Paleontology

Late Neogene and Early Quaternary Paleoenvironmental and Paleoclimatic Conditions in Southwestern Europe: Isotopic Analyses on Mammalian Taxa Authors:1. Laura Domingo (a)2. Paul L. Koch (a)3. Manuel Hernández Fernández (b,c)4. David L. Fox (d)5. M. Soledad Domingo (e)6. María Teresa Alberdi (f)Affiliations:a. Earth and Planetary Sciences Department. University of California Santa Cruz, Santa Cruz, California, United States of Americab. Departamento de Paleontología, Universidad Complutense de Madrid, Madrid, Spainc. Departamento de Cambio Medioambiental, Instituto de Geociencias (UCM, CSIC), Madrid, Spaind. Department of Earth Sciences. University of Minnesota, Minneapolis, Minnesota, United States of Americae. Museum of Paleontology, University of Michigan, Ann Arbor, Michigan, United States of Americaf. Departamento de Paleobiología, Museo Nacional de Ciencias Naturales-CSIC, Madrid, SpainAbstract:Climatic and environmental shifts have had profound impacts on faunal and floral assemblages globally since the end of the Miocene. We explore the regional expression of these fluctuations in southwestern Europe by constructing long-term records (from ~11.1 to 0.8 Ma, late Miocene–middle Pleistocene) of carbon and oxygen isotope variations in tooth enamel of different large herbivorous mammals from Spain. Isotopic differences among taxa illuminate differences in ecological niches. The ?13C values (relative to VPDB, mean ?10.3±1.1‰; range ?13.0 to ?7.4‰) are consistent with consumption of C3 vegetation; C4 plants did not contribute significantly to the diets of the selected taxa. When averaged by time interval to examine secular trends, ?13C values increase at ~9.5 Ma (MN9–MN10), probably related to the Middle Vallesian Crisis when there was a replacement of vegetation adapted to more humid conditions by vegetation adapted to drier and more seasonal conditions, and resulting in the disappearance of forested mammalian fauna. The mean ?13C value drops significantly at ~4.2?3.7 Ma (MN14–MN15) during the Pliocene Warm Period, which brought more humid conditions to Europe, and returns to higher ?13C values from ~2.6 Ma onwards (MN16), most likely reflecting more arid conditions as a consequence of the onset of the Northern Hemisphere glaciation. The most notable feature in oxygen isotope records (and mean annual temperature reconstructed from these records) is a gradual drop between MN13 and the middle Pleistocene (~6.3?0.8 Ma) most likely due to cooling associated with Northern Hemisphere glaciation.

As many of you know, here in the lab we have a thing for rare stuff out of the Niobrara chalk. We've found the only articulated skeleton of Protosphyraena, described the giant filter-feeder Bonnerichthys, we make a habit of collecting excellent cephalopod mouthparts like Spinaptychus and Rugaptychus, and even discovered the only open coiled ammonite out of the whole formation. So when it comes to new giant coelacanths out of Kansas, yeah we're on that too!The second specimen (left) with a cast of the left lower jaw of the first specimenThe first specimen of Megalocoelacanthus from Kansas was prepared by our lab in 2005. It was given the name "mystery fish" since the bones looked nothing like what we usually work with. The bone quality was pretty nice, and comprised a nearly complete skull. It was eventually identified by Dr. Ken Carpenter (at the Denver Museum at the time) as a coelacanth, and the specimen went off to a repository.Sculpting a body with the Vienna Latimeria specimen blown up to sizeWhile preparing and molding the specimen, I discovered a second specimen in 2007 much higher in the chalk consisting of a left lower jaw. As far as we know, these are the only two specimens of Megalocoelacanthus ever discovered in 150 years of paleontological prospecting in the entire Niobrara.Side fiew of the unpainted and almost finished prototypeFrom past projects, it is obvious that we are the only people crazy enough to do 3d restorations of Kansas fish. We had disarticulated casts of the whole head of this giant coelacanth, so why not attempt a restoration?No teeth, but it could nearly swallow me whole with that mawWell, here's our first stab at it. In the future we're going to have to un-flatten the mandibles so they better fit the floor of the mouth. One thing is for sure though: it's still a strange fish even when all put together.

