Rosa Domènech

In the Estepona basin (Málaga, S Spain), the richest and the most diverse Pliocene sites of marine invertebrates (mostly molluscs) of the Mediterranean are found. Most of the species described up until now (~95% out of 892 identified species) occur at the Parque Antena and the Velerín Area (Velerín, Velerín-Carretera and Velerín-Antena) sites. Although molluscs are very well known, the age of these important sites is still controversial. In this paper, a biochronological study of these sites based on an integrated study of the microfossil (calcareous nannoplankton and planktonic foraminifers) and macrofossil (molluscs) assemblages is presented. The Parque Antena and Velerín-Carretera sites can be attributed to the late Zanclean (uppermost part of the early Pliocene) based on the presence of Globorotalia margaritae, Gr. puncticulata and Gr. group crassaformis (including Gr. crassaformis s.s.). Nannoplankton assemblages agree with this age, and can be attributed to the CN11b biozone of Okada & Bukry (1980) due to the presence of small Gephyrocapsa, Sphenolithus abies and Reticulofenestra pseudoumbilica. At the Velerín-Antena section, the bioindicators of the early Pliocene Gr. margaritae, Sphenolithus abies and Reticulofenestra pseudoumbilica are absent. The molluscs found in the studied sites correlate with the Mediterranean Pliocene Molluscan Unit 1 of Raffi & Monegatti (1993) (MPMU1). Finally, the coexistence of Gr. margaritae and Gr. group crassaformis in the Mediterranean domain is described for the first time.

Se describe Protovirgularia, una pista de bivalvo, del Langhiense (Mioceno medio) de la Cuenca del Vallès-Penedès en el noroeste de España. Se distinguen tres morfotipos. Los morfotipos 1 y 2 son epirrelieves negativos con un característico patrón en espiga y pueden asignarse a la icnoespecie P. dichotoma. La estructura en espiga es el resultado de la actividad del pie bífido de un protobranquio. El morfotipo 3 (P. cf. dichotoma) se conserva como relieves completos con retrorrelleno, a techo de capas de areniscas. En ocasiones, se observa su posición sobre pistas de los otros dos tipos. Estos relieves completos pueden corresponder a la traza dejada por el paso del cuerpo del animal. El productor de Protovirgularia fue muy probablemente un nuculáceo, ya que este grupo de bivalvos sedimentívoros son muy móviles a diferencia de otros protobranquios. En el Vallès-Penedès, se han identificado varias especies de nucúlidos y nuculánidos que podrían haber producido este tipo de pistas. Sin embargo, en general, son de talla menor a la que correspondería para el productor de las trazas descritas y, además, aparecen en otro tipo de facies.

A new ichnofossil-Lagerstätte from the Miocene Vilanova Basin (NE Spain) is described. It is characterized by bioerosion structures that are exceptionally preserved as positive casts, many associated with internal and external molds of mollusk shells (gastropods and bivalves). Five main ichnotaxa were identified: Caulostrepsis contorta, C. taeniola, Entobia cateniformis, E. geometrica, and Gastrochaenolites dijugus, produced by annelids, sponges and bivalves, respectively. Combination of ichnological, taphonomical, and systematic data allows the concentration to be interpreted as the result of several storm events that mixed shells from a diverse array of marine environments during the biostratinomical phase. Bioerosive episodes took place before and after storms, and diagenetic processes produced external and internal shell molds and fine casts of the borings.

Among invertebrates and both in modern and ancient marine environments, certain echinoderms have been and are some of the most active and widespread bioturbators and bioeroders. Bioturbation and/or bioerosion of regular and irregular echinoids, starfish, brittle stars, sea cucumbers and crinoids are known from modern settings, and some of the resulting traces have their counterparts in the fossil record. By contrast, surficial trails or trackways produced by other modern echinoderms, e.g., sand dollars, exhibit a lower preservation rate and have not yet been identified in the fossil record. In addition, the unique features of the echinoderm skeleton (e.g., composition, rapid growth, multi-element architecture, etc.) may promote the production of related traces produced by the reutilization of echinoderm ossicles (e.g., burrow lining), predation (e.g., borings), or parasitism (e.g., swellings or cysts). Finally, the skeletal robustness of some echinoids may promote their post mortum use as benthic islands for the settlement of hard-substrate dwellers.

A well-preserved omission surface (sedimentary discontinuity) in an outcrop near Alcoi in southeastern Spain displays trace fossils and body fossils that reflect a dynamic benthic community during the Miocene (Langhian–Tortonian). This outcrop, besides being the type locality ofSpongeliomorpha ibericaSaporta, 1887, exhibits other abundant trace fossils, such asGlossifungites saxicavaŁomnicki, 1886 andGastrochaenolites ornatusKelly and Bromley, 1984. These trace fossils are restricted to a single stratigraphic horizon and constitute a typical firmground ichnoassemblage of theGlossifungitesichnofacies. The interiors of some of theGlossifungitesandSpongeliomorphaburrows were occupied by encrusting balanomorph barnacles (Actinobalanus dolosusDarwin, 1854). This paper is the first report of cryptic barnacles colonizing the interior of open burrows that constitute a typical firmground ichnocoenose in the fossil record. Detailed ichnologic study demonstrates that the ichnospeciesGlossifungites saxicavastands as a valid ichnotaxon and is not a synonym of the ichnogenusRhizocorallium, as has been suggested by some previous workers.

This study presents the results of a multi-proxy analysis conducted to improve our understanding of the palaeoenvironmental conditions of the freshwater and brackish marshes of Cal Maurici (Barcelona, Spain) and the human impact on them during the mid-Holocene (6171–3891 cal. yr BP). The study integrates data from pollen, phytolith, diatom, charcoal, seeds and malacological analyses and helps to reconstruct the ecological conditions during the early establishment of farming communities in western Mediterranean facade. The results indicate a landscape dominated by Mediterranean vegetation with aquatic plants in the shallow marshes and well-developed forests in the nearby area, providing for the first time in the Holocene of NE Iberian Peninsula the palaeoecological conditions of deltaic areas. Ecofactual evidence indicates an initial landscape dominated by brackish marshes (6171–5773 cal. yr BP) in which Ruppia cf. maritima was predominant and human impact was low. Between 5026 and 4839 cal yr. BP, freshwater conditions expanded with an increase in Potamogeton sp. and the presence of Typha angustifolia and Spirogyra sp. algae with well-developed oak woodlands and deciduous trees in nearby areas. The expansion of evergreen forest occurred later (from 4960 to 4825 cal. yr BP until 3712 cal. yr BP), with the decline of deciduous woodland and the expansion of evergreen oaks, pinewoods, wild olive trees and box, coinciding with a period of increased human activity in the area. Additionally, the presence of marine resources at several archaeological excavation sites and domestic plants at Cal Maurici provides an opportunity to evaluate the interaction between earlier farmers and marine or deltaic ecosystems.