Re: [dinosaur] Alcmonavis, new avialan from Late Jurassic of Germany (free pdf)

[Tim Williams <tijawi@gmail.com>]

> Oliver WM Rauhut, Helmut Tischlinger & Christian Foth (2019)
> A non-archaeopterygid avialan theropod from the Late Jurassic of southern 
> Germany.
> eLife 8:e43789


Hopefully one day a more complete skeleton of _Alcmonavis_ will turn
up; but as it stands, this is still a very cool discovery.  I'm
impressed by the discussion of the musculature, particularly the
implications for flapping flight and a ground-level take-off.  This is
one of many recent studies that favor a 'flapping-start' origin to
avian flight.

This observation by the authors was intriguing: "Outside avialans, a
marked tuberculum bicipitale radii is only present in _Microraptor_
(IVPP V 13352) and, apparently in hypertrophied form, in _Bambiraptor_
(Burnham, 2004). Thus, with the exception of _Bambiraptor_, a marked
tubercle for the insertion of m. biceps brachii seems only to be
present in volant forms."

Based on previous studies, it seems quite reasonable to infer that
_Microraptor_ might have been capable of powered flight.  By contrast,
_Bambiraptor_ has not usually been regarded as volant.  But I wouldn't
rule out _Bambiraptor_ being capable of some form of flapping flight,
particularly in juveniles.  Limited flight ability was suggested for
juvenile _Bambiraptor_ by Paul (2010; Princeton Field Guide), who
cited the long arms and hands.  The total length of the type specimen
(subadult?) was only slightly longer than a large _Microraptor_
("_Microraptor hanqingi_") at ~95 cm - although _Bambiraptor_ was
likely heavier than the 2 kg estimated for the latter.  However, based
on _Archaeopteryx_, small paravians in general may have had more
lightweight skeletons than previously assumed (Schwartz et al., 2019).
Indirectly, Rauhut et al. may provide further evidence for flapping
flight in _Bambiraptor_ (especially juveniles), including take-off.