Fossils

Dinosaur Fossils Predict Body Temperatures

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Shanidar Protein

Max Planck Society - Press Release: "An international team, led by researchers at the Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, in Leipzig, Germany, have extracted and sequenced protein from a Neanderthal from Shanidar Cave, Iraq dating to approximately 75,000 years old. It is rare to recover protein of this age, and remarkable to be able to determine the constituent amino acid sequence. This is the oldest fossil protein ever sequenced. Protein sequences may be used in a similar way to DNA, to provide information on the genetic relationships between extinct and living species. As ancient DNA rarely survives, this new method opens up the possibility of determining these relationships in much older fossils which no longer contain DNA (PNAS Online Early Edition, March 8, 2005)."

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New Study Shows Animal Family Tree Looking Bushy In Places

New Study Shows Animal Family Tree Looking Bushy In Places: "Writing this week (Dec. 23, 2005) in the journal Science, a team of UW-Madison scientists led by Antonis Rokas, now of the Broad Institute of MIT and Harvard, suggests that a branch-by-branch account of animal relationships over a vast expanse of time is difficult to reconstruct because early animal evolution occurred in bunches."

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Science's Breakthrough Of The Year: Watching Evolution In Action

Science's Breakthrough Of The Year: Watching Evolution In Action: "In 2005, scientists piled up new insights about evolution at the genetic level and the birth of species, including information that could help us lead healthier lives in the future. Ironically, these often-startling discoveries occurred in a year when backers of 'intelligent design' and other opponents of evolution sought to renew challenges to this fundamental concept."

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Scientists Narrow The Time Limits For The Human And Chimpanzee Split

Scientists Narrow The Time Limits For The Human And Chimpanzee Split: "The scientists estimated the time of divergence between species by studying the sequential arrangement of nucleotides that make up the chain-like DNA molecules of each species. The number of mutations in the DNA sequence of a species, compared with other species, is a gauge of its rate of evolutionary change. By calibrating this rate with the known time of divergence of a species on another branch of the tree-like diagram that shows relationships among species, scientists can estimate the time when the species they are studying evolved. In this case, the calibration time the scientists used was the split of Old World monkeys -- including baboons, macaques, and others -- from the branch of the phylogenetic tree that led to humans and apes, which fossil studies have shown is at least 24 million years ago. Using this calibration time, the team estimated that the human-chimp divergence occurred at least 5 million years ago, proportionally about one-fifth of the calibration time."

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Scientists Sequence DNA Of Woolly Mammoth

Scientists Sequence DNA Of Woolly Mammoth: "A team of genome researchers at Penn State University and experts in ancient DNA at McMaster University in Canada has obtained the first genomic sequences from a woolly mammoth, a mammal that roamed grassy plains of the Northern Hemisphere until it became extinct about 10,000 years ago. The team's research on bones preserved in Siberian permafrost will be published on 22 December 2005 by the journal Science on the Science Express website. The project also involved paleontologists from the American Museum of Natural History (USA) and researchers from Russia, the United Kingdom, France, and Germany."

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Geologists Link the "Great Dying" to Volcanism

Science & Technology at Scientific American.com: Geologists Link the "Great Dying" to Volcanism: Modified:
"Life on Earth almost died out about 252 million years ago. Roughly 90% of marine life and 70% of terrestrial life died out. At roughly the same time, a vast up swelling of magma on land that became Siberia covered between one million and four million cubic kilometers. Eruption continued for about a million years, with basaltic lava and poisonous gases emerging through cracks in Siberia's mantle. Rocks from Italy may have linked the extinctions with the massive upwellings of magma.

In a paper in the Dec '05 issue of Geology, Mark Sephton of Imperial College London and his colleagues reveal that sedimentary rocks from that period, formed on the bottom of a shallow sea, contain unusually elevated levels of organic material from soil and plants. Typically microbes break down suchmaterial immediately. However, these rocks suggest, that a great flood of such terrestrial organic matter reached the sea, swamping it and suffocating marine life. "Similar to the 'dead zone' nowadays spreading in the Gulf of Mexico, the soil crisis could have caused a worldwide expanse of uninhabitable low-oxygen conditions in shallow waters," explains team member Henk Visscher of Utrecht University in the Netherlands.

The researchers argue that deadly gases emitted during the Siberian eruption killed vegetation across the globe. Without roots to hold the soil in place, rivers and streams would have carried most of the dead vegetation to the sea where it then blocked the sun's light and consumed all the oxygen. "What began on land ended in the sea," Visscher says. "It seems there was no place to hide at this time of great dying."

Although this postulated linkage may not end the debate over what caused the earth's greatest mass extinction, it stands to shed light on the loss of life the planet is currently experiencing. "Land degradation is a worsening global problem thanks to human activity and soil erosion [that] has caused the loss of a third of arable land over the last 40 years," Sephton notes. "Identifying the nature of the end of Permian soil crisis may help us understand what is in store for us in the years ahead.""

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Acanthostega

Science & Technology at Scientific American.com: Getting a Leg Up on Land -- [ EVOLUTION ] -- Recent fossil discoveries cast light on the evolution of four-limbed animals from fish: "Among the first fossil finds to pave the way for our modern conception of tetrapod origins were those of a creature called Acanthostega, which lived about 360 million years ago in what is now eastern Greenland. It was first identified in 1952 by Erik Jarvik of the Swedish Museum of Natural History in Stockholm on the basis of two partial skull roofs. But not until 1987 did my colleagues and I finally find specimens revealing the postcranial skeleton of Acanthostega. "

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EVOLUTION: ON PHYLOGENETIC TREES

EVOLUTION: ON PHYLOGENETIC TREES: "Phylogenetic trees show historical relationships, not similarities. Although closely related species tend to be similar to one another, this is not necessarily the case if the rate of evolution is not uniform: Crocodiles are more closely related to birds than they are to lizards, even though crocodiles are indisputably more similar in external appearance to lizards."

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