Today we dissected an owl pellet to study the bones inside. Using a probe and forceps, we broke apart an owl pellet, separated the bones from the fur, categorized them, then tried to identify the organism that was in the pellet.
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| our owl pellet |
After studying the bones in our owl pellet, we concluded that the organism in our pellet was a shrew. We determined by comparing our bones with an identification chart. In particular, we used the skull, mandible, and tibia and fibula to determine that our organism was a shrew. Our organism's skull and mandible resembled the skull and mandible of the shrew in the diagram; furthermore, the skull was 14 mm long and the mandible was 10 mm long, the average lengths of a shrew's skull and mandible. Also, the fused-together tibia and fibula (bottom-right-most bone in the picture on the right below) resembled the tibia and fibula of the shrew in the identification chart.
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| some bones from the pellet |
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| bones sorted in a chart |
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Compared to a human skeleton, our shrew skeleton had the same basic parts: skull, vertebral column, ribs, and limbs. These bones all fit in pretty much the same way, and they all perform the same function a human's skeleton does. Some of the bones, like the skull, are made of several fused-together parts, just like a human's.
However, compared to a human skeleton, a shrew skeleton has many differences. For example, the skull and mandible of a shrew are shaped very differently from the skull and mandible of a human. Also, a shrew's pelvis is shaped very differently from a human's (it is longer), since a shrew crawls around on all four feet while a human walks upright. A shrew's tibia and fibula are fused together, where as a human's tibia and fibula are separate bones.
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