Phylogeny vs Time Oceanic Upwelling Locales Mosasaur Fossil LocalesPhysical Drivers of Mosasaur EvolutionAuthors:1. Michael J. Polcyn (a)2. Louis L. Jacobs (a)3. Ricardo Araújo (a, b)4. Anne S. Schulp (c, d)5. Octávio Mateus (b, e)Affiliations:a. Roy M. Huffington Department of Earth Sciences, Southern Methodist University, Dallas, Texas 75275, USAb. Museu da Lourinhã Rua João Luis de Moura, 95. 2530–158 Lourinhã, Portugalc. Natuurhistorisch Museum Maastricht, de Bosquetplein 6–7, NL-6211 KJ Maastricht, The Netherlandsd. Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, The Netherlandse. Departamento de Ciências da Terra, FCT, Universidade Nova de Lisboa, Lisbon, PortugalAbstract:Mosasaurs are marine squamates with a 32.5 million-year history from their appearance at 98 Ma to their extinction at the K-Pg boundary (65.5 Ma). Using a database of 43 generic and 94 species-level taxa, we compare the taxonomic diversity and patterns of morphological disparity in mosasaurs with sea level, sea surface temperature, and stable carbon isotope curves for the Upper Cretaceous to explore factors that may have influenced their evolution. No single factor unambiguously accounts for all radiations, diversification, and extinctions; however, the broader patterns of taxonomic diversification and morphological disparity point to niche differentiation in a “fishing up” scenario under the influence of “bottom-up” selective pressures. The most likely driving force in mosasaur evolution was high productivity in the Late Cretaceous, driven by tectonically controlled sea levels and climatically controlled ocean stratification and nutrient delivery. When productivity collapsed at the end of the Cretaceous, coincident with bolide impact, mosasaurs became extinct.

Where, what is and what will be.

A new Late Triasssic phytogeographical scenario in westernmost GondwanaAuthors:1. Silvia N Césari (a)2. Carina E Colombi (b)Affiliations:a. Museo Argentino de Ciencias Naturales, ‘B. Rivadavia’, Department of Palaeobotany, Avenida Ángel Gallardo 470, Buenos Aires 1405, Argentinab. Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, San Juan 5400, ArgentinaAbstract:Floral provincialism within the Southern Hemisphere during the Late Triassic (230?Ma) is characterized by the Ipswich and Onslow provinces, recognized originally in eastern Gondwana. However, new palynological assemblages from the Ischigualasto Formation, northwestern Argentina (231–225?Ma), change the phytogeographic interpretation for the Carnian–Norian in the westernmost Gondwana, which was previously considered part of the southern floral Ipswich province. Here we show the presence of diagnostic Euramerican species within assemblages dominated by Gondwanan taxa that allows us to refer the palynofloras to the Onslow province. Our new data extend the Onslow floral belt, previously recognized from the western edge of Tethys to Timor, to the western margin of South America. This has implications for palaeophytogeography, palaeoclimate reconstructions and the palaeoecology of a Triassic ecosystem, which has yielded significant vertebrate remains and is regarded important in the early evolution of groups such as the Dinosauria.

TESTING THE METAL OF LATE-TYPE KEPLER PLANET HOSTS WITH IRON-CLAD METHODS Authors:1. Andrew W. Mann (a) 2. Eric Gaidos (b) 3. Adam Kraus (c,d) 4. Eric J. Hilton (a)Affiliations:a. Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Dr, Honolulu, HI 96822, USAb. Department of Geology & Geophysics, University of Hawai'i, 1680 East-West Road, Honolulu, HI 96822, USAc. Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138, USAd. Clay Fellow Abstract:It has been shown that F, G, and early K dwarf hosts of Neptune-sized planets are not preferentially metal-rich. However, it is less clear whether the same holds for late K and M dwarf planet hosts. We report metallicities of Kepler targets and candidate transiting planet hosts with effective temperatures below 4500 K. We use new metallicity calibrations to determine [Fe/H] from visible and near-infrared spectra. We find that the metallicity distribution of late K and M dwarfs monitored by Kepler is consistent with that of the solar neighborhood. Further, we show that hosts of Earth- to Neptune-sized planets have metallicities consistent with those lacking detected planets and rule out a previously claimed 0.2 dex offset between the two distributions at 6? confidence. We also demonstrate that the metallicities of late K and M dwarfs hosting multiple detected planets are consistent with those lacking detected planets. Our results indicate that multiple terrestrial and Neptune-sized planets can form around late K and M dwarfs with metallicities as low as 0.25 solar. The presence of Neptune-sized planets orbiting such low-metallicity M dwarfs suggests that accreting planets collect most or all of the solids from the disk and that the potential cores of giant planets can readily form around M dwarfs. The paucity of giant planets around M dwarfs compared to solar-type stars must be due to relatively rapid disk evaporation or a slower rate of planet accretion, rather than insufficient solids to form a core.

