. Bulletin. Natural history; Natuurlijke historie. 1 90 cm FIG. 6L Outline sketches of the carpus and metacarpus (in part) of Deinonychus antirrhopus illustrate the nature of the joints between the carpus and epipodials (A and B) and the carpus and metacarpals (A and C). The dashed arc of A parallels the articular arc (heavy curve) formed by the radiale and the internal proximal part of the first metacarpal. This arc covers 190° ± and produced a wide angle of adduction-abduction of the manus on the epipodials. This adduction- abduction arc was not planar, but curved (twisted) through about 45°
. Bulletin. Natural history; Natuurlijke historie. 1 90 cm FIG. 6L Outline sketches of the carpus and metacarpus (in part) of Deinonychus antirrhopus illustrate the nature of the joints between the carpus and epipodials (A and B) and the carpus and metacarpals (A and C). The dashed arc of A parallels the articular arc (heavy curve) formed by the radiale and the internal proximal part of the first metacarpal. This arc covers 190° ± and produced a wide angle of adduction-abduction of the manus on the epipodials. This adduction- abduction arc was not planar, but curved (twisted) through about 45° during adduction, as is shown in B. The dashed curve of B traces the plane of adduction-abduction from a fully ab- ducted position at left to a fully adducted position at the right. The 45° angle between arrows A and B is the amount of rotation (supination) that occurred during adduction. The dotted lines of C outline the proximal ends of the metacarpals, relative to the two carpals (solid lines). Abbreviations: rd—radiale; un—ulnare; I, II and III—metacarpals I, II and III. pitted, concave, ventral side of that bone. Unless it did not contact the radiale at all, there seems to be no other possible position, for all other possible surfaces of the radiale are known to articulate with other elements. The proximal ulnare surface is oval and distinctly concave. Considering the movement of the radiale against the radius, this concavity probably per- mitted a simple sliding movement, with some rotation, across the expanded ventral or posterior portion of the ulnar condyle. The distal surface presents another surprise. Unlike the shallow, flat facets for the first and second metacar- pal, that for metacarpal III is a broad, smooth convexity which is almost cylindrical. The best specimens show this to be faintly saddle-shaped, being strongly convex vertically (short axis) and slightly concave transversely (the long dimension), as shown in Figure 60E and F. This convex facet
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Keywords: ., bookcentury1900, bookcollectionbiodiv, booksubjectnaturalhistory
