International Journal of Speleology 43 (2) 175-192 Tampa, FL (USA) May 2014 Available online at scholarcommons.usf.edu/ijs/ & www.ijs.speleo.it International Journal of Speleology Off icial Journal of Union Internationale de Spéléologie The Cova des Pas de Vallgornera (Llucmajor, Mallorca): a singular deposit bearing an exceptional well preserved Early Pleistocene vertebrate fauna Pere Bover*1,2,3, Alex Valenzuela1, Carmen Guerra1, Juan Rofes4,5, Josep A. Alcover1,3, Joaquín Ginés6, Joan J. Fornós7, Gloria Cuenca-Bescós5, and Antoni Merino8 1Department of Biodiversity and Conservation, Institut Mediterrani d’Estudis Avançats (IMEDEA, CSIC-UIB), Cr. Miquel Marquès 21, 07190 Esporles, Illes Balears, Spain 2Australian Centre for Ancient DNA, University of Adelaide, North Terrace Campus, Adelaide, Australia 3Research Associate, Mammalogy Department/Division of Vertebrate Zoology, American Museum of Natural History, New York, USA 4Departamento de Estratigrafía y Paleontología, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Sarriena s/n, 48940 Leioa, Spain 5Grupo Aragosaurus-IUCA, Área de Paleontología, Departamento de Ciencias de la Tierra, Universidad de Zaragoza, 50009 Zaragoza, Spain 6Federació Balear d’Espeleologia, Palma, Illes Balears, Spain 7Departament de Ciències de la Terra, Universitat de les Illes Balears, Ctra. Valldemossa km 7,5, 07122 Palma, Illes Balears, Spain 8Grup Espeleològic de Llubí, Illes Balears, Spain Abstract: The Cova des Pas de Vallgornera is the longest cave of Mallorca (Balearic Islands, Western Mediterranean) and one of the 30 longest caves in the world. The exploration of one of the galleries allowed the discovery of a fossiliferous deposit of vertebrate remains in a remarkable preservation state. The fossil faunal complex found in this gallery is composed of up to 5 mammalian species (Myotragus aff. kopperi, Hypnomys onicensis, Nesiotites aff. ponsi, Rhinolophus aff. mehelyi and Pipistrellus sp.), at least 14 bird species (among them two Mallorcan endemic taxa: Pica mourerae and Athene vallgornerensis), one reptile (Podarcis aff. lilfordi) and one amphibian (Discoglossus sp.). This faunal composition is similar to the one recorded in the Pedrera de s’Ònix, a well known deposit from the Early Pleistocene of Mallorca, and shared morphological characteristics between taxa of both deposits suggest that the chronology of the Cova des Pas de Vallgornera should be considered Early Pleistocene as well. Both taxonomical analysis and chronology of this fauna furnished information on some speleological aspects of the cave. Keywords: paleontological deposit; Early Pleistocene; Cova des Pas de Vallgornera; Mallorca; fossil vertebrates Received 26 September 2013; Revised 13 January 2014; Accepted 4 March 2014 Citation: Bover P., Valenzuela A., Guerra C., Rofes J., Alcover J.A., Ginés J., Fornós J.J., Cuenca-Bescós G. and Merino A., 2014. The Cova des Pas de Vallgornera (Llucmajor, Mallorca): a singular deposit bearing an exceptional well preserved Early Pleistocene vertebrate fauna. International Journal of Speleology, 43 (2), 175-192. Tampa, FL (USA) ISSN 0392-6672 http://dx.doi.org/10.5038/1827-806X.43.2.6 INTRODUCTION of the island, mainly composed of limestones. More than 2,000 caves have been explored and surveyed The Balearic Islands are an archipelago located at in the island (Encinas, 2006). Exploration and the western area of the Mediterranean Sea (Fig. 1 A-B). paleontological excavation in some of these Balearic It is compound of two different groups of islands. The caves have allowed the discovery and subsequent Western set, or Pityusic Islands, consists of two main study and analysis of the fossil fauna from these islands (Eivissa [‘‘Ibiza’’] and Formentera). On the other islands. hand the Eastern set, or Gymnesic Islands, is more Different faunal assemblages have been identified in isolated than the Pityusics and constitutes of two main Mallorca, but the most relevant insular fauna has been islands (Mallorca and Menorca). The current isolation of recorded in post-Messinian deposits (e.g., Alcover et the Balearic Islands began at the end of the Messinian al., 1981). This faunal assemblage (called Myotragus- Salinity Crisis (MSC), 5.35 My ago (Gautier et al., 1994; fauna) is mainly composed of an artiodactyl, Myotragus Clauzon et al., 1996; Krijgsman et al., 1999). (Bovidae) (Bate, 1909), a rodent, Hypnomys (Gliridae) The existence of abundant caves all around (Bate, 1918) and an insectivore, Nesiotites (Soricidae) Mallorca is favoured by the geological characteristics (Bate, 1944). Although these three taxa survived during *[email protected] 176 Bover et al. all the Plio-Pleistocene, recent discoveries prove that coastal cave-system that allows to investigate complex other mammalian species colonized Mallorca during speleogenetic mechanisms and speleothem formation the Messinian, and that they became extinct during processes, many of them controlled by Quaternary sea the Pliocene and Early Pleistocene (Bover et al., 2014, level changes (e.g., Ginés et al., 2009a, 2009b; Merino and references