Articles: Fossil Find Is World's Oldest Insect

Discussion in 'Health and medical' started by Robert Karl Sto, Feb 17, 2004.

  1. Fossil Find Is World's Oldest Insect

    Scientists have identified the oldest known insect from its fossilized jaw remains. A report
    published today in the journal Nature describes the creature, which lived between 408 and 438
    million years ago. The results push back the earliest appearance of winged insects by nearly 80
    million years and suggest that the creatures were among the first animals to arrive on land.

    David A. Grimaldi of the American Museum of Natural History, who wrote the paper with Michael S.
    Engel of the University of Kansas, describes the find as "completely serendipitous." During the
    course of researching a book on insect evolution, he explains, they were initially focused on
    another sample stored in the vault of London's Natural History Museum. But the slide stored next to
    it-a sample of chert (see top image) from Rhynie, Scotland, initially studied in 1928-caught their
    interest, and they brought it back to the U.S. for further study. "I remember sticking it under my
    microscope," Grimaldi says, "and Michael and I kind of looked at each other and said, 'Holy moly, do
    you see what I see? These are actual true insect mandibles [jaw parts].'" Specifically, diagnostic
    features of the jaw's joint anatomy (see bottom image) indicate that the remains belonged to a
    winged insect, Rhyniognatha hirsti

    The oldest known evidence of winged insects-that is, complete fossilized bodies with fully formed
    wings attached--dates to around 330 million years ago. But because there is a diversity of species
    capable of powered flight from this time period, insects clearly evolved wings well before that
    time. "This chert provides a tantalizing scrap of evidence to suggest that we're missing a huge
    amount," Grimaldi remarks, "and there's probably this wonderful progression of insects with
    protowings yet to be discovered." --Sarah Graham

    >From Scientific American
    http://click.exacttarget.com/?fe8f1173736d017975-fe3016707360067c711779

    Cloned Human Embryos Yield Stem Cells

    Scientists in South Korea have succeeded in obtaining stem cells from cloned human embryos. A report
    published online today by the journal Science describes the work, in which 30 embryos of about 100
    cells were created and used to harvest stem cells that later differentiated into a variety of tissue
    types. The findings offer hope for treating disease through so-called therapeutic cloning but are
    sure to revive ethical debates.

    The list of successfully cloned animals includes sheep, mice, horses and cats, among others, but
    primates have proved difficult. In the new work, a team of researchers led by Woo Suk Hwang of Seoul
    National University collected 242 eggs from 16 unpaid volunteers who knew their eggs would be used
    for scientific experiments. The scientists transferred the nucleus of a somatic, or nonreproductive,
    cell into an egg from the same donor that had had its nucleus removed. The researchers used a
    slightly different technique to extract the contents of the egg-employing gentle extrusion instead
    of the more commonly used suction method-which, together with careful timing and the freshness of
    the donated eggs, may have aided their success.

    http://click.exacttarget.com/?fe881173736d017e7d-fe3016707360067c711779

    Posted by Robert Karl Stonjek.
     
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