Jeholornis: Two-Tailed Wonder

[Jason Brougham <jaseb@amnh.org>]

News today of a more proximal tail fan in Jeholornis:

Jingmai O’Connor, Xiaoli Wang, Corwin Sullivan, Xiaoting Zheng, Pablo Tubaro, 
Xiaomei Zhang, and Zhonghe Zhou
Unique caudal plumage of Jeholornis and complex tail evolution in early birds 
PNAS 2013 ; published ahead of print October 7, 2013, 
doi:10.1073/pnas.1316979110 

We describe the presence of essentially two functional tails in the Early 
Cretaceous Jeholornis (the second most primitive bird)—one like that of some 
modern birds with a fan-shaped tract of feathers over the proximal tail 
vertebrae and another distal frond like that of feathered dinosaurs such as 
Caudipteryx and Microraptor. We suggest that the unique “two-tail” plumage in 
Jeholornis probably evolved as the result of complex interactions between 
natural and sexual selective pressures and served both aerodynamic (flight and 
balance, etc.) and ornamental functions (communication/display, etc.). Our 
aerodynamic analysis also provides a plausible functional explanation for the 
elongation of the boney tail in Jeholornis relative to Archaeopteryx. 

http://www.pnas.org/content/early/2013/10/02/1316979110.abstract?sid=8ba0510d-473b-46ef-9aa7-b4dcf8d88096