It’s May 2, 2015 and I’m going to let this blogpost stand unaltered, but please see May 2, 2015 for notes that the so-called styliform process is really just a displaced ulna.
The big news today is the announcement of a new Chinese dinosaur/bird, Yi Qi, with a long wrist bone that extended into soft membranes trailing the forelimb, likely to extend them like a bat wing (Fig. 1).
Two possible reconstructions were offered (Fig. 1). I offer below a new reconstruction that does not have the forelimbs overextended at the elbow and shoulders.
From the Xu et al. abstract:
“Most surprisingly, Yi has a long rod-like bone extending from each wrist, and patches of membranous tissue preserved between the rod-like bones and the manual digits. Analogous features are unknown in any dinosaur but occur in various flying and gliding tetrapods, suggesting the intriguing possibility that Yi had membranous aerodynamic surfaces totally different from the archetypal feathered wings of birds and their closest relatives.”
Added June 3, 2021:
The published reconstructions by Xu et al. 2015 are bogus.
There is no extra bone, only a displaced ulna suffering from a torsion fracture. Corrections offered below (Fig. 2).
Xu X, Zheng X-T, Sullivan C, Wang X-L, Xing l, Wang Y, Zhang X-M, O’Connor JK, Zhang F-C and Pan Y-H 2015. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings.Nature (advance online publication)