Upper Oligocene (Chattian) brachiopod fauna from the Aquitaine Basin, southwestern France and its paleoenvironmental implications

ABSTRACT Brachiopods from the Upper Oligocene (Chattian), Aquitaine Basin, southwestern France comprise nine species in seven genera: Novocrania Lee & Brunton, 2001, Terebratulina d'Orbigny, 1847, Megathiris d'Orbigny, 1847, Argyrotheca Dall, 1900, Joania Álvarez, Brunton & Long, 2008, Megerlia King, 1850, and Lacazella Munier-Chalmas, 1880. One megathyridid is described as a new species, Joania peyrerensis n. sp., characterized by ornamentation of 6–8 distinct, sharp ribs and by triangular, plate-like teeth. With the exception of Megathiris detruncata (Gmelin, 1791) and Lacazella mediterranea (Risso, 1826), all species are recorded for the first time from the Oligocene of the Aquitaine Basin. In taxonomic composition this brachiopod fauna displays close affinity with the Miocene faunas of the Mediterranean Province and Central Paratethys. The dominance of micromorphic megathyridids and thecideides in the Peyrère assemblage, characteristic of cryptic habitats suggests the presence of submarine caves and/or crevices, thus supporting the previous interpretations of this faunistic assemblage as a cave biocenosis. Frequency of gastropod drillings observed on the investigated brachiopods is low (4%) as is in most Cenozoic brachiopod populations. The paleotemperatures calculated from the &dgr;18O values of brachiopod shells (21 to 24°C) correspond well to a paleoenvironmental interpretation based on paleoecology of other taxonomic groups.


INTRODUCTION
Although brachiopods have lost importance in the Cenozoic and their taxonomic diversity is low, they are a stable, locally even dominant, element of the benthic fauna in European Tertiary deposits. Eocene brachiopods are well known and described from the whole of Europe, and although their taxonomic composition in particular assemblages can differ significantly, many species have a very wide geographical distribution from Great Britain to Ukraine. Miocene brachiopods are also well known in the whole of Europe, being especially studied from the Paratethyan and Mediterranean provinces, and they are predominantly micromorphic forms.
It is worth mentioning that the brachiopod assemblage from northern Germany described as Lower Oligocene by von Koenen (1894) has been found to be Upper Eocene in age (see De Geyter et al. 2006). e present paper deals with a rich Upper Oligocene (Chattian) brachiopod fauna from the Aquitaine Basin (SW France) that belongs to the Atlantic Province. Brachiopods, in majority excellently preserved, with more than 1400 specimens are represented by nine species belonging to seven genera. Although so rich, this fauna has never been fully described before, however, the presence of the genera Megathiris, Argyrotheca and Lacazella was mentioned by several researchers (Peyrot 1932;Pajaud 1974;Lozouet 2004). Interestingly, brachiopods were described from the Aquitaine Basin from the younger, Miocene, deposits where inarticulate Lingula and Discradisca Stenzel, 1964, and micromorphic rhynchonellide Cryptopora Jeffreys, 1869 were recognized (Bitner & Cahuzac 2004Emig et al. 2007). Bitner M. A. et al.

