Joan Echols

“ One distinctive bone may represent the basal plate of the posterior dorsal fin. This incomplete specimen shows two projecting curved processes, bearing low but distinct ridges, which diverge, probably anteriorly. The central portion is narrow. The two ridges continue onto the posterior portion. This has been broken off, but shows that the ridges diverge again. The surface is smooth, except for the ridges. As before, orientation is uncertain. On no. 786F this fin was interpreted by Hibbard (1933:281) as the anal fin. ”

“ In viewing the changes in the endocranium of Carboniferous and Permian coelacanths, it would be well to consider the mechanical relationship of the loss of the basipterygoid processes to the effect on swallowing prey. Evidently many of the coelacanths, Latimeria for example, are predators (Smith, 1939:104) ; to such fishes a more efficient catching and swallowing mechanism would be an adaptive improvement. ”

“ A low ridge, nearly vertical, passes dorsally from about mid-point of the canal to the dorsal portion. The anterior margin is nearly straight, the ventral margin is concave, and the dorsal margin is convex dorsally but may be incomplete. Perhaps the squamosal and preopercular are fused. The surface appears smooth; the view may be of the medial side. The squamosal of R. elegans is nearly triangular and notably different from that of Synaptotylus newelli.
The subopercular (fig. 3) shows closely spaced tubercles on the lateral surface. ”

“ The medial surface is concave, steepest near the anterior margin, and then slopes outward evenly. In medial view one specimen (K. U. no. 11426) shows a small, caudally directed projection of bone, evidently for articulation of the fin-skeleton, at the widest portion of the cleithrum. Sutures on several specimens were indistinct. Broken specimens show sutural faces, but many nearly complete specimens show little or no indication of sutures, without regard to size of the girdles. The internal structure of the fin was not observed. ”

“ A new genus of Pennsylvanian coelacanths, Synaptotylus, is described and a previously named species, Coelacanthus newelli Hibbard, 1933 (C. arcuatus Hibbard, 1933, is a junior synonym) , is referred to this genus. All specimens of Synaptotylus newelli (Hibbard) were collected from the Rock Lake shale member of the Stanton formation, Lansing group, Missouri series, six miles northwest of Garnett, Anderson County, Kansas. ”

“ The anterior margin in R. elegans is essentially straight. Ornamentation consists of sparse, unevenly spaced, coarse tubercles or short striae. In one specimen both bones have small clusters of tubercles near the lateral margins and about 2.0 mm. from the posterior margin. None of these bones has alisphenoids or ridges on the ventral surface, as Stensiö (1921:65, 97) described for Wimania and Axelia. ”

“ Possibly they lived in the lagoon at times of scant rainfall and little runoff, when the salinity of lagoon water approached normal marine values or the fishes may have lived in the streams, and after death were washed into the lagoon. ”

“ Numerous isolated basal plates of the pelvic girdle have revealed details of structure but no information on the orientation. Presumably the basal plates of Synaptotylus had essentially the same orientation as those of other coelacanths (Moy-Thomas, 1937:395) . The most complete basal plate is K. U. no. 788 (see fig. 6B) . The three apophyses diverge anteriorly; the horizontal one is best developed and the dorsal one is least well developed. A median process (Schaeffer, 1952:49) , denticulate on several specimens, articulates with the corresponding process of the opposite plate. ”