships with berk-type shallow-water facies, largely widespread in the the Mediterranean bioprovince. Inner Carpathian areas - to which PETERS(1867) and some It is worth emphasizing the strong similarity of the Cen- subsequent researchers wrongly referred the Dobrogean tral Dobrogean Upper Jurassic brachiopod assemblages Upper Jurassic brachiopod faunas - is given only to the occurring in biogenous facies bearing sponges or corals environmentally-controlled convergency in their external in point of taxonomic composition and biomass features morphology. with the brachiopod faunas which currently are paleoeco- Apart from the ammonoid faunas for which the Mediter- logically restrained to the contemporaneous, comparable ranean influence was already foregoing outlined, it is lack- biofacies commonly developing in the varied areas of the ing or much less evident for the Central Dobrogean ammonoid-related Sub-Mediterranean bioprovince, e.g. Jurassic brachiopod faunas. For instance, no Tethyan- Jura and Central Poland. It is especially the sponge-bear- type pygopids or other Mediterranean brachiopods are ing biofacies which elsewhere in the Sub-Mediterranean occurring in the brachiopod assemblages of the Central epicontinental platform share in common the Lacunosella Dobrogean Lower Kimmeridgian coralligenous facies. The species as main biomass (WIERZBOWSKI,1970). absence or scarceness of the Tethyan elements in the Cen- Furthermore, for the Upper Jurassic coralligenous fa- tral Dobrogean Upper Jurassic brachiopod faunas can be cies from Central Dobrogea, it is worth mentioning the out- accounted for most plausibly by the differing depth re- standing occurrence of some brachiopods which are quirements as a fundamental controlling physical factor in commonly found in South Crimea and North Caucasus, the distributional pattern of the benthic faunas of these thus strengthening extensive paleobiogeographic con- two bioprovinces. nections eastwards for Central Dobrogea, too. It is mainly With regard to the conterminous Dobrogean territories the occurrence of some large-sized terebratulids (Juralina lying northerly of the Peceneaga-Camena Fault, the paleo- spp.) besides both symmetric and asymmetric rhyn- biogeographic affiliation of the Oxfordian-Lower Kim-

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meridgian brachiopod faunas delivered by the Sf ä n t a paleobiogeographic and tectonic problems, as already Fa ci e s of the C ä r je Ia r i For mat ion was plainly simi- stressed by VÖRÖS(1993). lar to that already outlined for the coeval Central Dobro- As noted earlier, the meagre brachiopod fauna of the gean brachiopod faunas. As it results from both the litho- Middle Oxfordian Carabair Limestone from Dunavälu de and biofacies development pattern of the calcareous Jos locality is fairly insufficient to allow paleobiogeo- rocks from the Cärjelari area, the western part of the tec- graphic affiliation to be conveniently ascertained. The tonically-active, Peceneaga-Camena transtensile basin Macin landmass, acting as a major zoogeographic bar- was in close paleogeographic connections with the tec- rier, disconnected the main Jurassic sedimentary basins tonically-stable, Central Dobrogean shallow-water carbo- evolving on the Dobrogean areas, i.e. the Tulcea ensialic nate platform (GRÄDINARU,1988). basin, on the one hand, and the couple of the Central Do- As some tectonicians, such as BURCHFIEL(1980) and brogean shallow-water platform and the Peceneaga- NUR & BEN-AvRAHAM (1982) referred to the Dobrogean Camena transtensile basin, on the other hand, so that blocks in the terms of the exotic terrane tectonics, it is to more or less active faunal communications could have be stressed that nowadays, in spite of the opinions of the been possible only around their easternmost ends by the above-mentioned authors favouring more recent times, intermediary of the Proto-Black Sea basin (Text-Fig. 7). there is compelling evidence which warrants that the Cen- The apparent "Mediterranean-looking" development tral Dobrogean blcok, the so-called "Green Schist Block" pattern of the Carabair Middle Oxfordian highly-scat- of the relevant literature, was