GEOLOGICAL SETTING
Marine Upper Oligocene deposits crop out only in the south-western part of the Aquitaine Basin ( Fig. 1; Cahuzac et al. 1995;Lozouet 2004). ey are of transgressive character, having been deposited after a major regression related to the global sea-level fall at the Lower-Upper Oligocene boundary (Vail et al. 1977;Dolin et al. 1985). On the basis of the calcareous nannoplankton these deposits are referred to the zones NP24 and NP25 that correspond with the Chattian (Cahuzac et al. 1995). Moreover, based on neritic larger foraminifera abundant in these levels, they are attributed to the SBZ 23 biozone (Shallow Benthic Zone) of Cahuzac & Poignant (1997). ey contain a rich benthic fauna, composed chiefly of gastropods, bivalves, corals, serpulids, bryozoans, and brachiopods, and are interpreted as having been deposited under tropical/subtropical conditions (Lozouet 2004).
Brachiopods were found at several localities ( Fig. 1) in the Chattian deposits represented by various facies (Cahuzac et al. 1995;Lozouet 2004). In the north, in the vicinity of Dax (Bezoye, Estoti, Abesse) shallow-water calcareous facies with coral reefs occur. At Escornebéou the Upper Oligocene is represented by sandy marls and calcareous sands. e localities of Peyrère, Bélus and St-Étienned'Orthe are situated in the area that is considered to be originally a submarine canyon (Kieken 1973). e incision of the paleocanyon which is several hundred meters deep, may be related to the significant drop of sea-level (Dolin et al. 1985;Lozouet 2004). At the head of the paleocanyon (Peyrère, Bélus) the infralittoral to circalittoral facies with dominance of marls occur. To the west the facies become deeper-water and are represented by circalittoral to epibathyal marls and muddy sands at St-Étienne-d'Orthe. MATERIAL AND METHODS e investigated brachiopods come from seven outcrops, namely Peyrère, Bélus, St-Étienne-d'Orthe, Escornebéou, Bezoye, Estoti and Abesse, in the Aquitaine Basin, SW France (Fig. 1). e material comprises mostly specimens obtained from the bulk samples washed and wet-sieved. e larger fraction was sorted in the field, while finer fractions were picked manually under the binocular microscope at the laboratory.
ere are also some specimens from the collections of the University of Bordeaux-1. Total number of specimens is 1466 (697 articulated specimens and 769 separate valves).
For isotope analysis, samples were taken by microdrilling from the inner surface of shells. e analyses were done using a Finnigan MAT Delta Plus gas isotope mass spectrometer at the Light Isotope Laboratory of the Institute of Geological Sciences, Polish Academy of Sciences, Warsaw. e carbonate powder was reacted with 100% orthophosphoric acid under vacuum at 70°C in the KIEL IV carbonate device, which was coupled online to a Finnigan MAT Delta Plus gas isotope mass spectrometer. Isotope values are reported as parts per mil in the usual δ-notation relative to the PDB standard (defined via NBS 19). e spectrometer external error amounts to less than ± 0.08. We took 20 samples from 20 specimens of two most common species, Megathiris detruncata and Lacazella mediterranea. Additionally two samples were also taken from the third commonest species, Terebratulina retusa. e isotopic paleotemperatures were calculated from the δ 18 O values using the equation: where δ c means the δ 18 O values of brachiopod samples relative to the PDB standard and δ w means the δ 18 O values of seawater relative to the SMOW standard (see Nehyba et al. 2008).
The SEM micrographs were taken in the SEM laboratory of the Institute of Paleobiolo-gy (Warszawa) using a Philips XL-20 scanning microscope. e investigated material is deposited in the paleontological collection in the Muséum national d'Histoire naturelle, Paris (MNHN.F, Lozouet coll.), and in the University of Bordeaux-1 (nos 1498 and 1499 of the Peyrot Collection; Nolf-Cahuzac Collection; Larralde Collection; Buisson Collection).

REMARKS
Novocrania anomala is rare (12 specimens) in the studied material, found only in two localities. e material is poorly preserved, both outer and inner surfaces are usually worn but it corresponds well with that hitherto described (Logan 1979(Logan , 1998Logan & Long 2001;Álvarez & Emig 2005). e shell is small with maximum length 15.6 mm, subcircular in outline, wider than long. e posterior adductor muscle scars are large, subcircular, situated near posterior margin in both valves. e anterior adductor muscle scars are oval, elevated. On some specimens mantle canals can be observed (Fig. 2C Anomia retusa Linnaeus, 1758: 701, no. 191.

