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  • richardmitnick 12:41 pm on May 26, 2016 Permalink | Reply
    Tags: , Paleobiology, Tiny Vampires, ,   

    From UCSB: “Tiny Vampires” Women in Science (No, the women are not the vampires in question) 

    UC Santa Barbara Name bloc

    May 25, 2016
    Julie Cohen

    1
    Susannah Porter. Photo Credit: Sonia Fernandez

    Paleobiologist Susannah Porter finds evidence of predation in ancient microbial ecosystems dating back more than 740 million years.

    2
    The Chuar Group in the Grand Canyon was once an ancient seabed. Photo Credit: Carol Dehler

    Vampires are real, and they’ve been around for millions of years. At least, the amoebae variety has. So suggests new research from UC Santa Barbara paleobiologist Susannah Porter.

    Using a scanning electron microscope to examine minute fossils, Porter found perfectly circular drill holes that may have been formed by an ancient relation of Vampyrellidae amoebae. These single-celled creatures perforate the walls of their prey and reach inside to consume its cell contents. Porter’s findings* appear in the Proceedings of the Royal Society B.

    “To my knowledge these holes are the earliest direct evidence of predation on eukaryotes,” said Porter, an associate professor in UCSB’s Department of Earth Science. Eukaryotes are organisms whose cells contain a nucleus and other organelles such as mitochondria.

    “We have a great record of predation on animals going back 550 million years,” she continued, “starting with the very first mineralized shells, which show evidence of drillholes. We had nothing like that for early life — for the time before animals appear. These holes potentially provide a way of looking at predator-prey interactions in very deep time in ancient microbial ecosystems.”

    Porter examined fossils from the Chuar Group in the Grand Canyon — once an ancient seabed — that are between 782 and 742 million years old. The holes are about one micrometer (one thousandth of a millimeter) in diameter and occur in seven of the species she identified. The holes are not common in any single one species; in fact, they appear in not more than 10 percent of the specimens.

    “I also found evidence of specificity in hole sizes, so different species show different characteristic hole sizes, which is consistent with what we know about modern vampire amoebae and their food preferences,” Porter said. “Different species of amoebae make differently sized holes. The Vampyrellid amoebae make a great modern analog, but because vampirelike feeding behavior is known in a number of different unrelated amoebae, it makes it difficult to pin down exactly who the predator was.”

    According to Porter, this evidence may help to address the question of whether predation was one of the driving factors in the diversification of eukaryotes that took place about 800 million years ago.

    “If that is true, then if we look at older fossil assemblages — say 1 to 1.6 billion years old — the fossilized eukaryote will show no evidence of predation,” Porter said. “I’m interested in finding out when drilling first appears in the fossil record and whether its intensity changes through time.”

    Porter also is interested in seeing whether oxygen played a role in predation levels through time. She noted that the microfossils those organisms attacked were probably phytoplankton living in oxygenated surface waters, but like vampyrellid amoebae today, the predators may have lived in the sediments. She suggests that those phytoplankton made tough-walled cysts — resting structures now preserved as fossils — that sank to the bottom where they were attacked by the amoebae.

    “We have evidence that the bottom waters in the Chuar Group in that Grand Canyon basin were relatively deep — 200 meters deep at most — and sometimes became anoxic, meaning they lacked oxygen,” Porter explained.

    “I’m interested to know whether the predators only were present and making these drill holes when the bottom waters contained oxygen,” Porter added. “That might tie the diversification of eukaryotes and the appearance of predators to evidence for increasing oxygen levels around 800 million years ago.

    “We know from the modern vampire amoebae that at least some of them make resting cysts themselves,” Porter said. “A former student of mine joked we should call these coffins. So one of our motivations is to see if we can find these coffins in the fossil assemblage as well. That’s the next project.”

    *Science paper:
    Tiny vampires in ancient seas: evidence for predation via perforation in fossils from the 780–740 million-year-old Chuar Group, Grand Canyon, USA

    See the full article here .

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    The University of California, Santa Barbara (commonly referred to as UC Santa Barbara or UCSB) is a public research university and one of the 10 general campuses of the University of California system. Founded in 1891 as an independent teachers’ college, UCSB joined the University of California system in 1944 and is the third-oldest general-education campus in the system. The university is a comprehensive doctoral university and is organized into five colleges offering 87 undergraduate degrees and 55 graduate degrees. In 2012, UCSB was ranked 41st among “National Universities” and 10th among public universities by U.S. News & World Report. UCSB houses twelve national research centers, including the renowned Kavli Institute for Theoretical Physics.

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  • richardmitnick 12:17 pm on February 17, 2015 Permalink | Reply
    Tags: , , , Paleobiology,   

    From U Washington: “Ancient rocks show life could have flourished on Earth 3.2 billion years ago” 

    U Washington

    University of Washington

    February 16, 2015
    Hannah Hickey

    1
    The oldest samples are sedimentary rocks that formed 3.2 billion years ago in
    northwestern Australia. They contain chemical evidence for nitrogen fixation by microbes. (R. Buick / UW)

    A spark from a lightning bolt, interstellar dust, or a subsea volcano could have triggered the very first life on Earth.