therein). et al., 2009; Tuccimei et al., 2009; Dorale et al., 2010; In 1968, a cave known since then as Cova des Pas Fornós et al., 2010a, 2011; Merino & Fornós, 2010). de Vallgornera, and located on the southern coast In this paper we present the fossil faunal assemblage of Mallorca, at the municipality of Llucmajor, was that has been recorded through a single excavation discovered in the course of a drilling carried out for campaign carried out during May 2010 at CPV. The the construction of a cesspit. bones collected in the fossiliferous deposit provided After the initial exploration of the cave (Collignon, relevant information on the collapse of the ancient 1982), a first detailed topographic survey published natural entrance. Additionally, faunal remains also shed by Merino (1993) represents a cave with a total length light on some other aspects on the geomorphological of approximately 2 km. After the negotiation of two history of the cave and its chronology. narrow passages in 1994 and 2004, the length of the cave has been remarkably increased reaching 6.5 km METHODS in 2000 (Merino, 2000), 23 km in 2006 (Merino et al., 2006), 40 km in 2007 (Merino et al., 2007), 56 km The short time available for the excavation of the in 2008 (Merino et al., 2008), 62 km in 2009 (Gràcia deposit and the complexity of the whole excavation et al., 2009; Merino et al., 2009) and 65 km in 2011 in such a remote place of the cave precluded the use (Merino et al., 2011). Currently, more than 74 km of grid squares to locate the bones in the deposit. have been already surveyed (Merino et al., 2014) and Additionally, the main objective of the excavation was it is considered one of the 30 longest caves in the to remove the material from the surface, a rescue world (Fig. 1 C). Currently, this cave is only accessible of material for its conservation and scientific study. through the artificial entrance excavated in 1968. Therefore, the collected material was reported on a The Cova des Pas de Vallgornera (from now on CPV) is detailed topographical survey of the passage based an extensive maze cave partially drowned by brackish on landmarks of the topography and each collected phreatic waters and it lies in a tabular platform built item has been refered to its proximity to one of the 28 up by an Upper Miocene reefal limestone sequence established sections (Fig. 1 D, T1-T28). The excavation (Ginés et al., 2008; Fornós et al., 2010a, 2011, and was mainly collecting bones by hand, although the references there in). It has emerged as a conspicuous material partially covered by flowstone had to be Fig. 1. Map of the Western Mediterranean, with A: the location of the Balearic Islands, and, B: the location of CPV in the island of Mallorca. C: Schematic topographic survey of CPV, indicating the presence of complete/articulated skeletons of fossil vertebrates mentioned in the text (1. Myotragus, 2-4. Hypnomys sp.), and the location of the current entrance to the cave and the deposit. D: Detailed topographic survey of the Galeria del Tragus/Sala del Col·lapse. Topography landmarks (5000, and location of section T1 to T28) were used to locate the fossil material in the deposit. Asterisk close to T28 indicates the location of the two associated skeletons of Myotragus juveniles, whereas the star in the Sala del Col·lapse indicates the location of the articulated Myotragus skeleton (IMEDEA 103003). International Journal of Speleology, 43 (2), 175-192. Tampa, FL (USA) May 2014 The fossil vertebrates of Cova des Pas de Vallgornera 177 removed using mechanical techniques (Fig. 2.A). After tabular deposits outcrop all along the southern labelling and packaging, the materials were placed and eastern coast, shaping this flat karst region in protected containers and carried outside the cave (Fornós & Gelabert, 2004). This region must be once every day by volunteers. All bones were initially considered as a post-orogenic carbonate platform that cleaned with water without any kind of aggressive discordantly onlaps the folded Mesozoic basement mechanical tool or chemical treatment. A professional (Serres de Llevant and Serres Centrals). From a conservator (Mr Bernat Font, St Llorenç, Mallorca) sedimentological point of view, the Upper Miocene worked on a selection of bones that were embebed deposits constitute a complex reef sequence related in hard sediment and/or flowstone, or fragmented. to the well-differentiated depositional environments The cleaning of bones was done basically through a characteristics of tropical carbonate platforms, with mechanical work, although when necessary it was a wide textural variability as a function of the reef done through a chemically controlled process (see architecture related to the sea level oscillations and Diaz et al., 2014). the resulting depositional environments (Pomar et The material from CPV and from other deposits used al., 1996). This sedimentological complexity produces in this paper as comparison material is listed in Annex 1 sharp lateral and vertical changes of rock facies, (http://dx.doi.org/10.5038/1827-806X.43.2.6).