REMARKS
is species has been found in three localities but only in one, Peyrère, it is numerous. e investigated specimens, although often crushed and/ or damaged, are consistent with those hitherto described having, however, smaller size (Logan 1979; Taddei Ruggiero 1985;Gaetani & Saccà 1985;Álvarez & Emig 2005). e shell is ovate to subpentagonal, biconvex, covered with numerous, fine ribs that are coarser and strongly beaded in young individuals (Fig. 2E). e cardinalia are typical for the genus with prominent inner socket ridges and deep dental sockets. e loop is preserved only in a young specimen, with crural processes not yet united (Fig. 2F Dall (1920) showed that the first binominal valid name given to this species was Anomia detruncata Gmelin, 1791, and this should therefore be used for the type species (see also omson 1927: 213). (Gmelin,

REMARKS
Megathiris detruncata is one of the most common species (more than 400 specimens) in the investigated assemblage, found in five localities. It was already recorded from the studied area (Peyrot 1932;Lozouet 2004). e specimens from the Aquitaine Basin correspond well to those hitherto described (e.g., Logan 1979; Taddei Ruggiero 1985;Bitner 1990;Bitner & Schneider 2009). e shell is small (our largest specimen is a dorsal valve 7.0 long and 8.1 mm wide), transversely ovate in outline, covered with few wide, rounded ribs. e

REMARKS
Argyrotheca cuneata is rare in the studied assemblage and was found in only one locality. e shell is small, rectangular with greatest width usually at hinge line. e shell surface is covered with 6-8 single, low and rounded ribs. e foramen is large, triangular with a wide pedicle collar supported by a septum. e teeth are widely separated lying parallel to the hinge line. e dorsal median septum is high, triangular in profile with 3-4 serrations.
Argyrotheca cuneata can be distinguished from a second Argyrotheca species, A. bitnerae Dulai, 2011 and Joania cordata (Risso, 1826) in rectangular outline and ribbed surface. Additionally, A. cuneata differs from J. cordata in lacking tubercles on the inner margin. e absence of margin tubercles distinguishes it also from Joania peyrerensis n. sp.
In shell outline and ornamentation A. cuneata resembles Megathiris detruncata, being, however, easily distinguishable internally from the latter species; M. detruncata has three septa on the dorsal valve.     Dorsal valve interior with well developed, narrow inner socket ridges. Dental sockets deep. Cardinal process as small depression. Crura very short, as are crural processes (see Fig. 5F-I). Descending branches fuse with valve floor (Fig. 5F, H), and emerge to attach to median septum. Median septum high, triangular in profile, without serrations (Fig. 5I, K).

REMARKS
is species is relatively common in the studied material being found in four localities. e investigated specimens correspond well, both externally and internally, to those described as Argyrotheca bitnerae by Dulai in Dulai & Stachacz (2011) from the Middle Miocene of Poland. e Oligocene specimens differ from the Miocene ones in being slightly larger and having the septum without serrations. Dulai in Dulai & Stachacz (2011) observed 2-3 weak serrations at the anterior slope of the septum.
is brachiopod was earlier attributed to the species A. cistellula (Searles-Wood, 1841) by Barczyk & Popiel-Barczyk (1977) and Popiel- Barczyk & Barczyk (1990). However, A. cistellula has a shell transversely subrectangular in outline, with a wide straight hinge line (Logan 1979). In addition, the pedicle collar in A. cistellula is excavated anteriorly, while in A. bitnerae the pedicle collar is close to the valve floor.
In shell shape, smooth surface, sessile pedicle collar and short crura with blunt crural processes A. bitnerae bears a close resemblance to the Early Miocene species A. kupei Hiller, Robinson & Lee, 2008 from New Zealand, differing, however, in having smooth slope of the dorsal septum (Hiller et al. 2008;Hiller 2011). In A. kupei the anterior slope of septum has 2-3 knob-like extensions.
Externally, in smooth surface and triangular outline with a short hinge margin, the studied specimens resemble Joania cordata but they differ strongly from the latter species internally. Joania cordata possesses a prominent cardinal process and marginal tubercles on inner surface of both valves (Logan 1979;Álvarez et al. 2008    province, living today in the north-eastern North Atlantic and the Mediterranean Sea (Logan 1979(Logan , 1983(Logan , 1988 at the depth of 3 to 600 m (Logan 2007). et al. (2008) for those Argyrotheca species that have a narrow hinge line, prominent cardinal process and tubercles on the inner margin. e specimens from the Aquitaine Basin agree well with those described from the Miocene of the Central Paratethys (Bitner 1990(Bitner , 1993Bitner & Pisera 2000;Bitner & Kaim 2004), differing from the Recent ones described and illustrated by Logan (1979) in having a lower median septum. e shell is small, smooth or covered with poorly defined, shallow ribs. e large foramen is triangular with a wide pedicle collar supported by a low median septum. e inner socket ridges are narrow but high, and the cardinal process is prominent. e specimens bear tubercles on the inner margin of both valves.

