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China’s Feathered Dinosaurs
Caudipteryx tail with impressions
of fan of tail feathers.
CLOSE WINDOW
than are the downy feathers of Sinosauropteryx. As in Caudipteryx, a fan of feathers (retrices) may
—there is some uncertainty on this point—attach to the tail tip in the larger Sinosauropteryx. But the
smaller specimen has no fan of enlarged tail feathers. If the Sinosauropteryx specimens are adult and
juvenile of the same species, that could explain the difference, namely, that the larger specimen is sexually
mature and the smaller is not. That in turn suggests that the use of the tail in courtship, so distinctive of birds
today, arose long before birds did.
The form of the remiges (flight feathers) and retrices (tail feathers) in Caudipteryx suggests that they
possessed the tiny hooks that bind feather filaments into the aerodynamic structures common to flying
dinosaurs. It is nonetheless clear that Caudipteryx could not fly: its arms were far too short and its flight
feathers far too small to support its body weight. Moreover, flight feathers in flying dinosaurs have curved
shafts and asymmetrical vanes (the web or expanded flat part of the feather). But the “flight” feathers in
Caudipteryx are like those of non-flying birds, with straight shafts and symmetrical vanes.