UNITED KINGDOM: 3-D scanning technique allows scientists to see how little a daddy long legs has changed over all their time time on earth

Record ID: 721407

  • Title: UNITED KINGDOM: 3-D scanning technique allows scientists to see how little a daddy long legs has changed over all their time time on earth
  • Date: 12th October 2011
  • Summary: LONDON, ENGLAND, UNITED KINGDOM (RECENT) (REUTERS) VARIOUS OF DADDY LONG LEGS
  • Embargoed: 27th October 2011 13:00
  • Keywords:
  • Location: United Kingdom, United Kingdom
  • Country: United Kingdom
  • Topics: Environment / Natural World,Technology
  • Reuters ID: LVA7Y5KN1L0QQJC7QFPRSDBYV1ZR
  • Story Text: The common daddy long legs appears frequently in British houses at this time of year, annoying and scaring housewives in equal measure.
    Harmless to humans, the daddy long legs, or harvestman, is famous for its small body and eight outsized legs which enable it to skitter up walls fast.
    Other than that, most people think the arachnid unremarkable and would probably be surprised to hear that it pre-dates the dinosaurs, living in forests in the Carboniferous period more than 300 million years ago.
    Now scientists from Imperial College London have made a major discovery which may change the way palaeontologists view the pre-historic creature. By studying fossils of two ancient types of harvestmen, they have revealed in new three-dimensional virtual fossil models that the arachnids have barely evolved in all their time on Earth.
    Most palaeontologists analyse fossils by splitting open a rock and looking at the creatures encased inside. This means that they can often only see part of a three-dimensional fossil and cannot explore all of the fossil's features.
    By contrast the team, led by Mark Sutton, senior lecturer at Imperial, used computed tomography to create 3D models of two fossilised species of harvestmen, from the Dyspnoi and Eupnoi suborders.
    Sutton explained his team's methodology.
    "If you imagine taking a complicated three-dimensional object, splitting it down the middle, and looking what you've got you don't really get a very good idea of what's going on. You just see one surface. But using modern CT scanning technology we can extract the entire fossil, get the whole thing out, move them into the virtual realm and produce these virtual fossils, virtual reconstructions are what we've got. "
    He continued: "It takes the fossil, you put it on a turntable and it shines X-rays through it to take a picture at the back like a normal X-ray and then it rotates it slightly and it does it again, it takes it again, and it does it again repeatedly for about three thousand different shots rotating very slowly for a full circle. That data that this produces, this series of rotational X-ray images using complicated computer algorhythms can be stitched into virtual slices of the specimen which show every level inside and we can take those slices and with more computer jiggery-pokery turn those into 3D models."
    The 3-D models were created using a CT scanner based at the Natural History Museum in London. In the study scientists took 3,142 x-rays of the fossils and compiled the images into accurate 3D models.
    The models, of the Dyspnoi and Eupnoi species, are providing fresh insights into how these ancient creatures survived in the Earth's ancient forests.
    "We can get so much anatomical detail out, we can see the curves of the end of the legs or the spines, the arrangements of all the details, that we can plug them into the modern analytical techniques that were used to work out how creatures are related to each other in the same way as we can with modern animals, they're almost as good," Sutton said.
    He added: "We've got so much data in that we can get a proper quantitative assessment of where they fit in the tree of life."
    Sutton said the findings showed how little the creatures had evolved.
    "These very early ones are surprisingly like modern ones. It's a group that hasn't really done very much. It's obviously found a way of living that works and has decided not to change it and that mode of life has been perfectly stable despite all the vast number of changes within the last 300 million years. The creatures today look much the same as they did then," he said.
    The researchers found clues as to how both creatures may have lived hundreds of millions of years ago. The team believe that the Eupnoi probably lived in foliage just above the forest floor, which may have helped it to hide from predators lurking on the ground. The 3D model of the Eupnoi revealed it had long legs with a curvature at the end similar to the legs of its modern relatives who use the curved leg parts to grip onto vegetation while moving from leaf to leaf.
    The researchers also determined that the Eupnoi's body had a thin and soft outer shell or exoskeleton by analysing a section of the 3D fossil showing a part of its abdomen that had been crushed during the fossilisation process.
    The Dyspnoi fossil had spikes on its back and the scientists believe this may have provided it with some protection from predators who would have found the creature a prickly meal to swallow. The creature may have lived in moist, woody debris on the forest floor. Dyspnoi's modern American descendent Acuclavella cosmetoides also has spikes for protection and lives in similar environmental conditions.
    Until now most people have thought harvestmen barely worthy of a second glance.
    But these 3D models are set to revolutionise their image, marking the daddy long legs as the unchanging, great grand-daddy of the arachnid world.
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