already juxtaposed to the tered, oligospecific brachiopod fauna may be related to North Dobrogea terrain during Late Jurassic times along the problem of colonizing a muddy substrate and dispar- the Peceneaga-Camena continental boundary transform ities in food supply in deep-water environments, thus ac- fault (GRÄDINARU,1984). Providing sound arguments for it, counting for the drastic reduction not only in population it is once again proved that the brachiopods represent a size but also in individual physical size. However, the more group which shares high potential for solving a number of abundant and diversified ammonite fauna of the Carabair

Kinematics of Peceneaga-(amena oblique-mobile s tri k e-s lip bel t

1 J3 K1 1 2 3/J ~2 - 't. K /K ~~~ 1C ,~- ,.... \:1! dextral dextral dockwist sinistral strike-slip franstllflsile rotational transpressNe sfrikg-slip IJnd dextral strike-slip transtensile strike-slip - Text-Fig.7. Hypothetical palinspastic sketch-map portraying the inferred plate-tectonic relationships and paleogeography in the north-westward adjoining areas of the Proto-Black Sea during Late Jurassic times (not drawn to scale) and the postuJ~ted kinematics (inset) of the Peceneaga-Camena oblique-mobile strike-slip belt. 1 = Peceneaga-Camena transtensional belt including the westward rhyolitic volcanic chain (a) and the eastward incipiently developing para-oceanic transtensile gash (b); 2 = Central and South Dobrogean sectors of the East Moesian Late Jurassic shallow-water carbonate platform; 3 = Proto-Black Sea oceanic basin; 4 = direction of relative motion of the Moesian Platform; 5 = pwe strike-slip (transcurrent) fault; 6 = extensional strike-Slip (transtensile) fault; 7 = compressional strike-slip (transpressive) fault; 8 = thrust (triangles on the overriding plate); 9 = Main occurrences of the Dobrogean Upper Jurassic brachiopod faunas. Abbreviations: Cj = Carjelari; Ck = Cekirgea; Cs = Casimcea; Di - Dunava\u de Jos; H = Har~ova; S = Sartorman; T = Topalu; V = Visterna; PCF = Peceneaga-Camena Fault; COF = Capidava-Ovidiu Fault; CDB and SDB = Central and South Dobrogean blocks.

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Limestone displays a clear-cut affiliation to the Sub-Me- L = 41.4 (30.7-49.2); W = 27.1 (21.0-31.2); T = 20.8 diterranean bioprovince by the perisphinctid and oppeliid (15.5-25.6) genera (Dichotomosphinctes, Dichotomoceras, Glochiceras, Oche- W/L = 0.64 (0.57-0.65); T/L = 0.50 (0.46-0.57); mW/L = toceras), although the relatively high percentage of phyl- 0.57 (0.50-0.63) loceratids (Holcophylloceras, Sowerbyceras) witnesses a strong Dia g nos is: Shell elongate-oval in ventral profile, with influence of the oceanic biome of Tethys, which is also width about 0.65 of length. Convexity moderate to ac- conveniently explainable, likewise for the brachiopod centuate. Strong and massive umbo. Beak-ridges faunas, as a result of the intervening depth control, rather rounded or lacking. Foramen large, circular, perme- than to a veritable provincialism. sothyrid to epithyrid. Symphytium not exposed. An- Therefore, it may be concluded that the very diversified terior commissure uniplicate to weakly sulciplicate. Dobrogean Upper Jurassic brachiopod faunas are closely Shell folded, with straight plicae of variable length and related to the coeval brachiopod communities which cur- confined to the anterior half of the shell. Large hinge- rently inhabited the areas of the ammonite-related Sub- plates, initially gently concave, may become horizontal; Mediterranean bioprovince. In terms of the European Late well differentiated from inner socket-ridges. Crural pro- Jurassic brachiopod provinciality, the latter is largely over- cesses straight, higher than the crura. Moderately high- lapping in scope on the Sub-Mediterranean (Sub-Tethyan arched transverse band. or Jura) realm of MICHALIK(1992). Des c rip ti 0 n: Biconvex, elongate shell, reaching a max- imum length of 49.2 mm. Maximum width nearly in the middle of the shell or a little posteriorly. PIA ratio of 7. Systematic Paleontology whole shell about 1 or slightly more. Umbo wide, mas- sive, suberect to erect, almost in contact with the