At the crossroads: early Miocene marine fishes of the proto-Mediterranean Sea

Connectivity and climate control fish distribution today as well as in the geological past. We present here the Aquitanian (early Miocene) marine fish of the Mesohellenic Basin, a restricted basin at the border between the proto-Mediterranean and Paratethyan seas. Based on fish otoliths, we were able to identify 19 species from 17 genera, including two new species: Ariosoma mesohellenica and Gnathophis elongatus. This fish assemblage, in conjunction with the accompanying molluscan assemblage, indicates a variable shelf paleoenvironment with easy access to the open ocean. Although available data on the Indo-Pacific fishes of the early Miocene are very limited, the fish fauna of the Mesohellenic Basin has many elements in common with the North Sea, the NE Atlantic, and the Paratethys.

Temporal change in molluscan assemblages (bivalves and gastropods) of Frobisher Bay, Nunavut, Canada, over fifty years

Long-term studies provide an effective way to assess the ecological impacts of decades-long environmental change in Arctic coastal benthic environments but are undertaken rarely in the Canadian Arctic. In light of this, historical datasets can be compared with modern samples to examine temporal differences in benthic community structure. Frobisher Bay, Nunavut provides a unique opportunity to use a historical census to examine the impacts that long-term environmental change have had on the marine benthos. Between 1967-1976 and in 2016, infaunal samples were collected in inner Frobisher Bay and were compared to determine how the molluscan assemblages have changed between the two time periods. Molluscan assemblages in two regions of inner Frobisher Bay (Iqaluit and Cairn Island) were examined to minimize sampling discrepancies between the two time periods. A long-term increase in mean annual air temperature and a decline in the length of the ice cover season were observed. Both regions exhibited some change in sediment composition and quality and in molluscan assemblage between the two time periods and species diversity indices also indicated some change between time periods. Both the 1967-1976 and 2016 molluscan datasets provide a baseline for future long-term studies in a changing Arctic.

A new molluscan assemblage from the pre-evaporitic Messinian of Crete (Greece)

<p>The Messinian Salinity Crisis (MSC) was an environmental perturbation with dramatic environmental consequences that greatly affected marine organisms. Messinian deposits are found in several locations around the Mediterranean, but few offer marine faunas rich in molluscs. A section near Heraklion, central Crete, has provided new material that contains a well preserved and rich molluscan fauna that includes many micromorphic species. The section is of early Messinian age, belongs to Agios Miron Formation, and bears several layers of fossiliferous marly sands.</p><p>Molluscs from a fossiliferous bed of the section are presented here for the first time. Gastropods and bivalves are most common, but scaphopods and chitons are not infrequent. The assemblage seems to be composed of transported elements from nearby environments and the most frequent species are present in comparable abundances for gastropods and bivalves. The gastropod fauna is represented by <em>Bittium</em> sp. and <em>Gibbula </em>sp., accompanied by <em>Diodora</em> cf. <em>graeca</em>, <em>Turritella</em> sp., <em>Jujubinus</em> sp., species of Pyramidellidae and rarer <em>Homalopoma</em> sp. and Haliotis sp. The presence of <em>Bittium</em> sp. together with <em>Jujubinus</em> sp. suggests vegetated environments. Bivalves are represented by species dwelling mostly in sandy environments such as <em>Glycymeris</em> cf. <em>inflata</em> (also occurring in larger specimens), <em>Spisula</em> sp., <em>Timoclea</em> sp. and various cardiids. Exceptionally well-preserved chitons indicate the presence of hard substrates such as rocks, pebbles or roots of seagrass beds. This is confirmed by the presence of the gastropods <em>Diodora</em> cf. <em>graeca</em> and <em>Haliotis</em> sp.</p><p>The assemblage points towards normal salinity shallow marine conditions of sandy bottoms with patches of seagrass-type vegetation before the onset of the MSC.</p>

First occurrence of Cardilia michelottii Deshayes, 1844 (Bivalvia, Cardiliidae) in the Iberian Pliocene

The family Cardilidae groups a small number of bivalve species from the superfamily Mactroidea, which have been scarcely found and have a known stratigraphic range from the middle Eocene to the present day. From these stand out Cardilia michelottii Deshayes, 1844, as an extinct valid species only previously knew from the Italian Peninsula, where it has been recorded from the Miocene of Emilia-Romagna, the Pliocene of Tuscany and Piedmont, and the Pleistocene of Lazio. The first finding of this species outside the Italian ranges is here reported from a single, but well-preserved left valve collected from the lower Piacenzian molluscan assemblage of Vale de Freixo fossil site (Pombal, West Portugal), in the Pliocene Mondego Basin. This allows to extend the known biogeographic range of this thermophilic species to the Iberian Peninsula, and also to reduce the geographical gap between the Neogene to present-day West African and Mediterranean occurrences of this morphologically very distinctive genus of warm shallow-water bivalve assemblages. Resumen La familia Cardilidae agrupa un pequeño número de especies de bivalvos de la superfamilia Mactroidea, que apenas se han encontrado de forma muy rara y tienen un rango estratigráfico conocido desde el Eoceno medio hasta nuestros días. De estos se destaca Cardilia michelottii Deshayes, 1844, como una especie extinta válida que antes solo se conocía en la Península Italiana, donde se registró desde el Mioceno de Emilia-Romaña, el Plioceno de Toscana y Piamonte y el Pleistoceno de Lazio. Se reporta el primer hallazgo de esta especie fuera de los rangos de Italia, a partir de una valva izquierda bien conservada que ha sido recolectada en la asociación de moluscos fósiles del Piacenziese inferior del yacimiento de Vale de Freixo (Pombal, Oeste de Portugal), en el Plioceno de la Cuenca del Mondego. Esto hallazgo permite extender el rango biogeográfico conocido de esta especie termofílica hasta la Península Ibérica, así como reducir el espacio sin citas entre las ocurrencias oeste-africanas y mediterráneas de este género morfológicamente muy distintivo y que integra asociaciones de bivalvos de aguas cálidas y poco profundas.

