Geosciences posts
- March 18, 2010
- 03:54 PM
- 15 views
Unique Fossils Record the Dining Habits of Ancient Sharks
A photograph and line drawing (left side) of the fossil dolphin Astadelphis gastaldii. The crescent-shaped line in the line drawing represents the bite of a large shark, with the red portions representing damage done directly to the bone. From Bianucci et al, 2010.
Shark attacks are events of speed and violence. When they have locked on to a prey item sharks seem to come out of nowhere, and though they can be quite gentle with their jaws (as on occasions when they are unsure about whether ........ Read more »
CHRISTY C. VISAGGI and STEPHEN J. GODFREY. (2010) VARIATION IN COMPOSITION AND ABUNDANCE OF MIOCENE SHARK TEETH FROM CALVERT CLIFFS, MARYLAND. Journal of Verterbrate Paleontology, 30(1), 26-35. info:/
Godfrey, S., & Smith, J. (2010) Shark-bitten vertebrate coprolites from the Miocene of Maryland. Naturwissenschaften. DOI: 10.1007/s00114-010-0659-x
BIANUCCI, G., SORCE, B., STORAI, T., & LANDINI, W. (2010) Killing in the Pliocene: shark attack on a dolphin from Italy. Palaeontology, 53(2), 457-470. DOI: 10.1111/j.1475-4983.2010.00945.x
- March 17, 2010
- 05:13 PM
- 35 views
Quartz, Cretan handaxes and Paleolithic seafaring
by Julien Riel-Salvatore in A Very Remote Period Indeed
A couple of months ago, I posted on the recent discovery of quartz hand axes on Crete by Strasser and Runnels. That post spurred quite a bit of discussion, and I also provided some additional thoughts shortly thereafter, based on the colonization of Cyprus. Since then, we've learned that these implements will be described in detail in the June issues of the journal Hesperia, and some decent photographs of some of the implements in question were published, which provides some more convincing data........ Read more »
Broodbank, C. (2006) The Origins and Early Development of Mediterranean Maritime Activity. Journal of Mediterranean Archaeology, 19(2). DOI: 10.1558//jmea.2006.v19i2.199
- March 16, 2010
- 04:53 PM
- 31 views
Earth's forgotten youth - and beyond
by Chris Rowan in Highly Allochthonous
The further back in time we go, the more and more fragmented the Earth's geological record becomes. Whilst not exactly common, rocks with ages up to about 3.5 billion years old are found at multiple points on the Earth's surface. However, rocks older than this are much less common. Extensive outcrops older than about 3.8 billion years are exceptionally rare, possibly because a series of very large meteorite impacts prior to this time - the Late Heavy Bombardment - largely destroyed any older ........ Read more »
Goldblatt, C., Zahnle, K. J., Sleep, N. H., & Nisbet, E. G. (2010) The Eons of Chaos and Hades. Solid Earth, 1-3. info:/
- March 16, 2010
- 11:07 AM
- 21 views
Sea Change
by Roberta Kwok in Journal Watch Online
Iron fertilization could increase toxin production in ocean
... Read more »
Trick, C.G. et al. (2010) Iron enrichment stimulates toxic diatom production in high-nitrate, low-chlorophyll areas. Proceedings of the National Academy of Sciences. info:/10.1073/pnas.0910579107
- March 15, 2010
- 07:40 PM
- 22 views
Krill v. Salps in the Southern Ocean
by Sam in Oceanographer's Choice
Last week, writing about copepods, I mentioned that they make up what is probably the most massive group of animals on earth. I also mentioned the likely runner up: krill. In particular, the Antarctic krill, Euphausia superba.
