|Fossil tail feathers of S. cooperorum, from O'Connor et al., 2009.|
S. cooperorum itself is most well-known for its elaborate tail made up of six ribbon-like feathers. Those feathers overlapped at the base, and may have acted as an air brake for precise landings with the feet on small branches. It's possible that most other enantiornitheans, which lacked long feathery tails and also retained wing claws, landed by simply smacking clumsily into tree trunks or brush and grabbing on with all four limbs.
Given the more advanced pectoral anatomy of enantiornitheans (often with mysterious adaptations like little antler-shaped processes on the sternum), it's difficult to envision a purely gliding mode of flight for them, but the lack of braking mechanisms and retention of wing claws in many would make an odd sort of sense if these things relied heavily on simply making prolonged jumps between trees. Having independently evolved an arboreal ecology separately from modern birds, and being derived from relatively basal avialans with rather weak flapping abilities, some odd mode of flight or near-flight specifically tailored to living in tree canopies should be investigated in future studies, at least.
|Type specimen of L. hani, from Hou et al. 2004. Note the poor preservation of the tail feathers.|
|Hind limbs and tail from the type specimen of R. pani, from Morschhauser et al. 2009. Am I seeing things here?|
*Longirostravisinae was implicitly named by Zhou and Zhang 2006 when they named Longirostravisidae, though most recent analyses find this to be a sub-group of Longipterygidae. It hasn't yet been defined phlyogenetically, but it's roughly everything closer to Longirostravis than to Longipteryx, though some Longipteryx-like fossils such as "Camptodontus" yangi and Boluochia haven't yet been included in longipterygid analyses as far as I'm aware. (Image at left: restoration of Shanweiniao cooperorum by Matt Martyniuk, all rights reserved).
- Hou, Chiappe, Zhang and Chuong, 2004. "New Early Cretaceous fossil from China documents a novel trophic specialization for Mesozoic birds." Naturwissenschaften, 91(1): 22-25.
- Morschhauser, Varricchio, Gao, Liu, Wang, Cheng and Meng, 2009. "Anatomy of the Early Cretaceous bird Rapaxavis pani, a new species from Liaoning Province, China. Journal of Vertebrate Paleontology, 29(2): 545-554.
- O'Connor, Wang, Chiappe, Gao, Meng, Cheng and Liu, 2009. "Phylogenetic support for a specialized clade of Cretaceous enantiornithine birds with information from a new species." Journal of Vertebrate Paleontology, 29(1): 188-204.