brach- (Prepared by A. BÄRBULESCU) ial valve, covering the symphytium. Foramen wide, cir- Phylum: Brachiopoda DUMERIL,1806 cular, weakly to strongly marginate, or labiate for about Class: Articulata HUXLEY,1869 20 % of specimens. Lateral commissure oblique to Order: Terebratulida WAAGEN, 1868 arched. Anterior commissure uniplicate to slightly sul- ciplicate, with a narrow or rounded median sinus. The Suborder: Terebratulidina WAAGEN,1868 two lateral plicae not reaching halfway length of the Superfamily: Terebratulacea GRAY, 1840 dorsal valve. Ventral valve strongly convex in the middle Family: Terebratulidae GRAY,1840 of the posterior half. Maximum convexity of the whole Genus: Dorsoplicathyris shell approximately halfway the length. All the speci- ALMERAS,1971 mens available are adult or gerontic. Folding of the shell and biplication of the anterior commissure appear not to Ty pes pee i es: Terebratula dorsoplicata SUEss-DESLONG- develop until the shell is at least 25-30 mm in length. CHAMPS,1886. Rem ark s: The external characters are sufficiently dis- tinctive to justify recognition of a new species. Dorso- plicathyris petersi n.sp. is differing from other large-sized Dorsoplicathyris petersi n.sp. Oxfordian species of Oorsoplicathyris, such as O. farcinata (PI. 3, Figs. 5-8; Text-Figs. 8-11) (DOUVILLE,1886), O. prolifera BOULLlER,1976 and O. subin- Hol 0 typ e: LPB.III.B.0124 *) - PI. 3, Figs. 7 a-c. signis (ETALLON,1862), in being relatively narrower and Dimensions of holotype: (in mm) thicker, more oval, less triangular posteriorly or sub- L = 46.6; W = 27.8; T = 26.3 pentagonal. The new species described here is ap- proaching the oval morphe of O. richei BOULLlER,1976, Stratum typicum and locus typicus: Uppersec- but differs from it in being much larger-sized and more tionofthe Cekirgea stromatolitic algal series, convex, also in having a more pronounced oval outline. Upper Oxfordian (Bimammatum and Planula Zones), Veriga Arm (Danube) cliff, north of Topalu, Central Dobrogea. Occ u rrence: Veriga Arm (Danube) cliff, north ofTopalu, from C e kir g e aSt rom at 0 lit i c A Ig a I S er i es, Derivatio nominis: Species named in honour of the where O. petersi n.sp. was collected from the well-bedded Austrian geologist K.F. PETERS. limestones intercalated between the first and second Mat e ria I: 30 well-preserved specimens, as follows: LPB.III.B.0123 to 0125 (3 specimens), 0267 (20 spec- imens), 0268 to 0269 (2 specimens, serially-sectioned) Text-Fig.8 .... (p. 70) from Cekirgea Stromatolitic Algal Series, Up- Serial transverse sections through Dorsoplicathyris petersi n. sp., LPB. III. B.0268. per Oxfordian, Veriga Arm (Danube) cliff, north ofTopalu; The cardinal process is seen at 2.3; the initially concave shape of the 0258 (2 specimens) from Cekirgea Stromatolitic hinge-plates is shown at 8.0-8.1; the horizontal shape of hinge-plates is A Ig a I Se r i es, Upper Oxfordian, "La Vii" hill, north of well shown at 9-11.2; note the height of the crural bases at 10.2-11.6; Här~ova; 0259 (3 specimens) from Vis t ern aBi 0 con- the maximum development of the crural process with the carenate base is seen at 12.4-12.9, and the height of the transverse band above the structed Spongalgal Series, Upper Oxfordian, floor of the dorsal valve at 16.0-16.5. Visterna valley. Numbers under serial sections indicate the distance in mm from the pos- Dim ens ion s: (in mm) - median value and range of terior end of the shell; Lp = originallength of the pedicle valve; the bar shows the scale of serial sections. variation:

*) Abbreviations: Text-Fig. 9 ...... (p. 71) LPB.III.B. - Collection of the Laboratory of Paleontology, Bucharest Serial transverse sections through Dorsoplicathyris peters; n. sp., LPB. III. University, Catalogue Romania - Brachiopoda; L = length of shell; B.0269. W = width of shell; T = thickness of shell; W/L = width/length ratio; The pedicle-collar is seen at 0.6-1.3; the long horizontal hinge-plates are to be seen at 6.1-6.5; the distinct inner socket-ridge at 6-6.5; the trans- T/L = thickness/length ratio; mW/L = maximum width/length ratio; verse band with plate-apex is shown at 12.6-12.8. PIA = posterior/anterior ratio.

