Actually, it's tomorrow's _Nature_, since it's a British journal. Anyway,
the latest issue of _Nature_ features this article, which will put a smile
on a few faces.
However, Prum (2002) mentioned that the specimen has barbules, and I see no
mention of barbules in the paper. If barbules are established to be present
(either by direct observation or inferred from the arrangement of the barbs)
then the rachis-and-barbed feathers of BPM 1 3-13 would qualify as
'bipinnate'. I would guess we'll have to wait for the complete description
for the resolution of that issue.