    But what happened next? Life can exist without oxygen, but without plentiful nitrogen to build genes – essential to viruses, bacteria and all other organisms – life on the early Earth would have been scarce.

    The ability to use atmospheric nitrogen to support more widespread life was thought to have appeared roughly 2 billion years ago. Now research from the University of Washington looking at some of the planet’s oldest rocks finds evidence that 3.2 billion years ago, life was already pulling nitrogen out of the air and converting it into a form that could support larger communities.

    “People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn’t until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse,” said co-author Roger Buick, a UW professor of Earth and space sciences. “Our work shows that there was no nitrogen crisis on the early Earth, and therefore it could have supported a fairly large and diverse biosphere.”

    The results were published Feb. 16 in Nature.

    The authors analyzed 52 samples ranging in age from 2.75 to 3.2 billion years old, collected in South Africa and northwestern Australia. These are some of the oldest and best-preserved rocks on the planet. The rocks were formed from sediment deposited on continental margins, so are free of chemical irregularities that would occur near a subsea volcano. They also formed before the atmosphere gained oxygen, roughly 2.3 to 2.4 billion years ago, and so preserve chemical clues that have disappeared in modern rocks.

    Even the oldest samples, 3.2 billion years old – three-quarters of the way back to the birth of the planet – showed chemical evidence that life was pulling nitrogen out of the air. The ratio of heavier to lighter nitrogen atoms fits the pattern of nitrogen-fixing enzymes contained in single-celled organisms, and does not match any chemical reactions that occur in the absence of life.

    “Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating,” said lead author Eva Stüeken, who did the work as part of her UW doctoral research. “It suggests that these really complicated enzymes apparently formed really early, so maybe it’s not so difficult for these enzymes to evolve.”

    Genetic analysis of nitrogen-fixing enzymes have placed their origin at between 1.5 and 2.2 billion years ago.

    “This is hard evidence that pushes it back a further billion years,” Buick said.

    Fixing nitrogen means breaking a tenacious triple bond that holds nitrogen atoms in pairs in the atmosphere and joining a single nitrogen to a molecule that is easier for living things to use. The chemical signature of the rocks suggests that nitrogen was being broken by an enzyme based on molybdenum, the most common of the three types of nitrogen-fixing enzymes that exist now. Molybdenum is now abundant because oxygen reacts with rocks to wash it into the ocean, but its source on the ancient Earth – before the atmosphere contained oxygen to weather rocks – is more mysterious*.

    The authors hypothesize that this may be further evidence that some early life may have existed in single-celled layers on land, exhaling small amounts of oxygen that reacted with the rock to release molybdenum to the water.

    “We’ll never find any direct evidence of land scum one cell thick, but this might be giving us indirect evidence that the land was inhabited,” Buick said. “Microbes could have crawled out of the ocean and lived in a slime layer on the rocks on land, even before 3.2 billion years ago.”

    Future work will look at what else could have limited the growth of life on the early Earth. Stüeken has begun a UW postdoctoral position funded by NASA to look at trace metals such as zinc, copper and cobalt to see if one of them controlled the growth of ancient life.

    Other co-authors are Bradley Guy at the University of Johannesburg in South Africa, who provided some samples from gold mines, and UW graduate student Matthew Koehler. The research was funded by NASA, the UW’s Virtual Planetary Laboratory, the Geological Society of America and the Agouron Institute.

    See the full article here.

    [*Sorry, not mysterious at all. Everything here, especially metals, comes from the ash of supernovae.]

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  • richardmitnick 9:13 am on February 3, 2015 Permalink | Reply
    Tags: , Microorganisms, Paleobiology, ,   

    From UCLA: “Scientists discover organism that hasn’t evolved in more than 2 billion years” 

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    UCLA

    February 02, 2015
    Stuart Wolpert

    1
    A section of 1.8 billion-year-old fossil-bearing rock. The fossils (dark areas) are essentially identical to fossils 500 million years older and to modern microorganisms.
    UCLA Center for the Study of Evolution and the Origin of Life

    Research actually provides further support for Darwin, UCLA professor says

    An international team of scientists has discovered the greatest absence of evolution ever reported — a type of deep-sea microorganism that appears not to have evolved over more than 2 billion years. But the researchers say that the organisms’ lack of evolution actually supports Charles Darwin’s theory of evolution.

    The findings are published online today by the Proceedings of the National Academy of Sciences.

    The scientists examined sulfur bacteria, microorganisms that are too small to see with the unaided eye, that are 1.8 billion years old and were preserved in rocks from Western Australia’s coastal waters. Using cutting-edge technology, they found that the bacteria look the same as bacteria of the same region from 2.3 billion years ago — and that both sets of ancient bacteria are indistinguishable from modern sulfur bacteria found in mud off of the coast of Chile.

