RE: Feduccia et al: No Evidence Fossil Feathers Are Really Feathers

[Tim Williams <twilliams_alpha@hotmail.com>]

Hmmm... not only does Feduccia re-classify microraptors as birds, but he 
also re-classifies psittacosaurs as ornithopods.  Maybe he read Butler's 
paper...  (Guffaw guffaw.)

I'm also not sure what the presence of scales in the forearm of 
_Pelecanimimus_ adds to this 'debate'.  Birds have scales on their feet, so 
why is this a big deal?

And somebody has just GOT TO explain to Feduccia the distinction between 
"ancestor" and "sister taxon".  I think even the most hard-headed 
paleontologist recognizes that an ancestor cannot give rise to a descendent 
that lived 25 million years earlier.

Feduccia, A., Lingham-Soliar, T., and Hinchliffe, J.R. (2005). Do feathered 
dinosaurs exist? Testing the hypothesis on neontological and paleontological 
evidence. J. Morphology (in press).

Abstract. "The origin of birds and avian flight from within the archosaurian 
radiation has been among the most contentious issues in paleobiology.  
Although there is general agreement that birds are related to theropod 
dinosaurs at some level, debate centers on whether birds are derived 
directly from highly derived theropods, the current dogma, or from an 
earlier common ancestor lacking suites of derived anatomical characters.  
Recent discoveries from the Early Cretaceous of China have highlighted the 
debate, with claims of the discovery of all stages of feather evolution and 
ancestral birds (theropod dinosaurs), although the deposits are at least 25 
million years younger than those containing the earliest known bird 
_Archaeopteryx_.  In the first part of the study we examine the fossil 
evidence relating to alleged feather progenitors, commonly referred to as 
protofeathers, in these putative ancestors of birds.  Our findings show no 
evidence for the existence of protofeathers and consequently no evidence in 
support of the follicular theory of the morphogenesis of the feather.  
Rather, based on histological studies of the integument of modern reptiles, 
which show complex patterns of the collagen fibers of the dermis, we 
conclude that protofeathers are probably the remains of collagenous fiber 
meshworks that reinforced the dinosaur integument.  These meshworks of the 
skin frequently formed aberrant patterns resembling feathers as a 
consequence of decomposition. Our findings also draw support from new 
paleontological evidence.  We describe integumental structures, very similar 
to protofeathers, preserved within the rib area of a _Psittacosaurus_ 
specimen from Nanjing, China, an ornithopod dinosaur unconnected with the 
ancestry of birds.  These integumental structures show a strong resemblance 
to the collagenous fiber systems in the dermis of many animals.  We also 
report the presence of scales in the forearm of the theropod ornithomimid 
(bird mimic) dinosaur, _Pelecanimimus_, from Spain.  In the second part of 
the study we examine evidence relating to the most critical character 
thought to link birds to derived theropods, a tridactyl hand composed of 
digits 1-2-3.  We maintain the evidence supports interpretation of bird wing 
digit identity as 2,3,4, which appears different from that in theropod 
dinosaurs.  The phylogenetic significance of Chinese microraptors is also 
discussed, with respect to bird origins and flight origins.  We suggest that 
a possible solution to the disparate data is that Aves plus bird-like 
maniraptoran theropods (e.g., microraptors and others) may be a separate 
clade, distinctive from the main lineage of Theropoda, a remnant of the 
early avian radiation, exhibiting all stages of flight and flightlessness."


Cheers

Tim