科學(xué)60秒:透過鴕鳥看恐龍

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Sometimes it seems there's only so much we can learn about dinosaurs. We can't know what their coloration looked like, we can't watch them ____1____. We can only extrapolate from their remains. But now scientists say we can ____2____ a hint of dinosaur movement - from ostriches.
The giant, flightless birds still have feathered forelimbs that scientists assumed were now solely used for display and temperature regulation. But researchers from Germany and Belgium carefully observed hand-raised ostriches, and modeled their movement in the surrounding air streams. They found that ____3____ being useless in movement, the leftover wings help ostriches break quickly, turn, and zig-zag. The scientists presented their findings at the Society for Experimental Biology's annual conference in Prague.
Ostriches are descendants of dinosaurs, and the researchers liken ostrich movements to those of bipedal dinosaurs. Paleontologists had previously thought that some dinos' small forelimbs had served to catch insects or rip flesh. But this new research shows dinosaurs may have used their forelimbs to help with quickness, stability and ____4____. Further study in this field could lead to more accurate ideas of what it once looked like when dinosaurs went ____5____ their prehistoric landscape.