    “It seems astounding that life has not evolved for more than 2 billion years — nearly half the history of the Earth,” said J. William Schopf, a UCLA professor of earth, planetary and space sciences in the UCLA College who was the study’s lead author. “Given that evolution is a fact, this lack of evolution needs to be explained.”

    3
    Deep-sea microorganisms are unchanged over more than 2 billion years (UCLA Center for the Study of Evolution and the Origin of Life)

    Charles Darwin’s writings on evolution focused much more on species that had changed over time than on those that hadn’t. So how do scientists explain a species living for so long without evolving?

    2
    UCLA professor J. William Schopf pioneered the techniques used to analyze microscopic fossils preserved inside ancient rocks.(John Vande Wege/UCLA)

    “The rule of biology is not to evolve unless the physical or biological environment changes, which is consistent with Darwin,” said Schopf, who also is director of UCLA’s Center for the Study of Evolution and the Origin of Life. The environment in which these microorganisms live has remained essentially unchanged for 3 billion years, he said.

    “These microorganisms are well-adapted to their simple, very stable physical and biological environment,” he said. “If they were in an environment that did not change but they nevertheless evolved, that would have shown that our understanding of Darwinian evolution was seriously flawed.”

    Schopf said the findings therefore provide further scientific proof for Darwin’s work. “It fits perfectly with his ideas,” he said.

    The fossils Schopf analyzed date back to a substantial rise in Earth’s oxygen levels known as the Great Oxidation Event, which scientists believe occurred between 2.2 billion and 2.4 billion years ago. The event also produced a dramatic increase in sulfate and nitrate — the only nutrients the microorganisms would have needed to survive in their seawater mud environment — which the scientists say enabled the bacteria to thrive and multiply.

    Schopf used several techniques to analyze the fossils, including Raman spectroscopy — which enables scientists to look inside rocks to determine their composition and chemistry — and confocal laser scanning microscopy — which renders fossils in 3-D. He pioneered the use of both techniques for analyzing microscopic fossils preserved inside ancient rocks.

    Co-authors of the PNAS research were Anatoliy Kudryavtsev, a senior scientist at UCLA’s Center for the Study of Evolution and the Origin of Life, and scientists from the University of Wisconsin, NASA’s Jet Propulsion Laboratory, Australia’s University of New South Wales and Chile’s Universidad de Concepción.

    Schopf’s research is funded by the NASA Astrobiology Institute.

    See the full article here.

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  • richardmitnick 4:23 am on January 29, 2015 Permalink | Reply
    Tags: , , Paleobiology, ,   

    From U Alberta: “Long-necked ‘dragon’ discovered in China “ 

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    University of Alberta

    January 28, 2015
    Kristy Condon

    2
    Artist’s conception of Qijianglong, chased by two carnivorous dinosaurs in southern China 160 million years ago (Illustration: Lida Xing)

    University of Alberta paleontologists including PhD student Tetsuto Miyashita, former master’s student Lida Xing and professor Philip Currie have discovered a new species of a long-necked dinosaur from a skeleton found in China. The findings have been published in a new paper in the Journal of Vertebrate Paleontology.

    Qijianglong (pronounced “CHI-jyang-lon”) is about 15 metres long and lived about 160 million years ago in the Late Jurassic. The name means “dragon of Qijiang,” for its discovery near Qijiang City, close to Chongqing. The fossil site was found by construction workers in 2006, and the digging eventually hit a series of large neck vertebrae stretched out in the ground. Incredibly, the head of the dinosaur was still attached.

    “It is rare to find a head and neck of a long-necked dinosaur together because the head is so small and easily detached after the animal dies,” explains Miyashita.

    The new species belongs to a group of dinosaurs called mamenchisaurids, known for their extremely long necks sometimes measuring up to half the length of their bodies. Most sauropods, or long-necked dinosaurs, have necks only about one-third the length of their bodies.

    Unique among mamenchisaurids, Qijianglong had neck vertebrae that were filled with air, making their necks relatively lightweight despite their enormous size. Interlocking joints between the vertebrae also indicate a surprisingly stiff neck that was much more mobile bending vertically than sideways, similar to a construction crane.
    Dino101

    “Qijianglong is a cool animal. If you imagine a big animal that is half neck, you can see that evolution can do quite extraordinary things,” says Miyashita.

    Mamenchisaurids are only found in Asia, but the discovery of Qijianglong reveals that there could be as many differences among mamenchisaurids as there are between long-necked dinosaurs from different continents.

    “Qijianglong shows that long-necked dinosaurs diversified in unique ways in Asia during Jurassic times—something very special was going on in that continent,” says Miyashita. “Nowhere else we can find dinosaurs with longer necks than those in China. The new dinosaur tells us that these extreme species thrived in isolation from the rest of the world.”

    Miyashita believes that mamenchisaurids evolved into many different forms when other long-necked dinosaurs went extinct in Asia. “It is still a mystery why mamenchisaurids did not migrate to other continents,” he says. It is possible that the dinosaurs were once isolated as a result of a large barrier such as a sea, and lost in competition with invading species when the land connection was later restored.