Calling Time on Oronsay: Revising Settlement Models Around the Mesolithic–Neolithic Transition in Western Scotland, New Evidence from Port Lobh, Colonsay

For over 120 years, the shell middens of western Scotland and the series of open-air sites on Oronsay have been the focus of debate in European Mesolithic studies. This paper challenges the significance of Oronsay in light of results from the geophysical survey and test-excavation of a new limpet and periwinkle shell midden dated to the late 5th or start of the 4th millennium cal bc at Port Lobh, Colonsay that offers fresh evidence to re-evaluate critically the role of Oronsay and coastal resources in island settlement models ahead of the Mesolithic–Neolithic transition. Test excavations recovered a marine molluscan assemblage dominated by limpet and periwinkle shells together with crab, sea urchin, a fishbone assemblage composed mainly of Gadidae, some identifiable bird and mammal bone, carbonised macroplant remains, and pumice as well as a bipolar lithic assemblage and coarse stone implements. Novel seasonality studies of saithe otolith thin-sections suggest wintertime tidal fishing practices. At least two activity events may be discerned, dating from the late 5th millennium cal bc. The midden could represent a small number of rapidly deposited assemblages or maybe the result of stocastic events within a more extended timeframe. We argue that alternative research questions are needed to advance long-standing debates about seasonal inter-island mobility versus island sedentism that look beyond Oronsay to better understand later Mesolithic occupation patterns and the formation and date of Oronsay middens. We propose alternative methodological strategies to aid identification of contemporaneous sites using geophysical techniques and lithic technological signatures.

NEW MOLLUSCAN RECORDS AND PALAEOECOLOGY OF THE LATE PLEISTOCENE MARINE ASSEMBLAGE FROM LA CORONILLA (ROCHA, URUGUAY) /NOVOS REGISTROS E PALAEOECOLOGIA DE MOLUSCOS DA ASSOCIAÇÃO MARINHA PLEISTOCÉNICA DE LA CORONILLA (ROCHA, URUGUAI)

The Late Pleistocene marine molluscan assemblage from La Coronilla is one of the richest Quaternary marine deposit from Uruguay. This contribution represents an update of the bivalve and gastropod species composition of this deposit and includes a palaeoecological analysis of the molluscan fauna. The ecological preferences of the recorded species allowed the reconstruction of the palaeoenvironmental conditions of the eastern Uruguayan coast and the palaeobiogeographic scenario of the area during the Late Pleistocene. The fossil assemblage of La Coronilla contains 91 bivalve and gastropod taxa of which 28 are new to this deposit and 11 are first reported for the Uruguayan Quaternary marine assemblages. The latest are Turbonilla abrupta, Turbonilla cf. farroupilha, Turbonilla brasiliensis, Turbonilla cf. deboeri, Turbonilla penistoni, Turbonilla turris, Olivella defiorei, Eurytellina angulosa, Kellia sp., Paraleptopecten bavayi, and Pandora sp. Almost all recorded species from the assemblage are marine and live in soft bottoms, although hard/consolidated substrate species and microgastropods that live in ecological interaction with other invertebrate taxa were also found. The high percentage of tropical-subtropical species, the absence of cold-water species, and the record of extralimital warm water northern species, adds new evidence for the inference of warmer than present conditions in the Uruguayan coast during the Late Pleistocene. ResumoA associação de moluscos marinhos do Pleistoceno Superior de La Coronilla é um dos mais ricos depósitos marinhos Quaternários do Uruguai. Esta contribuição representa uma revisão da composição de espécies de bivalves e gastrópodes deste depósito e inclui uma análise paleoecológica da fauna de moluscos. As preferências ecológicas das espécies registradas permitiram a reconstrução das condições paleoambientais da costa leste uruguaia e do cenário paleobiogeográfico da área durante o Pleistoceno Superior. A associação fóssil de La Coronilla contém 91 taxa de bivalves e gastrópodes, dos quais 28 são novos neste depósito e 11 são relatados pela primeira vez nas associações marinhas quaternárias uruguaias. São elas Turbonilla abrupta, Turbonilla cf. farroupilha, Turbonilla brasiliensis, Turbonilla cf. deboeri, Turbonilla penistoni, Turbonilla turris, Olivella defiorei, Eurytellina angulosa, Kellia sp., Paraleptopecten bavayi e Pandora sp. Quase todas as espécies registradas na associação são marinhas e vivem em fundos constituídos por sedimentos móveis, embora também sejam encontradas espécies de substratos duros/sedimentos consolidados e microgastrópodes que vivem em interação ecológica com outros taxa de invertebrados. A alta percentagem de espécies tropicais-subtropicais, a ausência de espécies de água fria e o registro de espécies que com habitats não limitados às águas quentes do norte, constituem novas evidências da ocorrência de condições mais quentes do que as atuais na costa uruguaia durante o Pleistoceno Superior.