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L p:: 51. 6 m m 9 I I I I 1mm ~J~~ 1.3 4.3 6.3 6.9

7.2 7.4. 7.5 7.6 7.6

7.9 6.0 8.1 6.4.

~~~~~~ ...... - ..... "" ... --,---' ------9.0 10.2 11.2

j J h \ ! ,.- ~. ~ ... " ~~ - - - ~ ...... - .. - - - - ,------.... ---- ... - - ... ----- 11. 6 12.1 12.4. 12.9 I \ I \ \ ) i I ...... - ..... ~~ ...... - -~ ..~ -- ~~ - - ... - - .... - ...... ------13.3 - 16.5 \ 15.1 16.0 \ '- \ / '- ,/

". ~ .... -... ,~ -" -- .. -- ...... *" .. - .... -- ..... ------' ------"'-"'---" 16.8 17.5 17.9 18.3 Text-Fig.8. Explanation see p. 69.

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o 5mm I I @ 0.2 0.6 4.6 4.8

6.5

j

7.5 7.8 8.2

, ( ) { ) ( \ ~ ~ ) ~ --- ~..:::::::- ~ -=--- ~~~ ~ 9.1 9.7 10.3 11.2 11.7

n I ) , f\ I \ \ J \. ~\... ./ -

~ 14.1 14.4

Text-Fig.9. Explanation see p. 69.

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Mat e ria I: 35 well-preserved specimens, as follows: W,T mm LPB.III.B.0121 (24 specimens); 0274 (1 specimen, serially-sectioned) from Ce k i rg e aSt ro mat 0 lit i c 32 A Ig a I Se r i es, Middle-Upper Oxfordian, Cekirgea val- ley; 0270 (2 specimens) from Cekirgea Stromato- 30 lit i c A Ig a I Se r i es, Upper Oxfordian, Veriga Arm (Danube) cliff, north of Topalu; 0271 (4 specimens) from 28 Cekirgea Stromatolitic Algal Series, Upper Oxfordian, Atärnati, south of Ghindäre~ti; 0272 (1 spe- 26 cimen) from Cekirgea Stromatolitic Algal Se r i es, Upper Oxfordian, "La Vii" hill, north of 24 Här~ova; 0273 (3 specimens) from Cekirgea Stro- matolitic Algal Series, Upper Oxfordian, Visterna 22 valley. Dim ens ion s: (in mm) - median value and range of 20 variation: L = 34.4 (25.6-43.0); W = 26.5 (20.2-31.5); T = 20.3 18 (14.6-25.5) W/L = 0.76 (0.68-0.90); T/L = 0.60 (0.47-0.80); mW/L = 16 0.61 (0.54-0.67) Lmm Des c rip ti 0 n: Shell pentagonal in ventral profile; une- 14 qually biconvex. Brachial valve flattened, pedicle valve 30 32 34 36 38 40 42 44 46 48 much more convex. Umbo strongly incurved, in contact with the brachial valve. Symphytium hidden. Foramen Text-Fig. 10. elongate, oval, labiate, tends to be narrower fantiform Scatter-diagram showing the relationships of width (W) to length (L) and thickness (T) to length (L) in Dorsoplicathyrispetersin. sp., based on mea- for gerontic specimens. Beak-ridges rounded. Lateral surements of 27 specimens. commissure strongly arched, in anterior half inclining ventralwards at about 100°. Anterior commissure recti- coralligenous levels, also from the marginal parts of the marginate to quadrate-uniplicate or episulcate- coralligenous buildups of the second level; "La Vii" hill, parasulcate. Shell folding is