    The Qijianglong skeleton is now housed in a local museum in Qijiang. “China is home to the ancient myths of dragons,” says Miyashita. “I wonder if the ancient Chinese stumbled upon a skeleton of a long-necked dinosaur like Qijianglong and pictured that mythical creature.” – See more at: http://uofa.ualberta.ca/news-and-events/newsarticles/2015/january/long-necked-dragon-discovered-in-china#sthash.ZCpknCAJ.dpuf

    See the full article here.

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  • richardmitnick 11:18 am on January 27, 2015 Permalink | Reply
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    From LLNL: “Lawrence Livermore research finds early Mesoamericans affected by climate change” 


    Lawrence Livermore National Laboratory

    Jan. 26, 2015

    Anne M Stark
    stark8@llnl.gov
    925-422-9799

    1
    Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants at its peak. Scientists believe climate change was part of the reason the city was eventually abandoned.

    Scientists have reconstructed the past climate for the region around Cantona, a large fortified city in highland Mexico, and found the population drastically declined in the past, at least in part because of climate change.

    The research appears in the online edition of the Proceedings of the National Academy of Sciences for the week of Jan. 26.

    Lawrence Livermore researcher Susan Zimmerman and colleagues analyzed pollen, stable isotopes and elemental concentrations, which serve as proxies of past climatic and environmental conditions, from lake sediments in the region and found evidence of a regional drought between 500 and 1150 AD*, about the time Cantona was abandoned.

    Using Lawrence Livermore’s Center for Accelerator Mass Spectrometry, the team — consisting of the University of California, Berkeley; Universidad Nacional Autonóma de Mexico; and the GFZ German Research Center for Geosciences — dated terrestrial organic material from 12-meter-long sediment cores from the lake to establish the age control for this study. Radiocarbon dating and an age model showed that the centennial-scale arid interval between 500 and 1150 was overlaid on a long-term drying trend. The cores cover the last 6,200 years; however, the team focused on the last 3,800 years.

    2

    Cantona is now an archaeological site in Mexico, on the border with Veracruz, about an hour’s drive from the city of Puebla. Limited archaeological work has been done at the site, and only about 10 percent of the site can be seen. It was a prominent, if isolated, Mesoamerican city between 600 and 1000 AD. It was abandoned after 1050 AD.

    “We found that Cantona’s population grew in the initial phases of the drought, but by 1050 AD long-term environmental stress (the drought) contributed to the city’s abandonment,” Zimmerman and colleagues said. “Our research highlights the interplay of environmental and political factors in past human responses to climate change.”

    Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants. It is in a semiarid basin east of Mexico City.

    The team conducted a subcentennial reconstruction of regional climate by taking sediment samples from a nearby crater lake, Aljojuca. The modern climate of the region suggests that proxy data from the sediments record changes in summer monsoonal (May through October) precipitation.

    “Our results suggest that climate change played a contributing role in the site’s history,” Zimmerman said.

    *LLNL has been apprised of the fact that the use of “AD” and “BC” as terms for dating is now out of use, AD replaced by CE, BC replaced by BCE

    See the full article here.

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  • richardmitnick 5:23 am on January 20, 2015 Permalink | Reply
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    From Yale: “Fossil ankles indicate Earth’s earliest primates lived in trees” 

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    Yale University

    1
    (Illustration by Patrick Lynch)

    Earth’s earliest primates have taken a step up in the world, now that researchers have gotten a good look at their ankles.

    A new study has found that Purgatorius, a small mammal that lived on a diet of fruit and insects, was a tree dweller. Paleontologists made the discovery by analyzing 65-million-year-old ankle bones collected from sites in northeastern Montana.

    Purgatorius, part of an extinct group of primates called plesiadapiforms, first appears in the fossil record shortly after the extinction of non-avian dinosaurs. Some researchers have speculated over the years that primitive plesiadapiforms were terrestrial, and that primates moved into the tree canopy later. These ideas can still be found in some textbooks today.

    “The textbook that I am currently using in my biological anthropology courses still has an illustration of Purgatorius walking on the ground. Hopefully this study will change what students are learning about earliest primate evolution and will place Purgatorius in the trees where it rightfully belongs,” said Stephen Chester, the paper’s lead author. Chester, who conducted much of the research while at Yale University studying for his Ph.D., is an assistant professor at Brooklyn College, City University of New York. Chester is also a curatorial affiliate at the Yale Peabody Museum of Natural History.

    Until now, paleontologists had only the animal’s teeth and jaws to examine, which left much of its appearance and behavior a mystery. The identification of Purgatorius ankle bones, found in the same area as the teeth, gave researchers a better sense of how it lived.

    “The ankle bones have diagnostic features for mobility that are only present in those of primates and their close relatives today,” Chester said. “These unique features would have allowed an animal such as Purgatorius to rotate and adjust its feet accordingly to grab branches while moving through trees. In contrast, ground-dwelling mammals lack these features and are better suited for propelling themselves forward in a more restricted, fore-and-aft motion.”

