[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Sereno's paper & uncinate processes

        While browsing through Sereno's new dinosaur paper, I noticed in
figure 5 he cites "ribs with uncinate processes" as a character linked to '
powered flight in birds.  Actually, uncinate processes have a wider 
distribution than this, as crocodiles possess them (Duncker, 1978, fig. 8).
Uncinate processes also occur in tuataras, ankylosaurs, Huayangosaurus,
Euparkeria and apparently, the "fighting" Velociraptor.
        It has been recently suggested (Hou et al 1996) that uncinate
processes are functionally linked to endothermy and high levels of oxygen 
consumption, so that early birds whick lacked them were incapable of high 
levels of sustained activity, and were ectothermic.  The above examples
document that uncinate processes are not restricted to endotherms, 
in addition to the fact that some living birds lack them ((d'A. Bellairs
& Jenkin, 1960).

        Sereno, P.C. (1997).  The origin and evolution of dinosaurs.  Annual
Reviews of Earth and Planetary Sciences, 25, 435-489.
        Duncker, H.R. (1978).  General morphological principles of amniotic
lungs.  pp. 2-15 in Piiper, J. (Ed). Respiratory Function in Birds, Adult
and Embryonic.  Springer-Verlag, New York.
        Hou, L., Martin, L.D., Zhou, Z., & Feduccia, A. (1996).  Early 
adaptive radiation of birds: evidence from fossils from northeastern
China.  Science, 274, 1164-1167.
        d'A. Bellairs, A. & Jenkin, C.R. (1960).  The skeleton of birds.
pp. 241-300 in Marshall, A.J. (Ed). Biology and Comparative Physiology of
Birds.  Vol. 1.  Academic Press, New York.

Guy Leahy
Dept. of PEHR
Western Washington University
Bellingham, WA 98225