Canguru pré-histórico caminhava...
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Prehistoric kangaroo was a walker
Prehistoric kangaroo was a walker
An
ancient Australian kangaroo apparently walked a lot like people do
today: upright, and stepping one foot at a time. In a paper published
today in PLOS ONE, researchers compared the skeletons of 66 modern and 78 extinct kangaroos
from a variety of genera and species. Modern kangaroos move either
rapidly by hopping on their hind legs or by walking slowly using all
four legs and their tails (pentapedally). In contrast, one of the
extinct groups of kangaroos in the study—the sthenurines, which lived
100,000 years ago—lacked many of the locomotory features of their modern
counterparts, including a flexible backbone, a sturdy tail, and
forelimbs capable of supporting their body weight.
This suggests that for sthenurines, hopping and pentapedal walking would have been very difficult. Instead, sthenurines appear to have been anatomically suited to standing upright and placing weight on one foot at a time—an essential part of walking bipedally. An upright posture also explains the sthenurines’ forepaws, which appear better suited for browsing on high-growing plants. Previously, sthenurines were thought to be unusually big-boned compared with their modern-day relatives; the comparisons offered by this study, however, show that they are, in fact, normally proportioned. Instead, it is our modern-day large kangaroos that are oddly slender for their size—an adaptation that helps them reach speeds of up to 60 kilometers an hour.
This suggests that for sthenurines, hopping and pentapedal walking would have been very difficult. Instead, sthenurines appear to have been anatomically suited to standing upright and placing weight on one foot at a time—an essential part of walking bipedally. An upright posture also explains the sthenurines’ forepaws, which appear better suited for browsing on high-growing plants. Previously, sthenurines were thought to be unusually big-boned compared with their modern-day relatives; the comparisons offered by this study, however, show that they are, in fact, normally proportioned. Instead, it is our modern-day large kangaroos that are oddly slender for their size—an adaptation that helps them reach speeds of up to 60 kilometers an hour.
Posted in Plants & Animals
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