    The research provides the oldest fossil evidence to date that arboreality played a key role in primate evolution. In essence, said the researchers, it implies that the divergence of primates from other mammals was not a dramatic event. Rather, primates developed subtle changes that made for easier navigation and better access to food in the trees.

    The research appears in the Jan. 19 online edition of the Proceedings of the National Academy of Sciences.

    The paper’s co-authors are Jonathan Bloch of the Florida Museum of Natural History at the University of Florida, who also contributed to the research as an Edward P. Bass Distinguished Visiting Environmental Scholar in the Yale Institute for Biospheric Studies; Doug Boyer of Duke University; and William Clemens of the University of California Museum of Paleontology, who collected fossils of Purgatorius and geological data over the past four decades with members of his field crews in Montana.

    See the full article here.

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  • richardmitnick 8:55 am on January 16, 2015 Permalink | Reply
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    From U Washington: “Tiny plant fossils a window into Earth’s landscape millions of years ago” 

    U Washington

    University of Washington

    January 15, 2015
    Michelle Ma

    Minuscule, fossilized pieces of plants could tell a detailed story of what the Earth looked like 50 million years ago.

    1
    A 49 million-year-old phytolith. Its curvy, large shape indicate the plant it came from grew in shady conditions. Scale bar is 10 micrometers.Regan Dunn, U of Wash.

    An international team led by the University of Washington has discovered a way to determine the tree cover and density of trees, shrubs and bushes in locations over time based on clues in the cells of plant fossils preserved in rocks and soil. Tree density directly affects precipitation, erosion, animal behavior and a host of other factors in the natural world. Quantifying vegetation structure throughout time could shed light on how the Earth’s ecosystems changed over millions of years.

    “Knowing an area’s vegetation structure and the arrangement of leaves on the Earth’s surface is key for understanding the terrestrial ecosystem. It’s the context in which all land-based organisms live, but we didn’t have a way to measure it until now,” said lead author Regan Dunn, a paleontologist at the UW’s Burke Museum of Natural History and Culture. Dunn completed this work as a UW doctoral student in the lab of Caroline Strömberg, the Estella B. Leopold associate professor in biology and curator of paleobotany at the Burke Museum.

    The findings are published Jan. 16 in the journal Science.

    The team focused its fieldwork on several sites in Patagonia, Argentina, which have some of the best-preserved fossils in the world and together represent 38 million years of ecosystem history (49-11 million years ago). Paleontologists have for years painstakingly collected fossils from these sites, and worked to precisely determine their ages using radiometric dating. The new study builds on this growing body of knowledge.

    2
    The researchers work in Miocene-aged deposits near Rio Chico in Chubut Province, Argentina.Regan Dunn, U of Wash.

    In Patagonia and other places, scientists have some idea based on ancient plant remains such as fossilized pollen and leaves what species of plants were alive at given periods in Earth’s history. For example, the team’s previous work documented vegetation composition for this area of Patagonia. But there hasn’t been a way to precisely quantify vegetation openness, aside from general speculations of open or bare habitats, as opposed to closed or tree-covered habitats.

    “Now we have a tool to go and look at a lot of different important intervals in our history where we don’t know what happened to the structure of vegetation,” said Dunn, citing the period just after the mass extinction that killed off the dinosaurs.

    “The significance of this work cannot be understated,” said co-author Strömberg. “Vegetation structure links all aspects of modern ecosystems, from soil moisture to primary productivity to global climate. Using this method, we can finally quantify in detail how Earth’s plant and animal communities have responded to climate change over millions of years, which is vital for forecasting how ecosystems will change under predicted future climate scenarios.”

    3
    Fossil phytoliths from a 40 million-year-old soil from the Sarmiento Formation, Gran Barranca, Chubut, Argentina. At the center is an epidermal phytolith indicative of open habitats by its smaller, less curvy shape. Scale bar is 10 micrometers.Regan Dunn, U of Wash.

    Work by other scientists has shown that the cells found in a plant’s outermost layer, called the epidermis, change in size and shape depending on how much sun the plant is exposed to while its leaves develop. For example, the cells of a leaf that grow in deeper shade will be larger and curvier than the cells of leaves that develop in less covered areas.

    Dunn and collaborators found that these cell patterns, indicating growth in shade or sun, similarly show up in some plant fossils. When a plant’s leaves fall to the ground and decompose, tiny silica particles inside the plants called phytoliths remain as part of the soil layer. The phytoliths were found to perfectly mimic the cell shapes and sizes that indicate whether or not the plant grew in a shady or open area.

    The researchers decided to check their hypothesis that fossilized cells could tell a more complete story of vegetation structure by testing it in a modern setting: Costa Rica.

    4
    Regan Dunn samples for phytoliths from the soil under a dense forest at Rincon de la Vieja National Park, Costa Rica.Melanie Conner, copyright Melanie Conner Photography

    Dunn took soil samples from sites in Costa Rica that varied from covered rainforests to grassy savannahs to woody shrub lands. She also took photos looking directly up at the tree canopy (or lack thereof) at each site, noting the total vegetation coverage.