DESCRIPTION
Shell small, not exceeding 3 mm in length, rounded subrectangular in outline with maximum width at mid-valve, weakly biconvex. Shell surface covered with 6 to 8 distinct ribs. Hinge line shorter than maximum width, slightly curved. Anterior commissure rectimarginate. Beak high with distinct beak ridges. Interarea narrow. Foramen large, triangular, hypothyrid flanked by elevated, narrow deltidial plates. Ventral valve interior with plate-like, triangular teeth ( Fig. 7F-H). Pedicle collar wide, excavate anteriorly, supported by a slender septum that extends beyond mid-valve. On inner surface radial ridges terminating in tubercles (Fig. 7I).
Dorsal valve interior with narrow but high inner socket ridges. Dental sockets deep. Cardinal process distinct. Septum high, triangular in profile, with 4 serrations. Numerous tubercles on inner margin (Fig. 7D, E). Loop not preserved. et al. (2008) created Joania as a monospecific genus, however, since that time several Argyrotheca species have been transferred into the genus Joania, based mostly on the important diagnostic character -numerous radial ridges terminating anteriorly in tubercles on the inner margin. e presence of marginal tubercles in the specimens from the Aquitaine Basin supports their attribution to the genus Joania.

Álvarez
In the ornamentation of 6-8 distinct, sharp ribs J. peyrerensis n. sp. can be easily distinguished from other so far described Joania species. e shell surface of J. cordata is smooth or covered with almost imperceptible costae (Logan 1979;Bitner 1990;Álvarez et al. 2008). In addition, both species differ in the nature of the teeth; in J. peyrerensis n. sp. the teeth form a triangular plate, while in J. cordata they are hooked. e shell of a Recent Indo-Pacific species J. arguta (Grant, 1983) is also completely smooth without any costae (Bitner 2008;Simon 2010). e teeth in this species are, similarly like in J. cordata, hooked given off dorsally, thus differing clearly from J. peyrerensis n. sp. e studied specimens differ strongly from the Lower Pleistocene species from southern Italy,  Joania ageriana, originally described as Argyrotheca ageriana by Taddei Ruggiero (1993). Joania ageriana is much larger, reaching 7 mm in length, and ornamented by 14 to 18 rounded ribs (Taddei Ruggiero 1993, 1994 Dulai (2010a)

REMARKS
Megerlia truncata is very rare in the investigated assemblage, found only in one locality. e material is poorly preserved, all specimens are crushed, preventing examination of internal structure. However, the size and characteristic ribbed ornamentation support attribution to this species. is is the first record of this species from the Oligocene but the genus Megerlia was already reported from the Oligocene of Hungary (Dulai 2010b).

