A field guide to mesozoic birds and other winged dinosaurs

enough information about their plumage. While some primitive coelurosaurians,
such as compsognathids and deinodontoids, had “feathers”, these
appear to consist entirely of filamentous and/or down feathers, not vaned
feathers. The plumage of ornithomimosaurs is also known to be downy, and
while adults appear to have had feathers with central quills on at least their
arms, the exact anatomy of these structures is currently unknown. Among
maniraptorans, one specimen each of alvarezsaurians and segnosaurians
preserve feathers, but both lack evidence that they were vaned (possibly due
only to poor quality preservation). One intriguing species known only from
feathers, Praeornis sharovi, had rachides (quills) with barbs, but lacked true
barbules, having only strange ridges of tissue lining the individual barbs
(possibly an evolutionary precursor to barbules), and so is the closest outlier
to the definition of “feather” used here. All of those species are excluded
from this book, though future discoveries may reveal that they had modern
feathers after all.
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