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Modern feathers on a non-avian dinosaur - today's Nature



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.  (I had advanced warning - thanks to the kind soul who gave
me the heads-up.)


MARK NORELL, QIANG JI, KEQIN GAO, CHONGXI YUAN, YIBIN ZHAO & LIXIA WANG
(2002).  Palaeontology: 'Modern' feathers on a non-avian dinosaur.  Nature
416: 36-37.


This is a 'Brief Communication' that (appropriately enough) briefly
describes a new theropod specimen, BPM 1 3-13, from the Jiufotang Formation
in Liaoning Province, China.  This is the specimen referred to by Prum
(2002) in his recent _Auk_ article.  The dromaeosaur (which is not assigned
to a specific genus or species by Norell et al.) comprises a nearly complete
skeleton measuring around 95cm long.  The tail is proportionately longer
than in NGMC 91 (which the authors say "can probably be referred to
_Sinornithosaurus_") and _Microraptor_.  BPM 1 3-13 shows several advanced
osteological features (stiffened dromie-like tail; "sickle-claw";
hourglass-shaped sternum composed of two sternal plates and with sockets for
the sternal ribs; semilunate carpal that caps mc's 1 and 2), but lacks
avialan features such as unserrated teeth, short tail, and reversed hallux.

Integumentary fibres are distributed over the entire body of BPM 1 3-13.
However, those associated with the back of the forelimbs and hindlimbs and
end of the tail are the focus of this paper: these are clearly in possession
of a rachis and barbs, conforming to the 'modern' (pinnate) morphology,
hitherto described for _Caudipteryx_, _Protarchaeopteryx_ and
incontrovertible birds.  Interestingly, the tail feathers produce a longer
plume than _Caudipteryx_ or _Archaeopteryx_.  All pinnate feathers described
for BPM 1 3-13 have symmetrical vanes.

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.

I find the development of pinnate feathers along the forelimbs AND the
hindlimbs extremely interesting.  It brings to mind William Beebe's
hypothetical proavian ("Tetrapteryx"), as well as the analogy of parachuting
and gliding primates.  The latter are thought to use the long, shaggy hair
along the arms and legs as a gliding surface in aerial locomotion.  Of
course, these critters are all arboreal...


Tim


------------------------------------------------------------ 

Timothy J. Williams 

USDA-ARS Researcher 
Agronomy Hall 
Iowa State University 
Ames IA 50014 

Phone: 515 294 9233 
Fax:   515 294 3163