REMARKS
is species dominates in the studied assemblage and is represented by more than 800 specimens. Its presence was already reported from the Oligocene of the Aquitaine Basin (Peyrot 1932;Pajaud 1974;Lozouet 2004).
Although consistent with the hitherto described specimens (see Pajaud 1970;Logan 1979;Álvarez & Emig 2005) the specimens from southern France are much larger, reaching about 10 mm of length, thus being even three times as long as those living today, which rarely exceed 3 mm (Logan 1979;Álvarez & Emig 2005). e shell is variable in outline, usually subtriangular, with large interarea and wide, triangular pseudodeltidium. e hemispondylium takes the form of two prominent prongs and is supported by a small median septum (Fig. 9E). e cardinal process is large and subrectangular, extending beyond the margin. e median septum is divided forming a trifurcating structure, and the margins of interbrachial lobes are denticulated (Fig. 9G-L).
PALEOECOLOGICAL REMARKS e Brachiopoda are very abundant in the marls of Peyrère and calcareous sands of Abesse but are scarcely represented in the other five outcrops (Fig. 1). From an ecological point of view the outcrops of the Upper Oligocene of the Aquitaine Basin can be divided into four main groups (Lozouet 2004): a shallow-water calcareous facies outcropping in the vicinity of Dax (Abesse, Bezoye, Estoti), a muddy sand assemblages (Escornebéou, Bélus), a mud assemblage localized in the paleocanyon and the Peyrère fauna. e shallow-water calcareous facies contains numerous faunistic elements of the littoral zone indicating the proximity of the shore line; otherwise the assemblage is particularly rich in macro-fossils (molluscs, hermatypic corals, bryozoans, serpulids). e muddy sand assemblages are characteristic of the sublittoral zone  et al. 2006), is usually very low in most Cenozoic brachiopod populations (Taddei Ruggiero & Bitner 2008), as here. Among 1466 specimens examined 59 specimens (4.0%) were drilled (see Table 10). Such a low frequency may be explained by the fact that brachiopods are not the prime target where molluscs are very abundant. Drillings were observed on Terebratulina retusa, Megathiris detruncata, Joania cordata, J. peyrerensis n. sp. and Lacazella mediterranea. No drilling predation was observed on Novocrania anomala, Argyrotheca cuneata, A. bitnerae or Megerlia truncata. Taxonomic selectivity for particular species is difficult to explain and does not depend on amount of specimens. Drill holes were found on ventral and dorsal valves but the dorsal valve was drilled at a higher frequency (see Table 10); in two specimens drill holes occur on both valves (Fig. 10). Drill holes on calcareous exoskeletons are for the most part due to two families of gastropods: Naticidae Guilding, 1834 and Muricidae Rafinesque, 1815(Carriker & Yochelson 1968. Drilling predation is known also in the scavenger family Nassariidae Iredale, 1916 (but it is exceptional) and in the Cassidae Latreille, 1825, which feed exclusively upon echinoderms (Riedel 1995). Naticidae and Muricidae are widespread in the Upper Oligocene of the Aquitaine Basin but the Naticidae are less common, being infaunal gastropods more common

Species
Number undrilled

Drilled on both valves
Novocrania anomala (Müller, 1776) 12 0 (0.0%) 0 0 0 Terebratulina retusa (Linnaeus, 1758) 101 8 (7.3%) 3 5 0 Megathiris detruncata (Gmelin, 1791) 401  Bitner M. A. et al. in littoral sandy deposits. In the outcrop of Peyrère where the Brachiopoda are especially common and very well preserved a bulk sample has permitted us to obtain 413 species of gastropods (Lozouet 2004) including two species of Naticidae (36 specimens) and 19 species of Muricidae (133 specimens). e Muricidae generally feed upon sedentary epifaunal prey and the Naticidae only bore when the prey is buried in sediment. It is possible to differentiate boreholes produced by Muricidae or by Naticidae based on morphological criteria. e bore hole of Naticidae is neat and circular with a wide conical shape while those of Muricidae are more irregular; the hole is also straight-sided, or tapers slightly inwards (Taylor 1970). e holes reported in the studied brachiopod shells correspond clearly to muricid attacks (Fig. 10A, D-L). is is in good agreement with ecology of brachiopods and muricids, and diversity of muricids in the Peyrère outcrop.

