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Re: Balaur, predatory dromaeosaurid or omnivorous flightless bird? (free pdf)

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On Thu, Jun 18, 2015 at 8:27 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
> A new open access paper:
> Andrea Cau, Tom Brougham &  Darren Naish (2015)
> The phylogenetic affinities of the bizarre Late Cretaceous Romanian
> theropod Balaur bondoc (Dinosauria, Maniraptora): dromaeosaurid or
> flightless bird?
> PeerJ 3:e1032
> doi: https://dx.doi.org/10.7717/peerj.1032
> https://peerj.com/articles/1032/
> The exceptionally well-preserved Romanian dinosaur Balaur bondoc is
> the most complete theropod known to date from the Upper Cretaceous of
> Europe. Previous studies of this remarkable taxon have included its
> phylogenetic interpretation as an aberrant dromaeosaurid with
> velociraptorine affinities. However, Balaur displays a combination of
> both apparently plesiomorphic and derived bird-like characters. Here,
> we analyse those features in a phylogenetic revision and show how they
> challenge its referral to Dromaeosauridae. Our reanalysis of two
> distinct phylogenetic datasets focusing on basal paravian taxa
> supports the reinterpretation of Balaur as an avialan more crownward
> than Archaeopteryx but outside of Pygostylia, and as a flightless
> taxon within a paraphyletic assemblage of long-tailed birds. Our
> placement of Balaur within Avialae is not biased by character
> weighting. The placement among dromaeosaurids resulted in a suboptimal
> alternative that cannot be rejected based on the data to hand.
> Interpreted as a dromaeosaurid, Balaur has been assumed to be
> hypercarnivorous and predatory, exhibiting a peculiar morphology
> influenced by island endemism. However, a dromaeosaurid-like ecology
> is contradicted by several details of Balaur’s morphology, including
> the loss of a third functional manual digit, the non-ginglymoid distal
> end of metatarsal II, and a non-falciform ungual on the second pedal
> digit that lacks a prominent flexor tubercle. Conversely, an
> omnivorous ecology is better supported by Balaur’s morphology and is
> consistent with its phylogenetic placement within Avialae. Our
> reinterpretation of Balaur implies that a superficially
> dromaeosaurid-like taxon represents the enlarged, terrestrialised
> descendant of smaller and probably volant ancestors.