Xabier Murelaga

Taphonomy of the Late Cretaceous dinosaur-bearing beds of the Laño Quarry (Iberian Peninsula)

Abstract The Lano quarry, located in the northern part of the Iberian Peninsula (Basque–Cantabrian Region), has yielded a diverse continental vertebrate assemblage from the Late Cretaceous (late Campanian to early Maastrichtian). The fossil assemblage consists of almost 40 species, including bony fish, amphibians, lizards, snakes, turtles, crocodilians, dinosaurs, pterosaurs and mammals. Lano is the most productive European vertebrate locality hitherto known from the Late Cretaceous. The sedimentology of the Lano section shows that the three associated fossiliferous beds (known as L1A, L1B and L2) were deposited in an alluvial system composed primarily of fluvial sands and silts. The sedimentary structures are consistent with channel areas within an extensive braided river. The L1A level was excavated in detail and mapped following a square-metre grid system. The main features of the multispecies vertebrate assemblage are as follows: wide range of body size (including microfossils); large proportion of adult individuals; rare articulated skeletal parts; size-sorting and dominance of small elements; high spatial density; long bones showing some preferential orientation; variable dip; variable degree of breakage and large proportion of splintering; wide range of weathering and abrasion; no evidence of predatory activity or chemical alteration. On the basis of these features, we suggest that the Lano association lies between the taphonomic modes for attritional vertebrate assemblages in fluvial channels, though it tends more toward the channel-fill than the channel lag mode. The L1A sample of Lano is a heterogeneous assemblage of elements ranging from isolated bones and teeth to articulated skeletons with allochthonous and para-autochthonous characteristics. It consists of a mixture of vertebrates from different palaeocommunities, and includes aquatic (or semi-aquatic) elements and remains transported from a variety of habitats on the alluvial plain. The dinosaur bones are commonly broken and show a greater degree of abrasion than those of freshwater vertebrates, indicating that they may be allochthonous. However, actinopterygians, amphibians, pleurodiran turtles and eusuchian crocodilians are interpreted as being para-autochthonous. Palaeobatrachid frogs, bothremydid turtles and alligatoroid crocodilians are the most relatively abundant vertebrates of the Lano fossil assemblage. The occurrence of pelomedusid turtles and crocodilians is indicative of an intertropical, warm climate.

Une faune très diversifiée du Pléistocène inférieur de la Sierra de Quibas (province de Murcia, Espagne)

The Quaternary karstic site of Sierra de Quibas (Abanilla, province of Murcia, Spain) has provided a wide faunal list with more than 60 species. The assemblage of the taxa Arvicola deucalion, Castillomys rivas rivas, Eliomys intermedius, Equus altidens, Capra sp. aff. C. alba and cf. Praeovibos allows the correlation with other Spanish Lower Pleistocene sites in the Betic Cordillera, as Plines 1, Orce 3 and Venta Micena. Therefore Quibas can be located between 1.3 and 1.0 Ma. The palaeoenvironmental features of the area around the karstic cavity and the palaeoclimatic regime are inferred.

First evidence of Macaca sylvanus (Primates, Cercopithecidae) from the Late Pleistocene of Lezetxiki II cave (Basque Country, Spain)

a Sociedad de Ciencias Aranzadi, Zorroagagaina 11, 20014 Donostia-San Sebastian, Spain Departamento de Estratigrafia y Paleontologia, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, Facultad de Ciencia y Tecnologia, Apartado 644, Bilbao, Spain Departamento de Geografia, Prehistoria y Arqueologia, Universidad del Pais Vasco/Euskal Herriko Unibersitatea, Tomas y Valiente s/n, 01006 Vitoria-Gasteiz, Spain

Beachrock formation in temperate coastlines: Examples in sand-gravel beaches adjacent to the Nerbioi-Ibaizabal Estuary (Bilbao, Bay of Biscay, North of Spain)