    5
    This hemispherical photograph shows the tree canopy cover at a site in Santa Rosa National Park, Costa Rica. The corresponding forest profile (modified from Holdridge et al., 1971) gives a side profile of the forest’s density.Regan Dunn, U of Wash.

    Back in the lab, she extracted the phytoliths from each soil sample and measured them under the microscope. When compared with tree coverage estimated from the corresponding photos, Dunn and co-authors found that the curves and sizes of the cells directly related to the amount of shade in their environments. The researchers characterized the amount of shade as “leaf area index,” which is a standard way of measuring vegetation over a specific area.

    Testing this relationship between leaf area index and plant cell structures in modern environments allowed the team to develop an equation that can be used to predict vegetation openness at any time in the past, provided there are preserved plant fossils.

    “Leaf area index is a well-known variable for ecologists, climate scientists and modelers, but no one’s ever been able to imagine how you could reconstruct tree coverage in the past — and now we can,” said co-author Richard Madden of the University of Chicago. “We should be able to reconstruct leaf area index by using all kinds of fossil plant preservation, not just phytoliths. Once that is demonstrated, then the places in the world where we can reconstruct this will increase.”

    When Dunn and co-authors applied their method to 40-million-year-old phytoliths from Patagonia, they found something surprising — habitats lost dense tree cover and opened up much earlier than previously thought based on other paleobotanic studies. This is significant because the decline in vegetation cover occurred during the same period as cooling ocean temperatures and the evolution of animals with the type of teeth that feed in open, dusty habitats.

    The research team plans to test the relationship between vegetation coverage and plant cell structure in other regions around the world. They also hope to find other types of plant fossils that hold the same information at the cellular level as do phytoliths.

    Other co-authors are Matthew Kohn of Boise State University and Alfredo Carlini of Universidad Nacional de La Plata in Argentina.

    The research was funded by the National Science Foundation, the Geological Society of America, UW Biology and the Burke Museum.

    ###

    For more information, contact Dunn at dunnr@uw.edu or 206-685-0374.

    See the full article here.

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    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.

    So what defines us — the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

     
  • richardmitnick 12:10 pm on January 14, 2015 Permalink | Reply
    Tags: , , Paleobiology,   

    From livescience: “Ancient Scorpion Had Feet, May Have Walked Out of Ocean” 

    Livescience

    January 14, 2015
    Stephanie Pappas

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    A specimen of the new scorpion species Eramoscorpius brucensis, which lived about 430 million years ago, making it among the earliest scorpions. The species probably lived in water, but it had feet that would have allowed it to scuttle about on land. Credit: © David Rudkin, Royal Ontario Museum

    A new scorpion species found fossilized in the rocks of a backyard could turn the scientific understanding of these stinging creatures on its head.

    The fossils suggest that ancient scorpions crawled out of the seas and onto land earlier than thought, according to the researchers who analyzed them. In fact, some of the oldest scorpions had the equipment needed to walk out of their watery habitats and onto land, the researchers said. The fossils date back some 430 million to 433 million years, which makes them only slightly younger than the oldest known scorpions, which lived between 433 million and 438 million years ago.

    The new species “is really important, because the combination of its features don’t appear in any other known scorpion,” said study leader Janet Waddington, an assistant curator of paleontology at the Royal Ontario Museum in Toronto.

    The new species fell into Waddington’s hands almost by happenstance. Museum curators frequently get calls about fossils, most of which are run-of-the-mill, she told Live Science. But a woman who called about an “insect” in her backyard stone wall had something very exciting on her hands.

    “When she showed me this fossil, I just about fell on the floor, it was so amazing,” Waddington said.

    The fossil was no insect, but rather a scorpion — and a new species at that. Over the years, more specimens trickled in, mostly from patio stones and rock quarries, and one from a mislabeled fossil at a national park on Canada’s Bruce Peninsula. Now, Waddington and her team have 11 examples of the new species, ranging in length from 1.1 inches (29 millimeters) to 6.5 inches (165 millimeters).

    What made the animal, dubbed Eramoscorpius brucensis, so fascinating was its legs.

    Walking in water

    Previously, the earliest scorpion fossils found came from rocks that were originally deposited in the water, leading paleontologists to believe that the animals evolved on the seafloor, like crabs, and only later became landlubbers. Ancient scorpions had legs like crabs, with a tarsus, or foot segment, that was longer than the segment preceding it. This arrangement, Waddington said, would have meant the creatures walked on their “tippy-toes,” such as crabs do today.

    But E. brucensis was different. This species had a tarsus segment that was shorter than the segment before it, which would have made it possible for the animal to set its tarsus flat against the ground. In other words, this scorpion had feet.

    “They could have walked on their feet, which is really important because it meant that they could have supported their own weight,” Waddington said. Without the need for water to buoy them up, the animals could have walked on land.
    The largest specimen of the new scorpion species

    The fossils also show that the scorpions’ legs were solidly attached at the body, without the exaggerated “hinge” seen in scorpions that would have needed water to stay upright. What’s weird, Waddington said, is that all the other features of these scorpions seem aquatic. They are found in marine rocks, and their digestive systems appear to require water (in today’s land scorpions, digestion begins outside of their bodies, a process that requires adaptations these ancient scorpions lack).

