During Eocene times the Pyrenean area may have played an important role as a paleobiogeographic link between the Western Tethys and the North Atlantic domains. However, its marine faunas are still poorly documented. This paper presents the results of a first study on the mid-upper Eocene (Lutetian to Priabonian) marine macrofossils of Navarre included in the paleontological collection of Maximo Ruiz de Gaona, a researcher whose studies on the geology and paleontology of this territory constitute an obligatory historical reference. The described fossils come from the Eocene marly formations of the Pamplona basin and the Urbasa-Andia limestone Formation and overlying deposits, in the Estella-Urbasa area, west of the Pamplona fault. Some of the specimens studied come from outcrops that do not exist any longer. This fact increases the interest of conservation and the study of this collection. The paleontological data from the Estella-Urbasa area are almost entirely new. This study has allowed the description of 24 taxa of marine macrofauna. Seven of them -Cyclolitopsis patera, Funginellastraea barcelonensis, Pycnodonte rarilamella, Metacrinus sp., Triplacidia sp., in addition to an indeterminate Cyclostomatida bryozoan and an indeterminate Serpulidae annelid- are new to the fossil record of Navarre. The macropaleontological associations described in this and previous works are not as diverse as those from other coeval European geo-logical regions. In addition to possible ecological conditions, sampling biases and, above all, taphonomic biases, specifically the loss of invertebrate species with aragonite skeletons, arise as the main explanation.

Durante el Eoceno el área pirenaica pudo desempeñar un papel importante como encrucijada paleobiogeográfica entre los dominios del Tetis occidental y el Atlántico norte. Sin embargo, sus faunas marinas están todavía poco documentadas. En este trabajo se presentan los resultados de un primer estudio sobre los macrofósiles marinos del Eoceno medio–superior (Luteciense–Bartoniense–Priaboniense) de Navarra de la colección paleontológica de Máximo Ruiz de Gaona, investigador cuyos estudios sobre la geología y paleontología de este territorio constituyen una referencia histórica obligada. Los fósiles descritos provienen de las formaciones margosas del Eoceno de la cuenca de Pamplona y de la Formación Calizas de Urbasa-Andia y niveles suprayacentes, en el área de Estella-Urbasa, al oeste de la falla de Pamplona. Algunos de los especímenes estudiados provienen de afloramientos ya desaparecidos, circunstancia que aumenta el interés de la conservación y estudio de esta colección. Además, los datos paleontológicos del área de Estella–Urbasa son casi del todo novedosos. Este estudio ha permitido describir 24 taxones de macrofauna marina. Siete de ellos ─Cyclolitopsis patera, Funginellastraea barcelonensis, Pycnodonte rarilamella, Metacrinus sp., Triplacidia sp., además de un briozoo Cyclostomatida y un anélido Serpulidae indeterminados─ son nuevos para el registro fósil de Navarra. Las asociaciones macropaleontológicas descritas aquí y en otros trabajos precedentes son poco diversas si se las compara con las coetáneas de otras regiones geológicas europeas. Además de posibles condicionamientos ecológicos, se plantea la existencia de sesgos de muestreo y, sobre todo de sesgos tafonómicos, en concreto, la pérdida de las especies de invertebrados con esqueletos aragoníticos, como principal explicación de este hecho.

