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New Mesozoic bird papers (advance publication)

From: Ben Creisler

In case these advance online-publication papers have not 
been mentioned yet:

David A. Burnham; Alan Feduccia; Larry D. Martin; Amanda 
R. Falk (2010) 
Tree climbing -- a fundamental avian adaptation.  
Journal of Systematic Palaeontology (advance online 

There have been a number of studies on the claws of 
Mesozoic birds, largely driven by interest in the habitat 
of Archaeopteryx. Many Mesozoic avians have large, well 
formed manual claws, largely absent in contemporary 
birds. Juvenile hoatzins are the only living birds with 
claws that are large enough to be generally functional, 
but not equivalent to those of Mesozoic birds. When birds 
developed an effective backstroke permitting easy ascent 
from flat surfaces, the need for manual claws 
disappeared, which would suggest that they were primarily 
used for climbing tree trunks and had little function in 
prey capture. This hypothesis has both phylogenetic and 
functional implications. The numerous claw studies to 
date are based primarily on measurements taken of the 
bony core, all that is usually preserved in fossils. 
Examination of contemporary birds shows that this is a 
poor estimator of the size and shape of the horny sheath 
that actually forms the functional claw. The discovery of 
vast numbers of exceptionally preserved fossil birds from 
the Late Jurassic and Early Cretaceous of China means 
that we now have an opportunity to compare actual horny 
claw data from the earliest birds with that of modern 
birds and test hypotheses on climbing, terrestrial 
activity, and predation.  

Jingmai K. O'Connor; Zhonghe Zhou; Fucheng Zhang (2010)
A reappraisal of Boluochia zhengi (Aves: Enantiornithes) 
and a discussion of intraclade diversity in the Jehol 
avifauna, China.  
Journal of Systematic Palaeontology (advance online 

A careful reappraisal of the only known specimen of the 
poorly understood fossil enantiornithine bird Boluochia 
zhengi reveals numerous morphological similarities that 
suggest this taxon is closely related to the well-known 
Longipteryx chaoyangensis, and so is assignable to the 
most diverse recognized clade of Early Cretaceous 
enantiornithines, the Longipterygidae. This new study of 
the holotype of B. zhengi reveals new longipterygid 
synapomorphies and expands our knowledge of the temporal 
and geographical ranges and diversity of the clade. We 
suggest that the trophic specialization that 
characterizes longipterygids may have been a major factor 
contributing to the success of this clade.  

Zhonghe Zhou; Larry D. Martin (2010)
Distribution of the predentary bone in Mesozoic 
ornithurine birds.
Journal of Systematic Palaeontology (advance online 

In this paper we review the distribution of the 
predentary bone in Mesozoic ornithurine birds. The 
predentary bone, well known in ornithischian dinosaurs, 
has now been reported not only in hesperornithids and 
ichthyornithids but also in a number of Early Cretaceous 
basal ornithurines, such as Yanornis, Yixianornis, 
Hongshanornis and Jianchangornis. In many Early 
Cretaceous ornithurines the predentary bone is not 
preserved, but the anterior end of the dentary has a 
blunt, often inclined margin and usually shows a 
distinctive pit. These are characteristic features of a 
predentary attachment. The predentary bone is absent in 
extant birds, and examination of known enantiornithines 
and more basal avians now represented by hundreds of 
specimens show that none of them preserved a predentary 
bone, confirming that this bone was independently derived 
in the Ornithurae, and lost in the Neornithes. The 
predentary bone is found to be associated with both 
toothed and edentulous dentaries in basal ornithurines. 
In toothed birds the edentulous predentary bone always 
corresponds to an edentulous anterior portion of the 
premaxilla. Although it is possible that the presence of 
the predentary bone is related to a piscivorous diet in 
some birds, this may not be true for all the basal 
ornithurines with a predentary bone. It is almost certain 
that it was functionally very different from the 
predentary bone in ornithischian dinosaurs.