    Waddington said she and her team suspect that the fossils they’ve collected are not the bodies of dead scorpions at all. Instead, they may be molts, exoskeletons left behind as the scorpions grow. Scorpions are incredibly vulnerable during molting, Waddington said, and in deep water, ancient squidlike animals would have loved a helpless scorpion snack. The scorpions that could haul themselves out of the water onto the shore to escape predators would have had a survival advantage. The rocks that house the scorpion fossils often feature ripples that would have been created when wind blew thin films of water over land, suggesting a shoreline lagoon habitat.

    What that means is that the first adaptations that scorpions developed for life on land could have appeared much earlier than researchers thought.

    “Our guys are really, really old,” Waddington said. “They’re vying for the second-oldest [scorpions] known.”

    The researchers reported their findings today (Jan. 13) in the journal Biology Letters.

    See the full article here.

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  • richardmitnick 10:00 pm on January 2, 2015 Permalink | Reply
    Tags: , , Paleobiology, ,   

    From U Chicago: “Modern genetics confirm ancient relationship between fins and hands” 

    U Chicago bloc

    University of Chicago

    December 29, 2014
    John Easton

    Paleontologists have documented the evolutionary adaptations necessary for ancient lobe-finned fish to transform pectoral fins used underwater into strong, bony structures, such as those of Tiktaalik roseae. This enabled these emerging tetrapods, animals with limbs, to crawl in shallow water or on land. But evolutionary biologists have wondered why the modern structure called the autopod—comprising wrists and fingers or ankles and toes—has no obvious morphological counterpart in the fins of living fishes.

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    Tiktaalik

    In the Dec. 22, 2014, issue of the Proceedings of the National Academy of Sciences, researchers argue previous efforts to connect fin and fingers fell short because they focused on the wrong fish. Instead, they found the rudimentary genetic machinery for mammalian autopod assembly in a non-model fish, the spotted gar, whose genome was recently sequenced.

    “Fossils show that the wrist and digits clearly have an aquatic origin,” said Neil Shubin, the Robert R. Bensley Distinguished Service Professor of Organismal Biology and Anatomy and a leader of the team that discovered Tiktaalik in 2004. “But fins and limbs have different purposes. They have evolved in different directions since they diverged. We wanted to explore, and better understand, their connections by adding genetic and molecular data to what we already know from the fossil record.”

    Initial attempts to confirm the link based on shape comparisons of fin and limb bones were unsuccessful. The autopod differs from most fins. The wrist is composed of a series of small nodular bones, followed by longer thin bones that make up the digits. The bones of living fish fins look much different, with a set of longer bones ending in small circular bones called radials.

    The primary genes that shape the bones, known as the HoxD and HoxA clusters, also differ. The researchers first tested the ability of genetic “switches” that control HoxD and HoxA genes from teleosts—bony, ray-finned fish—to shape the limbs of developing transgenic mice. The fish control switches, however, did not trigger any activity in the autopod.

    Teleost fish—a vast group that includes almost all of the world’s important sport and commercial fish—are widely studied. But researchers began to realize they were not the ideal comparison for studies of how ancient genes were regulated. When they searched for wrist and digit-building genetic switches, they found “a lack of sequence conservation” in teleost species.

    They traced the problem to a radical change in the genetics of teleost fish. More than 300 million years ago, after the fish-like creatures that would become tetrapods split off from other bony fish, a common ancestor of the teleost lineage went through a whole-genome duplication—a phenomenon that has occurred multiple times in evolution.

    By doubling the entire genetic repertoire of teleost fish, this WGD provided them with enormous diversification potential. This may have helped teleosts to adapt, over time, to a variety of environments worldwide. In the process, “the genetic switches that control autopod-building genes were able to drift and shuffle, allowing them to change some of their function, as well as making them harder to identify in comparisons to other animals, such as mice,” said Andrew Gehrke, a graduate student in the Shubin Lab and lead author of the study.

    Not all bony fishes went through the whole genome duplication, however. The spotted gar, a primitive freshwater fish native to North America, split off from teleost fishes before the WGD.

    When the research team compared Hox gene switches from the spotted gar with tetrapods, they found “an unprecedented and previously undescribed level of deep conservation of the vertebrate autopod regulatory apparatus.” This suggests, they note, a high degree of similarity between “distal radials of bony fish and the autopod of tetrapods.”

    They tested this by inserting gar gene switches related to fin development into developing mice. This evoked patterns of activity that were “nearly indistinguishable,” the authors note, from those driven by the mouse genome.

    “Overall,” the researchers conclude, “our results provide regulatory support for an ancient origin of the ‘late’ phase of Hox expression that is responsible for building the autopod.”