represented by two short, north of Här~ova, from Cekirgea Stromatolitic lateral plicae separating a large median depression, re- Algal Series; Visterna valley, from Vi sterna Bio- latively deep at the largest-sized specimens. Hinge- constructed Spongalgal Series; Upper Oxfor- plates subhorizontal or horizontal, thin and long, with dian (Bimammatum and Planula Zones) for all occurrences. long crural bases, initially dorsally-attached, later both dorsally and ventrally; the free crurae extending dor- salwards; the crural processes long and thin, slightly W/L T/L N curved. Moderately-arched transverse band. Rem ark s: Studying the Upper Jurassic brachiopods from Central Dobrogea, SIMIONESCU(1910 b) described 16 the new species Terebratula carsiensis. The name of the species was derived from the Latin name, Carsium, of 12 the present town Här~ova. The material available for cre- ating the new species has been represented by two specimens, from which only one complete. No informa- 8 tion was given in the original description regarding the internal structure. Later, KYANSEP(1961) interpreted the Crimean specimens referred by him to SIMIONESCU'S 4 species as belonging to the genus Neumayrithyris TOKUY- AMA,1956. Our investigations on the internal structure of o specimens recovered from the stratotype of Terebratula 0.56 0.64 0.72 0.78 0.41. 0.52 0.60 carsiensis SIMIONESCU,1910 pointed to the presence of a distinctive character materialized by the pendant as- Text-Fig.11. Histograms showing the frequency of W/L and T/L ratios in Dorsoplica- pect of crural bases, projecting towards the brachial val- thyris petersi n. sp.; N = number of measured specimens. ve (Text-Fig. 12). They are initially dorsally-attached and later both dorsally and ventrally. This character was de- cisive when WESTPHAL(1970) described the new genus Genus: Placothyris WESTPHAL, 1970 Placothyris. BOULLIER(1976) also identified this internal character to the specimens from Jura and Poitou. Ty pes pee i es: Placothyris rollieri HAAS, 1893 pars Therefore, by its internal structure SIMIONESCU'STere- bratula carsiensis must be assigned to the genus Pta- cothyris. Placolhyris carsiensis (SIMIONESCU, 1910) Moreover, the external characters of the genus (PI. 3, Figs. 1-3; Text-Figs. 12-14) Neumayri- thyris are differing from those of Placothyris. The former 1910 Terebratulacarsiensis SIMIONESCU, p. 401, PI. V, Figs. 3-4. non 1961 Neumayrithyris carsiensis (SIMIONESCU); KYANSEP, p. 78, has a much less convex shell, more sinuous lateral com- PI. VI, Figs. 1 a-c, Text-Fig. 32. missure and incipient sulciplicate anterior com- 1976 Ptacolhyris sp. BOULLlER, PI. XI, Figs. 6 a-c. missure.