Fossil associations from the middle and upper Eocene (Bartonian and Priabonian) sedimentary succession of the Pamplona Basin are described. This succession was accumulated in the western part of the South Pyrenean peripheral foreland basin and extends from deep-marine turbiditic (Ezkaba Sandstone Formation) to deltaic (Pamplona Marl, Ardanatz Sandstone and Ilundain Marl formations) and marginal marine deposits (Gendulain Formation). The micropalaeontological content is high. It is dominated by foraminifera, and common ostracods and other microfossils are also present. The fossil ichnoasssemblages include at least 23 ichnogenera and 28 ichnospecies indicative of Nereites , Cruziana , Glossifungites and ? Scoyenia-Mermia ichnofacies. Body macrofossils of 78 taxa corresponding to macroforaminifera, sponges, corals, bryozoans, brachiopods, annelids, molluscs, arthropods, echinoderms and vertebrates have been identified. Both the number of ichnotaxa and of species (e. g. bryozoans, molluscs and condrichthyans) may be considerably higher. Body fossil assemblages are comparable to those from the Eocene of the Nord Pyrenean area (Basque Coast), and also to those from the Eocene of the west-central and eastern part of South Pyrenean area (Aragon and Catalonia). At the European scale, the molluscs assemblages seem endemic from the Pyrenean area, although several Tethyan (Italy and Alps) and Northern elements (Paris basin and Normandy) have been recorded. Palaeontological data of studied sedimentary units fit well with the shallowing process that throughout the middle and late Eocene occurs in the area, according to the sedimentological and stratigraphical data.

Scleractinian corals produce an aragonite skeleton that is usually converted to calcite by diagenetic processes after death. However, examples that have preserved the original aragonite skeleton and its original microstructure have been found in the Igualada Basin (NE Spain). The species Desmophyllum castellolense is described and analyzed. X-ray diffraction was used to confirm the skeletal aragonite and analyze the associated elements. The microstructure of the skeleton is described using polished and thin sections with the aid of scanning electron microscopy (SEM) and optical microscopy. The description of this species is taken from Álvarez Pérez, 1993, Álvarez Pérez, 1997.

Sponges and corals from the Bartonian marly formations of the Pamplona Basin (South Pyrenean area, Navarre) are described for the first time. The fossiliferous levels correspond respectively to flood-influenced delta-front (Ardanatz Sandstone) and restricted outer-platform (Ilundain Marls Fm.) environments. The fossil sponges exhibit diagenetic fragmentation, but they are often complete specimens. The skeleton appears partially or totally replaced by calcite and/or in some cases large crystals of celestite. Celestite forms relatively early during diagenesis in a dysoxic environment. Neomorphic fibrous quartzine-lutecine spherulites are also present. Hexactinellids and lithistids occur, but the former predominate. The associations include the species Laocoetis samueli, Guettardiscyphia thiolati and/or Pleuroguettardia iberica, cf. Rhizocheton robustus, and two lithistids indet. Corals are present only in the Ardanatz Sandstone. The fossil skeletons are composed of large neomorphic sparry calcite crystals. The assigned species are Stylocoenia taurinensis, Astrocoenia octopartita, Ceratotrochus bodellei, Placosmiliopsis bilobatus, and Desmophyllum castellolense. The sponge and coral taxa are similar to those previously described from other contemporaneous geological formations of the Pyrenean realm. The Pamplona Basin assemblages appear less diverse than those of the Bartonian of the eastern South Pyrenean area, more similar to that of the Eocene of Biarritz (Aquitanian Basin). This lower diversity is not due to a lower-resolution sampling but to taphonomic bias and/or paleoecological differences. The dominance of hexactinellids, erect morphologies, and sedimentological and micropaleontological data show that the sponge communities lived in deep shelfal waters. The corals, mainly associated with levels with high terrigenous content, seem reworked from shallower and more proximal environments.

This study reports for the first time on the occurrences of deep-water coral species in the Spanish territorial waters of the Strait of Gibraltar. Based on an extensive dataset of 334 grab samples, 16 species of calcareous corals have been identified in water depths between 13-443 m. Scleractinian corals form the dominant benthic community between 140-330 m water depth. The corals appear on the seabed both as solitary individuals and as patches on small biological topographic build-ups. The most common coral species Lophelia pertusa and Madrepora oculata are associated with coarse-grained calcareous sediments and mound structures. In the shallowest part of the study area (< 150 m) algae and bryozoans are dominant and only a few coral species are observed. This zonation and the occurrence of the azooxanthellate corals in the Strait of Gibraltar relates to light availability and perhaps also to the complex interaction between the outflow of Mediterranean water and surficial inflow of Atlantic water into the Mediterranean Sea.