The Euphausiids are a major group of small, shrimp-like crustaceans found worldwide in the marine plankton. [...]... Read more »
V Loeb, V Siegel, O Holm-Hansen, R Hewitt, W Fraser, W Trivelpiece, S Trivelpiece. (1997) Effects of sea-ice extent and krill or salp dominance on the Antarctic food web. Nature, 897-900. info:/
- March 15, 2010
- 01:04 PM
- 38 views
Dry Spell
by Roberta Kwok in Journal Watch Online
Study contradicts idea that drought caused Amazon 'greening'
... Read more »
Samanta, A. et al. (2010) Amazon forests did not green-up during the 2005 drought. Geophysical Research Letters, 37(5). DOI: 10.1029/2009GL042154
- March 13, 2010
- 12:29 PM
- 39 views
High Arctic soil carbon underestimated
by Phil Camill in Global Change: Intersection of Nature and Culture
Most people have heard about the potential positive feedback of soil carbon on climate: As temperatures warm, soil microbes are more active and permafrost begins to thaw–both of which can hasten decomposition and the release of CO2 to the atmosphere. This, in turn, has the potential to accelerate warming.
A lot of us who study climate [...]... Read more »
Burnham, J. H., and R. S. Sletten. (2010) Spatial Distribution of Soil Organic Carbon in Northwest Greenland and Underestimates of High Arctic Carbon Stores. Global Biogeochemical Cycles. info:/10.1029/2009GB003660
- March 13, 2010
- 09:35 AM
- 30 views
AMS Climate briefing rundown
by Callan Bentley in Mountain Beltway
Yesterday I attended a climate change briefing hosted by the American Meteorological Society (in conjunction with NSF, AGU, AAAS, and the American Statistical Association). It was in the Hart Senate Office Building, but I didn’t see any senators at the briefing.
It was an interesting format: 3 talented speakers giving 3 “fifteen-minute” presentations (really more like [...]... Read more »
Solomon, S., Plattner, G., Knutti, R., & Friedlingstein, P. (2009) Irreversible climate change due to carbon dioxide emissions. Proceedings of the National Academy of Sciences, 106(6), 1704-1709. DOI: 10.1073/pnas.0812721106
- March 12, 2010
- 10:01 PM
- 55 views
Move over cows! Methane outgassing in the Arctic Sea
Methane! Move over cow flatulence and burping, methane is leaking from under the Arctic in a big way. Methane, that innocuous-seeming molecule with 4 hydrogens and a carbon, is actually a more potent greenhouse gas than the carbon dioxide molecule of greater fame–up to 25 times more potent actually. However, atmospheric methane concentrations are much [...]... Read more »
Shakhova, N., Semiletov, I., Salyuk, A., Yusupov, V., Kosmach, D., & Gustafsson, O. (2010) Extensive Methane Venting to the Atmosphere from Sediments of the East Siberian Arctic Shelf. Science, 327(5970), 1246-1250. DOI: 10.1126/science.1182221
- March 12, 2010
- 11:22 AM
- 42 views
Your Friday Dose of Weird: Two new Cambrian critters
When it comes to aliens, Hollywood really does not have much imagination. Most extraterrestrials that have appeared on the big screen look very much like us, or are at least some kind of four-to-six-limbed vertebrate, and this says more about out own vanity than anything else. It would be far more interesting, I think, to take the weird and wonderful organisms of the Cambrian as inspiration for alien life forms, and two new critters have just been added to the odd Cambrian menagerie. Read the ........ Read more »
Caron, J., Conway Morris, S., & Shu, D. (2010) Tentaculate Fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) Interpreted as Primitive Deuterostomes. PLoS ONE, 5(3). DOI: 10.1371/journal.pone.0009586
STEIN, M. (2010) A new arthropod from the Early Cambrian of North Greenland, with a ‘great appendage’-like antennula. Zoological Journal of the Linnean Society, 158(3), 477-500. DOI: 10.1111/j.1096-3642.2009.00562.x
- March 12, 2010
- 10:30 AM
- 38 views
Incisivosaurus, a Dinosaur With an Overbite
by Brian Switek in Dinosaur Tracking
Over and over again the same dinosaurs show up in the news: Tyrannosaurus, Triceratops, Apatosaurus, Velociraptor, etc., etc., etc. Movies, books and television have made them into superstars, but we should not forget that these dinosaurs represent only a small part of the range of dinosaur diversity. There are many kinds of dinosaurs many people [...]... Read more »
Xu, X., Cheng, Y., Wang, X., & Chang, C. (2002) An unusual oviraptorosaurian dinosaur from China. Nature, 419(6904), 291-293. DOI: 10.1038/nature00966
- March 10, 2010
- 09:40 PM
- 38 views
Natural climate factors unlikely to put the brakes on greenhouse-gas-driven sea level rise this century
by Phil Camill in Global Change: Intersection of Nature and Culture
The IPCC 2007 report projected a conservative sea level rise of about 18-59 cm by the year 2100.