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Text-Fig. 12. Serial transverse sections lp = 32.6 mm through Placolhyr/s cars/ens/s o. (SIMIONESCU). LPB.III.B.0274. The pedicle collar is shown at 1.8-2.3; the horizontal, fine hinge-plates and the crural bases, only dorsal- ly-attached, are seen at 6.1-6.4; both those dorsally- and ventrally-attached, ap- 0.6 1.4 1.5 1.8 pear at 7.0-7.5; the free cru- 2.3 ra extending dorsalwards as thin long curve is seen at 4.0 7.7-8.3; the maximum de- velopment of crural process at 10.0-10.6, and the mode- rately low-arched transverse band at 12.9-13.1. , ,;/~@;,~,;/ ,;/~/~/v"_-.., 6 .3 6. 4 7.0 7.3 ~\illfw\ßI 7.5 7.1 8.1 8.3 ~~&~ 8;7 9.1 10.0 10.6 ~00~ 10. 12.0 12.4 12.8

12.9 13 .1 13.4 13.5

Placathyris carsiensis is differing from P rallieri (HAAS, 1893), Bioconstructed Spongalgal Series, Middle the type species of the genus, and, respectively, from P Oxfordian, Casimcea Syncline. welshi BOULLlER,1976 in being markedly larger-sized and thicker, with strongly incurved umbo and much more ar- ACknowledgements ched lateral commissure. This paper was presented at the Regional Field Symposium on Meso- o c cur ren ce: Placathyris carsiensis is frequently occurring zoic Brachiopods, held in Vörösbereny, Hungary, 6.-11. September, in the Cekirgea Stromatolitic Algal Series, 1992. The authors gratefully acknowledge the organizers' financial assi- stance which facilitated their attendance to the symposium. We are parti- Middle to Upper Oxfordian (Transversarium and Bimammatum cularly grateful to Dr. ATTILA VÖRÖS(Budapest), who also critically revie- Zones), Cekirgea valley and Veriga Arm (Danube) cliff, wed the manuscript and made valuable suggestions for its improvement. north of Topalu. It is sparsely occurring in the Vis t ern a Special

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W,T mm W/L T/L N 32 16 30 12 28 8 26 24 4 22 0 0.65 0.75 0.85 0.45 0:55 0.65 0.75 20 Text-Fig.14. Histograms showing the frequency of W/L and TlL ratios in Placothyris 18 carsiensis (SIMIONESCU);N = number of measured specimens. 16 mm 14 25 27 29 31 33 35 37 39 41 43 thanks are given to Mrs. SORANAGEORGESCU-GORJANlor her help in im- Text-Fig. 13. proving the English text. Scatter-diagram showing the relationships of width (W) to length (L) and Finally, warm thanks are expressed to Dr. ALBERTDAURER,the Editor 01 thickness (T) to length (L) in (SIMIONESCU),based on Ptacothyris carsiensis Jahrbuch der Geologischen Bundesanstalt, for the opportunity to pu- measurements of 38 specimens. blish this paper in the present volume.

