A long-tailed bird with a pygostyle

[Brad McFeeters <archosauromorph2@hotmail.com>]

Lü, Junchang & Lianhai Hou, 2005.  A possible long-tailed bird with a 
pygostyle from the late Mesozoic Yixian Formation, western Liaoning, China.  
Acta Geologica Sinica 79 (1): 7-10.

Abstract:  An incomplete caudal vertebral series (IVPP V11309) from the 
Yixian Formation of late Mesozoic, Jianshangou area of Beipiao, western 
Liaoning Province, may represent a new bird. The tail is composed of at 
least 12 free caudal vertebrae and the most distal 5 caudal vertebrae 
co-ossified into a pygostyle. The pygostyle is plate-like and slightly 
curved dorsally. The anterior free caudals are amphiplatyan. The anterior 
caudal surfaces of the last three free caudals are concave, but their 
posterior articular surfaces are convex. The pygostyle is regarded as the 
first appeared flight apparatus during the evolutionary process from 
*Archaeopteryx* to neornithes. The pygostyle appeared in most early fossil 
birds and almost all the modern birds. Although their morphologies are 
different, they are basically formed by at least four last caudal vertebrae. 
The specimen V11309 is regarded as a bird rather than a non-avian theropod 
dinosaur based on the following characters: short caudal vertebrae, numerous 
pits present on the surfaces of the centra and, a foramen present between 
the basal part of the fused neural spines, which is similar to that of 
*Struthio camelus*. The discoveries of pygostyles from the therizinosauroids 
and oviraptorosaurs may provide strong evidence for supporting the origin of 
birds from small theropod dinosaurs. The structure of the pygostyle in 
specimen V11309 is different from those of *Beipiaosaurus* 
(Therizinosauroid) and *Nomingia* (oviraptorosaur). The most parsimonious 
interpretation is that these pygostyle-like structures are independently 
acquired by *Beipiaosaurus* and *Nomingia* during their evolutionary 
process.

Looks like no new taxon named this time, but I cannot be sure having seen 
only the abstract.