STABLE ISOTOPE ANALYSIS
Brachiopods secrete a shell in oxygen isotopic equilibrium with surrounding seawater (Carpenter & Lohmann 1995;Buening & Spero 1996;Buening 2001;Brand et al. 2003). As their shell, composed of low-Mg calcite, is resistant to diagenesis they are good fossils for isotopic studies and are often used as a proxy for the environmental conditions of an ancient ocean (Brand et al. 2011). Carbon isotopic equilibrium in brachiopod shells is still uncertain and needs further investigations (Buening 2001;Brand et al. 2003).
For isotope analysis the three most abundant taxa in the studied species assemblage were chosen, Terebratulina retusa, Megathiris detruncata and Lacazella mediterranea. Under a scanning electron microscope (SEM) their shells appear to be very well preserved, suggesting that this material is suitable for istopic studies. e δ 18 O values of M. detruncata range from -0.41 to -0.03‰ PDB (mean -0.24‰ PDB), of L. mediterranea from -2.70 to 0.07‰ PDB (mean -1.29‰ PDB) and of T. retusa from -0.55 to -0.25‰ PDB (mean -0.40‰ PDB). e δ 13 C values of M. detruncata range from -0.82 to 2.55‰ PDB (mean 1.27‰ PDB), of L. mediterranea from -4.95 to 0.79‰ PDB (mean -1.30‰ PDB) and of T. retusa from 1.09 to 1.66‰ PDB (mean 1.37‰ PDB). Plots δ 18 O versus δ 13 C values for those species are shown in the Fig. 11. e results display substantial variability, with five samples of L. mediterranea having clearly more negative values than other samples. As both species, M. detruncata and L. mediterranea live in similar ecological conditions, possible explanations of those large differences in the isotopic values can comprise unrecognized diagenetic effects, different skeletal ultrastructures or vital effects. δ 13 C values can be additionally affected by dissolved inorganic carbon. Nevertheless, a major difference in δ 13 C values in co-occurring brachiopod species was already reported (Buening et al. 1998).
e shell in thecideide brachiopods is composed almost entirely of the microgranular primary layer. In the shell of terebratulides the primary layer constitutes a thin, outer layer, while the fibrous secondary layer dominates and this latter layer incorporates oxygen in isotopic equilibrium with the ambient seawater (Carpenter & Lohmann 1995;Buening 2001;Brand et al. 2003). e primary layer is considered to be precipitated out of the equilibrium with the seawater (Carpenter & Lohmann 1995;Buening 2001), however, Brand et al. (2003 in their detailed work on geochemistry of modern brachiopods concluded that the ecideida, although built of the primary layer, incorporate oxygen isotopes in equilibrium with the ambient sea water. In turn, vital effects refer to the fact that some organisms may biologically control the incorporation of isotopes into skeletal calcium carbonate, thus precipitating shells in isotopic disequilibrium with surrounding seawater. ese preliminary results of isotopic analyses are difficult to interpret at the moment and more studies, especially investigation of diagenetic effects, are necessary. Nevertheless   -Rage et al. 1993;Lozouet 2004). A similar discrepancy between temperatures obtained from paleontological and isotopic sources was observed by Latal et al. (2006) for the Middle Miocene sea of the Central Paratethys, thus they proposed for coastal environments the higher δ 18 O value of +1‰ SMOW; this value is characteristic for the Mediterranean Sea, for instance. Using this value they obtained temperatures that fit well with other paleotemperature proxies.
Although the Upper Oligocene sea of the Aquitaine Basin cannot be compared with the epicontinental sea of the Central Paratethys, the Aquitaine Basin constituted during the Oligocene a narrow embayment, having character of marginal, nearshore environment with reduced exchange with the ocean.
us, when assuming a value of +1‰ SMOW for the Oligocene sea in the Aquitaine Basin the paleotemperatures calculated for M. detruncata vary from 21 to 23°C, and for T. retusa from 22 to 24°C. ese temperatures fit much better with the paleoenvironmental interpretation based on faunal data. Because in marginal, nearshore marine settings the isotopic composition of seawater can be influenced by different factors (mostly evaporation and freshwater input) a combination of several independent methods, including isotopes, should be applied for a paleotemperature interpretation as presented by Latal et al. (2006) andNehyba et al. (2008) e latter species has been described as a new taxon. Two species, Megathiris detruncata and Lacazella mediterranea dominate in the studied assemblage, constituting more than 80% of the material. All