North Dobrogea Juralina cf. subformosa (ROLLIER). Figs. 20a-b: Carabair Limestone LPB. III. B. 0105 - Call. GRÄDINARU. Upper Oxfordian-Lower Kimmeridgian, Vararia quarry. Montic/arella czenstochowiensis (ROEMER). Figs. 1a; 2 a-b: x 3, LPB. III. B. 0098 - Call. GRÄDINARU. Middle Oxfordian, Carabair hill. Central Dobrogea Lacunosella sparsicosta (QUENSTEDT). Figs. 3a-b; 4a,d; 5 a: Casimcea Formation LPB. III. B. 0099 - Call. GRÄDINARU. Middle Oxfordian, Carabair hill. Visterna Bioconstructed Spongalgal Series Cärjelari Formation - Sfänta Facies Lacunosella trilobataeformis WISNIEWSKA. Figs. 17a,c; 19a-c: Torquirhynchia astieriformis CHILDS. LPB.III. B. 0106 - Call. BÄRBULESCU. Figs. 6a-c; 7a-c; 8a,c; 9a; 10 a: Middle Oxfordian, Casimcea valley. LPB. III. B. 0100 - Call. GRÄDINARU. Figs. 18a: Upper Oxfordian-Lower Kimmeridgian, Vararia quarry. LPB. III. B. 0107 - Call. DRÄGÄNESCU. Moeschia sp. Middle Oxfordian, Särtorman valley. Figs. 11 a-c: Argovithyris stockari (MOESCH). LPB. III. B. 0101 - Call. GRÄDINARU. Figs. 21 a-c; 23a: Upper Oxfordian-Lower Kimmeridgian, Vararia quarry. LPB. III. B. 0108 - Call. BÄRBULESCU. Moeschia granu/ata BOULLIER. Middle Oxfordian, Casimcea valley. Figs. 12a; 13a-c; 14 a-b: Figs. 24a,c: LPB. III. B. 0102 - Call. GRÄDINARU. LPB. III. B. 0109 - Call. DRÄGÄNESCU. Upper Oxfordian-Lower Kimmeridgian, Väraria quarry. Middle Oxfordian, Casimcea valley. Zeillerina sp. Nuc/eata nuc/eata (SCHLOTHEIM). Figs. 15a-c: Figs. 22a-c: LPB. III. B. 0103 - Call. GRÄDINARU. LPB. III. B. 0110 - Call. BÄRBULESCU. Upper Oxfordian-Lower Kimmeridgian, Vararia quarry. Middle Oxfordian, Casimcea valley. Figs. 16a-c: LPB. III. B. 0104 - Call. GRÄDINARU. Oxfordian-Lower Kimmeridgian, Sfänta hill-northern slope. All figures natural size unless indicated otherwise.

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Central Dobrogea Casimcea Formation

Cekirgea Stromatolitic Algal Series

Montic/arella slrioplicala (QUENSTEDT). Figs. 1a-d: x 2.5, LPB. III. B. 0111 - Call. BARBULESCU. Middle Oxfordian, Cekirgea valley. Seplaliphoria pinguis (ROEMER). Figs. 2 a-c: LPB. III. B. 0112 - Call. BARBULESCU. Upper Oxfordian, Veriga Arm (Danube) cliff, north of Topalu. Lacunosella sparsicosla (QUENSTEDT). Figs. 3 a, c-d; 5 a-d: LPB. III. B. 0113 - Call. BARBULESCU. Middle Oxfordian, Baroi hill, north of Här~ova. Figs. 4 a, d: LPB. III. B. 0114 - Call. BARBULESCU. Middle Oxfordian, "La Vii" hill, north of Här~ova. Acanlhorhynchia spinu/osa (OPPEL). Figs. 6 a-b: LPB. III. B. 0115 - Call. BARBULESCU. Figs. 18 a, c: x 1.8, LPB. III. B. 0115 - Call. BARBULESCU. All figures - Middle-Upper Oxfordian, Cekirgea valley. Lacunosella cracoviensis (QUENSTEDT). Figs. 7 a-c; 8 a; 9 a-c: LPB. III. B. 0116 - Call. BARBULESCU. Figs. 10 a; 11 a-c; 14 a-c: LPB. III. B. 0116 - Call. BARBULESCU. All figures - Middle-Upper Oxfordian, Cekirgea valley. Torquirhynchia speciosa (MÜNSTER). Figs. 12 a; 13 a-c: LPB. III. B. 0117 - Call. BARBULESCU. Upper Oxfordian, Veriga Arm (Danube) cliff, north of Topalu. Moeschia a/ala (ROllET). Figs. 15 a-c; 16 a: LPB. III. B. 0118 - Call. BARBULESCU. Middle Oxfordian, Cekirgea valley. Moeschia granu/ala BOUllIER. Figs. 17 a-b: LPB. III. B. 0119 - Call. BARBULESCU. Uppermost Oxfordian, Cekirgea valley. Oiclyolhyris kurri (OPPEL). Figs. 19 a-c: LPB. III. B. 0120 - Call. BARBULESCU. Middle Oxfordian, Cekirgea valley.

All figures natural size unless otherwise indicated.

