Turritella

About: Turritella is a research topic. Over the lifetime, 107 publications have been published within this topic receiving 1737 citations.

Records of upwelling, seasonality and growth in stable‐isotope profiles of Pliocene mollusk shells from Florida

Abstract: Oxygen and carbon isotopic profiles across the shells of well-preserved bivalves and gastropods from the Pliocene Pinecrest Beds near Sarasota, Florida, provide detailed records of the paleoen-vironmental and paleoclimatic conditions under which these high-density shell beds accumulated, as well as offer insight into shell-growth rates and longevity. Eight turritellid gastropods were analyzed from within and surrounding two Turritella-rich beds, an upper bed within unit 2(2.5-2.0 Ma) and a lower bed situated near the top of the main shell bed, unit 6/7(3.5-2.5 Ma). Three bivalves plus another turritellid specimen from a lower horizon (middle of unit 6/7), considered to represent offshore, normal-marine conditions, were also analyzed. The isotopic profiles of all shells reflect year-round shell growth in a seasonal, subtropical to warm-temperate paleoenvironment. Cyclical patterns in δ18O reflect annual variations in water temperature which on average ranged from 15 to 24dC; minimum paleoseasonality contrasts varied from 7 to 9dC. Summer paleo-temperatures compare favorably with those detemined from ostracodes, whereas winter temperatures appear slightly cooler. Except for one pectinid specimen, temperature differences between horizons and specimens are small. Annual δ18O cycles indicate: Turritella apicalis lived longer and grew slightly faster than Turritella gladeensis; and, shell growth rates and increment formation in Mercenaria campechiensis are comparable to modern Florida populations. Coincident episodes of heavy δ18O and light δ18C in both turritellids and bivalves suggest a pattern of seasonal upwelling. This cool, nutrient-rich, upwelled water may be partially responsible for the great abundance of Pinecrest fossils. □Stable isotopes, Pliocene, Pinecrest Beds, Florida, upwelling, paleotemperature, mollusk, Turritella.

A new middle Eocene protocetid whale (Mammalia, Cetacea, Archaeoceti) and associated biota from Georgia

Abstract: A shallow-marine fossil biota was recovered from the Blue Bluff unit (formerly part of the McBean Formation) in the Upper Coastal Plain of eastern Georgia. Biochronologically significant mollusks (e.g., Turritella nasuta, Cubitostrea sellaeformis, Pteropsella lapidosa) and calcareous nannoplankton (e.g., Chiasmolithus solitus, Reticulofenestra umbilica, Cribocentrum reticulatum) indicate a latest Lutetian-earliest Bartonian age, or about 40 to 41 Ma. Georgiacetus vogtlensis new genus and species is described from a well-preserved, partial skeleton. Georgiacetus is the oldest known whale with a true pterygoid sinus fossa in its basicranium and a pelvis that did not articulate directly with the sacral vertebrae, two features whose acquisitions were important steps toward adaptation to a fully marine existence. The posterior four cheek teeth of G. vogtlensis form a series of carnassial-like shearing blades. These teeth also bear small, blunt accessory cusps, which are regarded as being homologous with the larger, sharper accessory cusps

Predation in time and space; drilling in the gastropod Turritella

Abstract: The intensity of drilling predation was studied on samples of fossil and Recent species of Turritella, a soft-bottom mesogastropod mollusc. Our data and records in the literature show that the frequency of drilling has remained about the same from the Eocene to the present. There may have been less predation by drilling during the Late Cretaceous. Among living Turritella, there is a sharp increase in intensity of drilling predation from the temperate zones to the tropics. This latitudinal trend is paralleled by an equatorward increase in number of species of drilling gastropods. Strong spiral ribs of some Eocene, Miocene, and Recent species of Turritella confer protection against drilling, but the mechanism of this immunity remains unclear.

Winter and summer temperatures of the early middle Eocene of France from Turritella δ18O profiles

Abstract: The mean annual range of temperature is, from a climatological point of view, at least as important as the mean annual temperature. In order to examine intra-annual temperature variations in the warm early Cenozoic, we have analyzed stable oxygen and carbon isotopes along the transect of growth on excellently preserved specimens of the gastropod Turritella imbricataria and the bivalve Venericardia imbricata from sedimentary rocks of early middle Eocene age (ca. 46 Ma) in the Paris basin. Turritella shell growth is fast throughout the year, and the isotopic records give the first detailed information about early middle Eocene seasonal variations. The oxygen isotope profiles indicate winter temperatures of about 14 °C and summer temperatures of up to 28 °C, i.e., a seasonality indistinguishable from the present situation but an annual temperature some 10 °C higher. Our results contradict the opinion that the climate during this period was more “equable” than that of today.