species, except M. detruncata and L. mediterranea, are reported for the first time from this region; however, the presence of the genus Argyrotheca without specific attribution was already announced (Lozouet 2004). e occurrence in the studied assemblage of Novocrania anomala, Terebratulina retusa, Argyrotheca cuneata, A. bitnerae, Joania cordata, and Megerlia truncata extends the stratigraphical range of those species from the Miocene to the Oligocene. In the case of Joania and Megerlia there are the oldest occurrences of those genera. e species composition in particular localities differs considerably. e most diverse localities are Peyrère and Bélus where nine and six species were found, respectively. It may be explained by the peculiarity of the paleoenvironment in the region of Peyrère and Bélus. Both outcrops are located near the head of the paleocanyon with abundance of hard substrates and cryptic habitats, suitable environment for megathyridid and thecideide brachiopods. e two localities of Escornebéou and St-Étienne-d'Orthe show the lowest diversity with one species only. In the region of Dax five species were recognized. e Chattian brachiopods contain one form potentially endemic to the Aquitaine Basin, J. peyrerensis n. sp. and other species having wide stratigraphical and geographical range. In taxonomic composition the brachiopod fauna from the Aquitaine Basin displays low affinity with preceding Eocene faunas (e.g. Davidson 1870;Fabiani 1913;Calzada et al. 1988;Bitner 2000;Bitner & Dieni 2005;Bitner & Dulai 2008;Dulai et al. 2010;Dulai 2011;; only two species, M. detruncata and L. mediterranea are in common. In the Eocene, like the Oligocene, megathyridids dominate, with M. detruncata and numerous species of Argyrotheca represented, however, by different species than those in the Oligocene. ere are also few species of craniid brachiopods, rhynchonellides represented by the genera Erymnaria Cooper, 1959 andStreptaria Cooper, 1959, and shortlooped terebratulides like Gryphus and Leymerithyris Calzada, 1988. Restricted to the Eocene seemed to be two micromorphic cancellothyrids, Terebratulina tenuistriata (Leymerie, 1846) and Orthothyris pectinoides (von Koenen, 1894), however, recently the latter species has been found in the Lower Oligocene deposits of eastern Germany (Müller 2011b).
In turn, there is a great resemblance of the investigated brachiopod fauna to the Miocene faunas of the Mediterranean Province and Central Paratethys. Apart from J. peyrerensis n. sp., all species described here are known from one or both of these regions (e.g., Davidson 1864Davidson , 1870Dreger 1889;Zilch 1934;Julien 1940;Bărbulescu & Rado 1984;Gaetani & Saccà 1985;Marras & Ventura 1985;Bitner 1990Bitner , 1993Taddei Ruggiero 1994;Bitner & Pisera 2000;Bitner & Dulai 2004;Logan et al. 2004;Dulai 2007Dulai , 2010aBitner & Schneider 2009). Lacazella mediterranea common in the Miocene of the Mediterranean region (Davidson 1864;Julien 1940;Pajaud 1974;Logan et al. 2004) was not found in the Central Paratethys. e only thecideide brachiopod recognized in the Paratethys was ecidellina omson, 1915 from Bulgaria (Bitner 1993). Argyrotheca bitnerae described originally from the Miocene of the Central Paratethys (Dulai & Stachacz 2011) is recorded from the Oligocene of the Aquitaine Basin (this paper) but was not found in the Mediterranean province. e low affinities to the Eocene brachiopod faunas may be explained by the dramatic changes in the paleogeographical and paleoenvironmental conditions in Europe at the Eocene/Oligocene boundary, provoked by plate tectonic movements and formation of the Alpine chain (Meulenkamp & Sissingh 2003;Ivany et al. 2003). In the earliest Oligocene the origin of the Paratethys began, and till the Middle Miocene two distinct basins, the Mediterranean Sea and the intercontinental Paratethys Sea in the North, existed. A drop of sea level and climatic cooling in the early Oligocene had a significant effect on a variety of most taxonomic groups (see Berggren & Prothero 1992;Dockery & Lozouet 2003); many forms became extinct and many new taxa appeared for the first time, and a similar pattern is visible among brachiopods. In the late Oligocene the climate again became warm (tropical to subtropical) and remained warm through the Miocene (Lauriat-Rage et al. 1993).
e Recent Mediterranean and Atlantic brachiopod faunas are clearly a continuation of those Oligocene-Miocene faunas as shown by the fact that seven of nine species described here are still living in the Mediterranean Sea and/or north-eastern Atlantic (Logan 1979(Logan , 1993(Logan , 2007Logan et al. 2004;Álvarez & Emig 2005).