Saturn's moon Titan might be in for some wild weather as it heads into its spring and summer, if two new models are correct. Scientists think that as the seasons change in Titan's northern hemisphere, waves could ripple across the moon's hydrocarbon seas, and hurricanes could begin to swirl over these areas, too. The model predicting waves tries to explain data from the moon obtained so far by NASA's Cassini spacecraft. Both models help mission team members plan when and where to look for unusual atmospheric disturbances as Titan summer approaches."If you think being a weather forecaster on Earth is difficult, it can be even more challenging at Titan," said Scott Edgington, Cassini's deputy project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We know there are weather processes similar to Earth's at work on this strange world, but differences arise due to the presence of unfamiliar liquids like methane. We can't wait for Cassini to tell us whether our forecasts are right as it continues its tour through Titan spring into the start of northern summer."Titan's north polar region, which is bejeweled with sprawling hydrocarbon seas and lakes, was dark when Cassini first arrived at the Saturn system in 2004. But sunlight has been creeping up Titan's northern hemisphere since August 2009, when the sun's light crossed the equatorial plane at equinox. Titan's seasons take about seven Earth years to change. By 2017, the end of Cassini's mission, Titan will be approaching northern solstice, the height of summer.Given the wind-sculpted dunes Cassini has seen on Titan, scientists were baffled about why they hadn't yet seen wind-driven waves on the lakes and seas. A team led by Alex Hayes, a member of Cassini's radar team who is based at Cornell University, Ithaca, N.Y., set out to look for how much wind would be required to generate waves. Their new model, just published in the journal Icarus, improves upon previous ones by simultaneously accounting for Titan's gravity; the viscosity and surface tension of the hydrocarbon liquid in the lakes; and the air-to-liquid density ratio."We now know that the wind speeds predicted during the times Cassini has observed Titan have been below the threshold necessary to generate waves," Hayes said. "What is exciting, however, is that the wind speeds predicted during northern spring and summer approach those necessary to generate wind waves in liquid ethane and/or methane. It may soon be possible to catch a wave in one of the solar system's most exotic locations."The new model found that winds of 1 to 2 mph (2 to 3 kilometers per hour) are needed to generate waves on Titan lakes, a speed that has not yet been reached during Titan's currently calm period. But as Titan's northern hemisphere approaches spring and summer, other models predict the winds may increase to 2 mph (3 kilometers per hour) or faster. Depending on the composition of the lakes, winds of that speed could be enough to produce waves 0.5 foot (0.15 meter) high.The other model about hurricanes, recently published in Icarus, predicts that the warming of the northern hemisphere could also bring hurricanes, also known as tropical cyclones. Tropical cyclones on Earth gain their energy from the build-up of heat from seawater evaporation and miniature versions have been seen over big lakes such as Lake Huron. The new modeling work, led by Tetsuya Tokano of the University of Cologne, Germany, shows that the same processes could be at work on Titan as well, except that it is methane rather than water that evaporates from the seas. The most likely season for these hurricanes would be Titan's northern summer solstice, when the sea surface gets warmer and the flow of the air near the surface becomes more turbulent. The humid air would swirl in a counterclockwise direction over the surface of one of the northern seas and increase the surface wind over the seas to possibly 45 mph (about 70 kilometers per hour)."For these hurricanes