Beachrocks are coastal sedimentary formations resulting from a relative rapid cementation of beach sediments by the precipitation of carbonate cements. These lithified structures are not usually observed at temperate settings. The present work is focused on the occurrence of a significant intertidal cementation in sand-gravel beaches formed among 43°N latitude coastline, close to the Nerbioi-Ibaizabal estuary (Bilbao, Bay of Biscay, North of Spain). Raman micro-spectroscopy combined with SEM-EDX analyses and petrographic descriptions have been applied for the determination of the cement generations and the cemented materials compositions of the beachrock outcrops. In general terms, the cements described were: Cement Generation 1 (CG 1, aragonite, high-magnesium calcite and silicate mixtures), Cement Generation 2 (CG 2, aragonite) and Cement Generation 3 (CG 3, mixtures of CaCO(3) polymorphs and iron oxides). The rest of the interstitial porosity of the rocks appeared either empty or filled with heterogeneous cemented mixtures of previously reworked compounds. The mineralogy, the regular distribution and the isopachous character of the carbonate cements together with the accurate cementation at advanced seaward bands propose a possible marine-phreatic context for the beachrock formation. However, the impure cements and the materials covering the interstitial porosity seem to be the result of both, the weathering actions consequences and the surface alterations of specific grains. Moreover, the presence of modern cemented materials (e.g. slag, bricks and pebbles) suggest a recent formation of the phenomenon.

Non-destructive spectrometry methods to study the distribution of archaeological and geological chert samples

The study of lithic raw materials recovered from archaeological sites offers relevant data on source catchment areas. Additionally, it can provide first hand information on artefact displacement, interchange networks and it can reflect the way in which the artefacts were employed. In order to characterize geological and archaeological chert samples and with the aim of finding an analytical fingerprint infrared and Raman spectroscopies were used for molecular analysis and X-ray Fluorescence spectrometry for elemental analysis. In this work, different chert samples coming from several localities with geological and archaeological importance from the Basque Country have been collected and analysed. As a consequence, Raman spectroscopy allowed to distinguish between alpha-quartz and moganite in chert samples without organic matter and it is suggested that the ratio of those two components is related to the source of the chert. In addition, the impurities that appear in the samples (CaCO(3), iron oxides and organic matter) can open new features to distinguish the samples and in this way, it would be possible to discuss the use and transport of the lithic artifacts from the sources to the final settlements.

Amphibians and reptiles from the Early Miocene of the Bardenas Reales of Navarre (Ebro Basin, Iberian Peninsula)

The Lower Miocene deposits of the Bardenas Reales of Navarre (NW Ebro Basin, northern Iberian Peninsula) have yielded a diverse vertebrate fauna, including remains of amphibians and reptiles. These remains occur in several localities in the Tudela Formation. The fossiliferous levels belong to the Biozones MN2b-3 (Biozones Z-A of the Ramblian, i.e., Late Aquitanian to Early Burdigalian in age). The amphibians and reptiles represent at least 13 out of 37 vertebrate species. Amphibians consist of a salamandrid urodele and two or three anurans. All the turtles are cryptodirans and consist of the chelydrid Chelydropsis apellanizi, the testudinids Ptychogaster (Temnoclemmys) bardenensis and Ptychogaster ronheimensis, and a Trionychinae indet. Squamates are represented by the anguid lizard Ophisaurus sp., a non-anguid lacertilian, an amphisbaenian, the erycine boid? Eryx sp., and indeterminate colubrids. Crocodilian remains are assigned to the basal alligatoroid Diplocynodon sp. The fossil associations of the Bardenas Reales of Navarre suggest that the vertebrates lived in the centre of an endoreic basin with stretches of water under intertropical to subtropical climatic conditions.

Shell bone histology of solemydid turtles (stem Testudines): palaeoecological implications

Lately, solemydid turtles have been repeatedly recovered as stem Testudines, indicating that they belong to neither one of the two major branches of crown turtles, the Pancryptodira and Panpleurodira. Despite their wide temporal (Late Jurassic to Late Cretaceous) and spatial (North America and Europe) distributions, solemydid turtles are not particularly well known, as exemplified by the fact that only a single skull has been described for the whole group so far. Furthermore, the palaeoecology of solemydid turtles is still contested with hypotheses ranging from semi-aquatic to terrestrial lifestyles. However, the habitat preference of stem Testudines, such as solemydids, is important to understand the evolution and early radiation of the turtle crown, which is primitively aquatic. Here we describe the shell bone microanatomy and histological microstructures of solemydid turtles using a broad sample of taxa of different ages and localities, as well as review previous histological accounts, to elucidate the palaeoecology of the group independent of the geological setting and gross anatomy of the fossil finds. Our results indicate that Solemydidae share unique histological features pertaining to their strongly ornamented shell bones, which a) in cases allow taxonomic identification of even small shell fragments and b) unambiguously corroborate a terrestrial lifestyle of its members. The latter further supports a terrestrial lifestyle preference of most representatives of the turtle stem.

