Porcupine quills are hollow, like feathers, and are made from the same material, but then so are hairs, and fingernails, and claws and scales. The... Jan 08, 2015 — Porcupine quills are hollow, like ...
image: (A) View of right ulna of Velociraptor IGM 100/981. (B) Detail from cast of red box in (A), with arrows showing six evenly spaced feather quill knobs. (C) View of right ulna of a turkey vulture ...
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