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Central Dobrogea Casimcea Formation

Cekirgea Stromatolitic Algal Series Placothyris carsiensis (SIMIONESCU). Figs. 1a-c; 2a-c; 3a-c: LPB. III. B. 0121 - Call. BARBULESCU. Middle Oxfordian, Cekirgea valley. Oorsoplicathyris farcinata (DOUVILLE). Figs. 4 a-c: LP8. III. 8. 0122 - Call. 8ARBULESCU. Middle Oxfordian, Cekirgea valley. Oorsoplicathyris petersi n. sp. Figs. 5 a-c: Paratype, LPB. III. B. 0123 - Call. BARBULESCU. The smallest specimen. Figs. 6 a-c; 8 a-c: Paratypes, LPB. III. B. 0125 - Call. BARBULESCU. Figs. 7 a-c: Holotype, LPB.III. B. 0124-Coll. BARBULESCU. All figures - Uppermost Oxfordian, Veriga Arm (Danube) cliff, north of Topalu. Juralina subformosa (ROLLI ER). Figs. 9 a-c: LPB. III. B. 0251 - Call. BARBULESCU. Uppermost Oxfordian, "La Vii" hill, north of Här~ova. Zeillerina delemontana (OPPEL). Figs. 10 a: LPB. III. B. 0252 - Call. BARBULESCU. Upper Oxfordian, Veriga Arm (Danube) cliff, north of Topalu. Figs. 13 a-b; 14 a-c: LPB. III. B. 0253 - Call. BARBULESCU. Middle Oxfordian, Cekirgea valley. Oictyothyris kurri (OPPEL). Figs. 12 a-c: LPB. III. 0254 -Call. BARBULESCU. Middle Oxfordian, Cekirgea valley.

Topalu Bioconstructed Coralgal Series Cheirothyris f1eurieusa (D'ORBIGNY). Figs. 11 d; 16 a-c: LPB. III. B. 0255 - Call. BARBULESCU. Lower Kimmeridgian, Veriga Arm (Danube) cliff, north of Topalu. Zeillerina delemontana (OPPEL). Figs. 15 a, c: LPB. III. B. 0256 - Call. BARBULESCU. Lower Kimmeridgian, Veriga Arm (Danube) cliff, north of Topalu.

All figures natural size.

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Central Dobrogea Casimcea Formation

Topalu Bioconstructed Coralgal Series Septaliphoria moravica (UHLIG). Figs. 1a-c: LPB. III. B. 0257 - Call. BAuLESCU. Specimen with large arcuate anterior commissure. Figs. 2 a-c: LPB. III. B. 0258 - Call. BAuLESCU. Specimen with uniplicate anterior commissure, and quadrate median fold. Figs. 3 a-c: LPB. III. B. 0259 - Call. BAuLESCU. The largest specimen. All figures - Lower Kimmeridgian, Veriga Arm (Danube) cliff, north of Topalu. Juralina bullingdonensis (ROLLIER). Figs. 4 a-c: LPB. III. B. 0260 - Call. BAuLESCU. Lower Kimmeridgian, Tataru valley, Topalu. Juralina topa/ensis (SIMIONESCU). Figs. 5 a-c: LPB. III. B. 0261 - Call. BAuLESCU. Lower Kimmeridgian, Tätaru valley, Topalu. Juralina sp. Fig. 6a: LPB. III. B. 0262 - Call. BAuLESCU. Lower Kimmeridgian, Tätaru valley, Topalu. Juralina kokkoziensis (MOISEEV). Figs. 7 a-b: LPB. III. B. 0263 - Call. BAuLESCU. Lower Kimmeridgian, Tätaru valley, Topalu. Juralina castel/ensis (DOUVILLE). Figs. 8 a, d: LPB. III. B. 0264 - Call. BAuLESCU. Lower Kimmeridgian, Veriga Arm (Danube) cliff, north of Topalu. Digonel/a sp. Figs. 9 a-c: LPB. III. B. 0265 - Call. BAuLESCU. Lower Kimmeridgian, Veriga Arm (Danube) cliff, north of Topalu. Au/acothyris sp. Figs. 10 a-c: LPB. III. B. 0266 - Call. BAuLESCU. Lower Kimmeridgian, Veriga Arm (Danube) cliff, north of Topalu.

All figures natural size.

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References

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