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RE: Sinocalliopteryx (Theropoda: Compsognathidae) ate confuciusornithids and dromaeosaurids

But but... surely O'Connor et al. (2011) showed it's most reasonable to 
conclude associated arboreal birds in a theropod's stomach mean the theropod is 
probably arboreal.  Arboreal Sinocalliopteryx, here we come!

Seriously though, it's good to see a refutation of that silly line of evidence 
in print.  As Xing et al. state-

"O’Connor et al. [54] reported on a specimen of Microraptor
 with the remains of an enantiornithine bird within its abdominal 
cavity, and argued that such presumed predation on a bird with clear 
arboreal perching adaptations was evidence supporting a highly 
arboreal/aerial lifestyle in Microraptor. Based on various 
other lines of evidence, we agree with this ultimate conclusion; 
however, that Jehol birds were evidently on the menu of Sinocalliopteryx must 
be regarded as a strong contradiction to the necessity of O’Connor et al’s [54] 
ecological inference. Confuciusornis
 was not as well adapted to perching as enantiornithine birds, but does 
nonetheless possess long curved pedal claws and a posteriorly-facing 
hallux, and was capable of powered flight. While Sinocalliopteryx
 does have proportionately longer arms than most compsognathids and may 
have been capable of tree climbing, it lacks any definitive arboreal 
adaptations; at over two meters in length, is best regarded as a 
predominantly terrestrial animal.

Active hunting
 of flight-capable prey by a land-bound predator may seem intrinsically 
implausible, but there are abundant extant examples, wild felids among 
the most famous. The back-footed cat (Felis nigripes) of southern Africa 
routinely ambushes and chases down cursorial birds before they are able to 
become airborne [56]. Servals (Leptailurus serval) are long-legged and adept at 
pouncing on alighted birds, and at snagging fleeing birds midair [57]–[59]. 
Avian prey is known to constitute nearly half the diet of some leopard cats 
(Prionailurus bengalensis) [60],
 which both climb trees to prey on roosting birds and ambush foraging 
birds on the ground. Among canids, foxes are expert bird hunters, 
commonly taking anseriforme, galliforme, and passeriforme game [61], [62]. 
Among extant reptiles, monitor lizards and various snakes consume birds in both 
arboreal and terrestrial contexts [63]–[66]."
Mickey Mortimer

> Date: Wed, 29 Aug 2012 14:37:37 -0700
> From: bcreisler@gmail.com
> To: dinosaur@usc.edu
> Subject: Sinocalliopteryx (Theropoda: Compsognathidae) ate confuciusornithids 
> and dromaeosaurids
> From: Ben Creisler
> bcreisler@gmail.com
> New in PLoS ONE:
> Lida Xing, Phil R. Bell, W. Scott Persons, Shuan Ji, Tetsuto
> Miyashita, Michael E. Burns, Qiang Ji & Philip J. Currie (2012)
> Abdominal Contents from Two Large Early Cretaceous Compsognathids
> (Dinosauria: Theropoda) Demonstrate Feeding on Confuciusornithids and
> Dromaeosaurids.
> PLoS ONE 7(8): e44012.
> doi:10.1371/journal.pone.0044012
> http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0044012
> Two skeletons of the large compsognathid Sinocalliopteryx gigas
> include intact abdominal contents. Both specimens come from the
> Jianshangou Beds of the lower Yixian Formation (Neocomian), Liaoning,
> China. The holotype of S. gigas preserves a partial dromaeosaurid leg
> in the abdominal cavity, here attributed to Sinornithosaurus. A
> second, newly-discovered specimen preserves the remains of at least
> two individuals of the primitive avialan, Confuciusornis sanctus, in
> addition to acid-etched bones from a possible ornithischian. Although
> it cannot be stated whether such prey items were scavenged or actively
> hunted, the presence of two Confuciusornis in a grossly similar state
> of digestion suggests they were consumed in rapid succession. Given
> the lack of clear arboreal adaptations in Sinocalliopteryx, we suggest
> it may have been an adept stealth hunter.