Why conservative? Because it mainly accounted for things we know are happening and can measure well—like thermal expansion of the ocean and melting of land glaciers (see here for a discussion of the Kilimanjaro example). What it doesn’t [...]... Read more »
Jevrejeva, S., J. C. Moore, and A. Grinsted. (2010) How will sea level respond to changes in natural and anthropogenic forcings by 2100?. Geophysical Research Letters. info:/10.1029/2010GL042947
- March 10, 2010
- 05:41 PM
- 44 views
Prehistoric DNA reveals the story of a Pleistocene survivor, the muskox
A muskox (Ovibos moschatus), photographed in Alaska. From Flickr user drurydrama.
Of all the mass extinctions that have occurred during earth's history, among the most hotly debated is the one which wiped out mammoths, saber-toothed cats, giant ground sloths, and the other peculiar members of the Pleistocene megafauna around 12,000 years ago. It was not the most severe mass extinction, not by a long shot, but unlike the end-Cretaceous catastrophe 65 million years ago there is no single "sm........ Read more »
Campos, P., Willerslev, E., Sher, A., Orlando, L., Axelsson, E., Tikhonov, A., Aaris-Sorensen, K., Greenwood, A., Kahlke, R., Kosintsev, P.... (2010) Ancient DNA analyses exclude humans as the driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.0907189107
- March 10, 2010
- 03:50 PM
- 40 views
Ancient DNA Isolated from Fossil Eggshells May Provide Clues to Eggstinction of Giant Birds
by GrrlScientist in Living the Scientific Life (Scientist, Interrupted)
tags: evolution, evolutionary biology, ancient DNA, aDNA, molecular biology, molecular ecology, archaeology, paleontology, fossil eggshell, extinct birds, giant moa, Dinornis robustus, elephant birds, Aepyornis maximus, Mullerornis, Thunderbirds, Genyornis, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper, journal club
Elephant bird, Aepyornis maximus, egg
compared to a human hand with a hummingbird egg balanced on a fingertip.
To conduct my avian research, I've isolated and........ Read more »
Charlotte L. Oskam, James Haile, Emma McLay, Paul Rigby, Morten E. Allentoft, Maia E. Olsen, Camilla Bengtsson, Gifford H. Miller, Jean-Luc Schwenninger, Chris Jacomb, Richard Walter, Alexander Baynes, Joe Dortch, Michael Parker-Pearson, M. Thomas P. Gilb. (2010) Fossil avian eggshell preserves ancient DNA. Proc. R. Soc. B. info:/10.1098/rspb.2009.2019
- March 10, 2010
- 12:50 PM
- 41 views
Spent Hydrogen Regeneration in Ammonia Borane Derivatives
by Michael Long in Phased
Shin-Yuan Liu (University of Oregon, United States) and coworkers have addressed a challenge that is often brushed aside in hydrogen fuel cell research, but which is absolutely critical for practical, real-world applications. This news feature was written on March 10, 2010.... Read more »
Campbell, P. G., Zakharov, L. N., Grant, D. J., Dixon, D. A., & Liu, S.-Y. (2010) Hydrogen Storage by Boron−Nitrogen Heterocycles: A Simple Route for Spent Fuel Regeneration. Journal of the American Chemical Society, 132(10), 3289-3291. DOI: 10.1021/ja9106622
- March 10, 2010
- 09:58 AM
- 49 views
Asteroid Strike Confirmed as Dinosaur Killer
by Brian Switek in Dinosaur Tracking
Sixty-five million years ago, life on Earth suffered one of the worst mass extinctions of all time. It was an event that killed creatures across the spectrum of life’s diversity, from tiny marine invertebrates to the largest dinosaurs, but what could have caused it?
