Dictionary

hypoptilum en · NOUN

Etymology

From New Latin hypoptilum, from hypo- + Ancient Greek πτίλον (ptílon, “soft feathers, down”).

Meanings

1. (rare) An aftershaft.
   • This secondary feather is known as the aftershaft or hypoptilum, and its presence or absence constitutes the most important structural difference in the feathers of existing birds. 1924 October 30, W. DeW. Miller, “Variations in the structure of the aftershaft and their taxonomic value”, in American Museum Novitates, number 140:
   • The feathers in some ratites are unusual as they are less reduced than is the norm in birds—each feather has, in addition to the main feather, a large “after-shaft” or hypoptilum. 2016, Michael Heads, Biogeography and Evolution in New Zealand:

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