    This study was supported by the Brinson Foundation, the National Science Foundation, the Brazilian National Council for Scientific and Technological Development grants, the National Institutes of Health, the Volkswagen Foundation in Germany, the Alexander von Humboldt-Foundation, the Spanish and Andalusian governments, and Proyecto de Excelencia.

    Additional authors include Mayuri Chandran and Tetsuya Nakamura from the University of Chicago; Igor Schneider from the Instituto de Ciencias Biologicas, Universida de Federal do Para, Belem, Brazil; Elisa de la Calle-Mustienes, Juan J. Tena, Carlos Gomez-Marin and José Luis Gómez-Skarmeta from the Centro Andaluz de Biología del Desarrollo, Sevilla, Spain; and Ingo Braasch and John H. Postlethwait from the Institute of Neuroscience, University of Oregon.

    See the full article here.

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    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 2:54 pm on December 13, 2014 Permalink | Reply
    Tags: , , , , Paleobiology,   

    From Nautilus: “A Holy Land for Religion and Science 

    Nautilus

    Nautilus

    December 4, 2014
    By Amy Maxmen Produced by Yvonne Bang
    Photo & Footage by Amy Maxmen

    On a recent reporting trip in Ethiopia, I was struck by how evolution and religion coexist peacefully in the nation. Every day on my walk to Ethiopia’s National Museum, which houses the ancient bones of ape-like human predecessors, I passed a throng of women praying outside of St. Georges Cathedral, across the street from the museum. I was moved because the scene stood in contrast to the United States, where grandstanding debates, like the one this year between Bill Nye the Science Guy and creationist Ken Ham, seem to be a regular occurrence. In the video (above), you can hear chants from the cathedral bellowing into the museum courtyard.

    A distinguishing feature of Ethiopia is that both religion and science are bred in its bone, and the union doesn’t seem to be a matter of either side compromising. A mosaic at the museum’s entrance pictures Lucy, our famous human-like ancestor from over 3 million years ago, and an Orthodox Christian cross. Soon the Ethiopian government will open The Human Origin Museum, devoted to our evolution.

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    Lucy

    Generally speaking, Ethiopians are devout Christians or Muslims, and they’re quick to note the holy and historical sites that occur throughout the nation. Both the Old and New Testaments name Ethiopia several times. It is said that the grandson of Noah (of Ark fame) moved to a city in the north of the country, Axum. Today, the Ark of the Covenant—which contains tablets inscribed with Moses’ Ten Commandments—is purportedly locked within Axum’s Ethiopian Orthodox Church. Another name for Ethiopia, Abyssinia, occurs in the Qur’an. It is said that the prophet Muhammad advised his disciples to escape persecution in Mecca by fleeing there, where the Christian ruler of Axum welcomed Muslims with open arms. Ethiopian Jews allegedly descended from one of the lost tribes of Israel. And Rastafarians regard Ethiopia as their homeland.

    Ethiopia is also a holy land to paleontologists and evolutionary biologists. In addition to Lucy, 10 other species of hominid (members of our tribe that date back 6 million years) have been discovered in the country. Many of them were found buried west of Axum, in an arid region called the Afar, which rests at the intersection of three enormous tectonic plates that float above the Earth’s molten core. An Ethiopian paleoanthropologist, Zeresenay Alemseged, told me that during celebrations, the leader of the Afar begins ceremonies with a religious prayer, and then welcomes everyone to the cradle of humankind.

    Alemseged grew up in a devout Christian household in Axum. In primary school, he learned about the descent of humans from apes. “People separate their faith from evolution here,” he explained. “It’s just like having two languages or two systems of counting.” Now that he lives in San Francisco, where he directs the anthropology department at the California Academy of Sciences, he’s pondered why a clash occurs in the U.S. To him it seems disingenuous to reject one or the other completely. Many religious people rely on science to provide them a cancer therapy, and many people of science utter a prayer if a loved one falls dangerously ill.

    In the U.S., human evolution stormed into the limelight in the 1920s during the Scopes Trial, in which John Scopes was charged with teaching evolution to his public high school class in Tennessee. Those in the plaintiff’s camp described evolution as a threat to conservative values, and soon after, the creationist movement aligned with people who took a conservative stance on a host of social and cultural issues.

    “More often than not, accepting or rejecting evolution has become a matter of identity,” said Salman Hameed, a professor of integrated science and the humanities at Hampshire College. “If you are a member of the new Christian right, you are often against human evolution, against abortion, against global warming.” In other countries—such as Ethiopia—evolution does not carry the same historical baggage.

    Because evolution is included in a package deal of beliefs in the U.S., conversations for or against it become quickly heated. “If I think that accepting human evolution means rejecting God, my gut reaction might be to reject evolution because rejecting my religion is grave,” Hameed said. Rather than engage in futile debates, Hameed would prefer discussions about why a person feels the way they do. “Otherwise, it just amounts to us-versus-them, to idiot-calling on either side,” he said. That’s a shame because ultimately we’re all united in the same obsession: the tale of our creation.

    See the full article here.

    Please help promote STEM in your local schools.

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
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