. A diapsid reptile from the Pennsylvanian of Kansas. Reptiles, Fossil -- Kansas; Paleontology -- Pennsylvanian; Paleontology -- Kansas. i (111 Fic. 19.—Petrohcosanrus kamensis hane. Reconstruction of tlie right humerus, X (A-D) Proximal dor- sal, proximal ventral, distal dorsal and distal ventral surfaces, based mainly on KUVP 9957 and 33606a. Limbs A total of twenty-six limbs, belonging to fourteen individuals have been recovered. Most of these were originally complete as they lay in the matrix. Only eight were com- pletely isolated from the body. Of the limbs associated with the girdle
. A diapsid reptile from the Pennsylvanian of Kansas. Reptiles, Fossil -- Kansas; Paleontology -- Pennsylvanian; Paleontology -- Kansas. i (111 Fic. 19.—Petrohcosanrus kamensis hane. Reconstruction of tlie right humerus, X (A-D) Proximal dor- sal, proximal ventral, distal dorsal and distal ventral surfaces, based mainly on KUVP 9957 and 33606a. Limbs A total of twenty-six limbs, belonging to fourteen individuals have been recovered. Most of these were originally complete as they lay in the matrix. Only eight were com- pletely isolated from the body. Of the limbs associated with the girdles, only one was in articulation (KUVP 9957a, Fig. 17). Humerus.—The reconstruction of the hu- merus (Fig. 19) is based mainly on two ma- ture but crushed bones, found in KUVP 9957a and 33606a. The humerus is of the tetrahe- dral type common to primitive reptiles (Holmes, 1977) but the shaft is better de- veloped than in primitive captorhinomoiphs and pelycosaurs. The width of the proximal end of the humerus forms about 27 per cent of the length of the bone, and the distal width is about 29 per cent of the length. The shaft is exceedingly slender, only about 7 per cent of the length. These proportions are compara- ble to those found in Araeoscelis (Vaughn, 1955). The estimated twist of the distal upon the proximal plane is 60 degrees. Following Romer and Price's (1940) terminology, the humeral surfaces in Petrolacosaurus can be divided into proximal dorsal, distal dorsal, proximal ventral and distal ventral surfaces. The proximal dorsal surface was probably gently convex along the long axis of the bone. Severe crushing flattened the proximal head. The surface shows a distinct ridge for the M. latissinius dorsi. A long narrow ridge for the M. deltoideus insertion runs distally from the delto-pectoral crest. The proximal ventral surface was probably deeply concave below the articular surface. Tlie M. coracobrachialis brcvis inserted in the concave region. The anterior proximal
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Keywords: ., bookcentury1900, bookcollectionbi, booksubjectpaleontologykansas
