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Re: Eosinopteryx, new paravian from China
I just measured the outer curvature of the D-IV ungual. I used the larger photo
available from Andrea Cau. The photo is fuzzy when zoomed in, so making out the
actual tip is estimated, and might be underestimating. Plus, if the ungual is
even slightly oblique (with respect to the photo), then the curvature value
will be decreased. Hence the following value is a minimum.
Outer curvature for D-IV-5 is 69.1 degrees.
This compares with values for D-IV-5's:
Deinonychus 91.6; 65.9; 87
Bambiraptor 81.7, 85.5
Data from Fowler et al., 2011 (not cited in Godefroit et al.)
So... are these claws really all that weakly curved? they're at the lower end
of the scale, but not all that surprising. Given that other unguals (e.g. D-II)
in the specimen are slightly oblique, it wouldn't surprise me if the D-IV was
too, so add a few degrees and it's not that different at all.
Also, fusion of caudal neural arches does not say anything about maturity.
Alligators can have fused caudals even in the embryo (Brochu ?98). See
discussion in our Raptorex paper. You can't tell from the photos provided if
the other verts are fused (not that this would mean much). The specimen needs
histological sampling of a limb bone; until then, all bets are off regarding
From: Tim Williams <email@example.com>
Sent: Wednesday, 23 January 2013, 0:41
Subject: Re: Eosinopteryx, new paravian from China
> Pascal Godefroit, Helena Demuynck, Gareth Dyke, Dongyu Hu, François
> Escuillié & Philippe Claeys (2013)
> Reduced plumage and flight ability
new Jurassic paravian theropod
> from China
> Nature Communications 4, Article number: 1394
The relative size of the pedal phalanges of _Eosinopteryx_ (especially
short penultimate phalanges) and the short, poorly recurved pedal
unguals are cited in support of a "ground dwelling, ‘cursorial’
mode-of-life as in many living birds".
However, the situation is a bit more complicated than that.
_Deinonychus_ has elongate penultimate phalanges and highly recurved
unguals. But nobody would accuse _Deinonychus_ of being arboreal (at
least not to its face). These pedal characters of _Deinonychus_ are
associated with improved grasping ability by the pes - and no doubt
related to predation.
So it may mean that the feet of _Eosinopteryx_ were used less for
grabbing and killing things than dromaeosaurids, and even other
troodontids. This might be connected with the rather short snout of
_Eosinopteryx_. There's quite a few things about _Eosinopteryx_ that
remind me of basal oviraptorosaurs like _Caudipteryx_.