In 2006, Wilkinson, Unwin, and Ellington published a paper "High lift function of the pteroid bone and forewing of pterosaurs." (Proc. Roy. Soc. Lond., B, 273:119-126), in which they noted that I had argued that 1) a sesamoid articulated with the distal fovea of the preaxial carpal and 2) the pteroid articulated with the side of the preaxial carpal. Unable to find any such facet on the side of the preaxial carpal, and apparently unwilling to ask me for help, they rejected my interpretation. In response to that paper, I presented a talk at the 65th Annual Meeting of the Society of Vertebrate Paleontology in Ottawa, Canada, during which I offered a reward for any and all specimens that actually preserved a pteroid bone articulated in the fovea of the preaxial carpal, and I also published a rebuttal paper "Articulation and function of the pteroid bone of pterosaurs" (JVP, 27:881-891 ). On page 887 of that paper, I described the articular facet on preaxial carpals of Pteranodon as follows: "In Pteranodon the articular surface on the preaxial carpal is an indistinctly marked convex oval on the medial surface (Fig. 7), though in KUVP 2066 and YPM 2499, old individuals with prominent muscle attachment scars, the articular surface is surrounded by rugose bone that probably represents the margin of the joint capsule. The fact that the articular surface is indistinct indicates that the joint was not as well developed as other forelimb joints, probably because it was only lightly loaded in compression."  Here is Fig. 7 (minus labels) from my paper showing the medial aspect of three right preaxial carpals: A) KUVP 2120; B) KUVP 2072; and C) YPM 2414 (The small gradations in the scales are mm). When you mouseover a carpal, a red oval outlining the articular facet for the pteroid will appear. Note that the articular facet looks different in C because of a different quality of preservation. "Given that the articular surface for the pteroid on the preaxial carpal is indistinct in mature specimens of Pteranodon, it should be virtually invisible in the immature specimens of Anhanguera, and so it is. There is almost no visible trace of an articular surface and the faint articular surface of the left preaxial carpal of AMNH 22555 shows up better in the photograph during preparation (Fig. 5A) than with the freed bone in hand. The articular surface lies in the same place as the convex oval articular surface in Pteranodon on the medial surface of the preaxial carpal and forms a saddle-shaped surface that is complementary to the saddle-shaped articular end of the pteroid." The Fig. 5A referred to in the above quotation was a photo of AMNH 22555 during acid preparation kindly provided to me by Peter Wellnhofer, which shows the pteroid articulation better than the completely freed bone does. Below I reproduce the Fig. 5A:  The medial aspect of the left preaxial carpal is visible (upper right), whereas the right preaxial carpal somewhat below it presents its lateral aspect.The articular surface for the pteroid (asp) is faintly visible. Abbreviations: art, articular surface for fovea; asp, articular surface for pteroid; ds, distal syncarpal; mciv, metacarpal IV; pc, preaxial carpal; ps, proximal syncarpal; pt, pteroid; r, radius; str, striations for attachment to its tendon; u, ulna; and sesA, Sesamoid A. In October 2008 at the 68th Annual Meeting of the Society of Vertebrate Paleontology in Cleveland, Ohio, Dave Unwin presented a talk [with co-authors Matt Wilkinson and Lü Junchang] in which he conceded that the pteroid did not articulate in the distal fovea of the preaxial carpal but continued to state that they could not see any articular surface for the pteroid on the medial aspect of the preaxial carpal. Okay, here is the Eye Test. Below I present a high resolution image of the medial aspect of the left preaxial carpal of AMNH 22555, though rotated 90° to the left relative to the image above. The original photograph provided to me by Peter Wellnhofer, which on the back claims to have been printed at actual size, was scanned at 600 dpi (the maximum non-interpolated resolution of my Acer Acerscan Prisa 610S scanner), and the image below was cropped from the resulting scan, but has not otherwise been reduced or manipulated in any way. Examine the photo, and if you think you can see the articular facet for the pteroid, then mouseover the facet. If you are correct, a red oval will appear and you pass the test. If you cannot find the articular facet, no red oval will appear and you fail the test. If you pass the test and find the articular surface within the red oval, then click your mouse within that oval and see what happens. 
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