A number of hypotheses have been forwarded over the years, most of [...]... Read more »
Schulte, P., Alegret, L., Arenillas, I., Arz, J., Barton, P., Bown, P., Bralower, T., Christeson, G., Claeys, P., Cockell, C.... (2010) The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary. Science, 327(5970), 1214-1218. DOI: 10.1126/science.1177265
- March 9, 2010
- 03:23 PM
- 44 views
Beyond Borders
by Roberta Kwok in Journal Watch Online
Rich countries import substantial carbon dioxide emissions
... Read more »
Davis, S.J., & K. Caldeira. (2010) Consumption-based accounting of CO2 emissions. Proceedings of the National Academy of Sciences. info:/10.1073/pnas.090674107
- March 9, 2010
- 02:35 PM
- 67 views
Evolutionary history of early primates places human origins in context
A simplified evolutionary tree of primate relationships showing the placement of Darwinius in relationship to other groups. From Williams et al., 2010.
The study of human origins can be a paradoxical thing. We know that we evolved from ancestral apes (and, in fact, are just one peculiar kind of ape), yet we are obsessed with the features that distinguish us from our close relatives. The "big questions" in evolutionary anthropology, from why we stand upright to how our brains became so larg........ Read more »
Williams, B., Kay, R., & Kirk, E. (2010) New perspectives on anthropoid origins. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.0908320107
- March 8, 2010
- 10:12 PM
- 50 views
The hidden global CO2 emissions of consumerism
by Phil Camill in Global Change: Intersection of Nature and Culture
It’s been easy for citizens of the developed, industrialized world to criticize China and India over their rapidly growing greenhouse gas emissions. This was one of the major reasons why the Kyoto Protocol was never ratified in the United States.
As many have pointed out, however, there are several flaws with this argument:
The per-capita C emissions [...]... Read more »
Steven J. Davis and Ken Caldeira. (2010) Consumption-based accounting of CO2 emissions . PNAS. info:/10.1073/pnas.0906974107
- March 8, 2010
- 08:35 AM
- 90 views
A Review of the Chicxulub impact extinction link
by CM in The Iapetus Beat
There's a new Science paper by Schulte and others espousing the link between the Chicxulub impact event and the mass extinction at the end of the Cretaceous (K), ~65.5 million years ago, and it has received significant media attention. The forty-one (!) pro-bolide scientists review the theory and evidence that has accumulated since the seminal Alvarez paper in 1980 which proposed a link between an extraterrestrial impact and the extinction and the Hildebrand et alia (1991) study which reporte........ Read more »
Alvarez, L., Alvarez, W., Asaro, F., & Michel, H. (1980) Extraterrestrial Cause for the Cretaceous-Tertiary Extinction. Science, 208(4448), 1095-1108. DOI: 10.1126/science.208.4448.1095
Bralower, T., Eccles, L., Kutz, J., Yancey, T., Schueth, J., Arthur, M., & Bice, D. (2010) Grain size of Cretaceous-Paleogene boundary sediments from Chicxulub to the open ocean: Implications for interpretation of the mass extinction event. Geology, 38(3), 199-202. DOI: 10.1130/G30513.1
Schulte, P., Alegret, L., Arenillas, I., Arz, J., Barton, P., Bown, P., Bralower, T., Christeson, G., Claeys, P., Cockell, C.... (2010) The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary. Science, 327(5970), 1214-1218. DOI: 10.1126/science.1177265
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