The First Occurrence in the Fossil Record of an Aquatic Avian Twig-Nest with Phoenicopteriformes Eggs: Evolutionary Implications

Background We describe the first occurrence in the fossil record of an aquatic avian twig-nest with five eggs in situ (Early Miocene Tudela Formation, Ebro Basin, Spain). Extensive outcrops of this formation reveal autochthonous avian osteological and oological fossils that represent a single taxon identified as a basal phoenicopterid. Although the eggshell structure is definitively phoenicopterid, the characteristics of both the nest and the eggs are similar to those of modern grebes. These observations allow us to address the origin of the disparities between the sister taxa Podicipedidae and Phoenicopteridae crown clades, and traces the evolution of the nesting and reproductive environments for phoenicopteriforms. Methodology/Principal Findings Multi-disciplinary analyses performed on fossilized vegetation and eggshells from the eggs in the nest and its embedding sediments indicate that this new phoenicopterid thrived under a semi-arid climate in an oligohaline (seasonally mesohaline) shallow endorheic lacustine environment. High-end microcharacterizations including SEM, TEM, and EBSD techniques were pivotal to identifying these phoenicopterid eggshells. Anatomical comparisons of the fossil bones with those of Phoenicopteriformes and Podicipediformes crown clades and extinct palaelodids confirm that this avian fossil assemblage belongs to a new and basal phoenicopterid. Conclusions/Significance Although the Podicipediformes-Phoenicopteriformes sister group relationship is now well supported, flamingos and grebes exhibit feeding, reproductive, and nesting strategies that diverge significantly. Our multi-disciplinary study is the first to reveal that the phoenicopteriform reproductive behaviour, nesting ecology and nest characteristics derived from grebe-like type strategies to reach the extremely specialized conditions observed in modern flamingo crown groups. Furthermore, our study enables us to map ecological and reproductive characters on the Phoenicopteriformes evolutionary lineage. Our results demonstrate that the nesting paleoenvironments of flamingos were closely linked to the unique ecology of this locality, which is a direct result of special climatic (high evaporitic regime) and geological (fault system) conditions.

Combining Small-Vertebrate, Marine and Stable-Isotope Data to Reconstruct Past Environments

Three very different records are combined here to reconstruct the evolution of environments in the Cantabrian Region during the Upper Pleistocene, covering ~35.000 years. Two of these records come from Antoliñako Koba (Bizkaia, Spain), an exceptional prehistoric deposit comprising 9 chrono-cultural units (Aurignacian to Epipaleolithic). The palaeoecological signal of small-vertebrate communities and red deer stable-isotope data (δ13C and δ15N) from this mainland site are contrasted to marine microfaunal evidence (planktonic and benthic foraminifers, ostracods and δ18O data) gathered at the southern Bay of Biscay. Many radiocarbon dates for the Antoliña’s sequence, made it possible to compare the different proxies among them and with other well-known North-Atlantic records. Cooling and warming events regionally recorded, mostly coincide with the climatic evolution of the Upper Pleistocene in the north hemisphere.

Larachelus morla, gen. et sp. nov., a new member of the little-known European Early Cretaceous record of stem cryptodiran turtles

ABSTRACT A relatively diverse record of European Early Cretaceous pan-cryptodiran turtles has been revealed from the analysis of new specimens and from a review of previously defined taxa. However, knowledge about many of these taxa remains relatively limited. We erect the new taxon, Larachelus morla, gen. et sp. nov., on the basis of a shell from the late Hauterivian—early Barremian of the Iberian Range (Spain). The comparative study of this taxon with the continental European Cretaceous pan-cryptodiran representatives and cladistic analyses reveal L. morla to be a member of the little-known European Early Cretaceous stem Cryptodira. Stem cryptodirans have been recognized from the Early Cretaceous of several continents. The study of L. morla not only confirms the presence of this group in the Early Cretaceous of Europe, it also provides new insights into the European evolution of Pan-Cryptodira. This finding reveals greater diversity in European Early Cretaceous continental pan-cryptodires, highlighting its Hauterivian—Aptian record. This diversity is particularly relevant in the Iberian Range, where several clades of turtles whose coexistence has not been recognized in the Lower Cretaceous of any other region are identified: paracryptodiran members, stem cryptodiran turtles, and representatives of several lineages of the crown group Cryptodira. This very high diversity of continental taxa shows a wide range of morphological diversity that could be related to adaptation to different ecological niches.