Beipiaosaurus and sauropod ancestry

[HPBredow@aol.com]

Jeff Pooling wrote in his Journal of Dinosaur Paleontology  "New feathered 
dinosaur found" about the new therizinisauroid Beipiaosaurus: 
"The specimen shows certain anatomical characteristics closer to those of 
oviraptorids than advanced therizinosaurs. This suggests that the five-toed 
feet of therizinosaurs were not inherited from prosauropod ancestors, but 
were evolved independently from four-toed theropod ancestors.

There's the following statement about sauropod evolution in The Complete 
Dinosaur:
"The frequent assumption that they [sauropods] arose from prosauropods, 
probably melanosaurids, has yet to be verified. Furthermore, some characters, 
including the reduction of the fifth digit of the hind foot in all 
prosauropods (but not in sauropods), suggest that these animals were already 
too specialised to have served as sauropod ancestors, and that the sauropods 
may have arisen as a sister group in the Late Triassic."

Now I wonder if such a redevelopment of the fifth toe in therizinosauroids 
took really place, shouldn't it also be possible for sauropods to do the 
same? So this single character wouldn't preclude a prosauropod ancestry of 
sauropods? 


Heinz Peter Bredow
Bremen
Germany