

The basipterygia ofAgeneiosus are relatively flat, typically consisting of very 

 porous bone (especially in juveniles), and have a pair of bifurcated prongs anteriorly 

 and a pair of flattened, cartilaginous processes posteriorly (Fig. 27). Typically, each 

 basipterygium also has an anterolateral extension of cartilage, termed the lateral 

 process of the basipteryium (Shelden 1937). The lateral process was thought by 

 Ferraris (1988) to be present in all other doradoids, subject to some variation, and is 

 also found in at least one unrelated family, the Plotosidae; functional variation in 

 the myology and osteology associated with the lateral process was discussed in 

 greater detail by Shelden (1937). Tetranematichthys differs from other species, 

 however, in that the lateral processes are absent or reduced to small cartilaginous 

 plates (Fig. 27c). The pelvic girdle of Tetranematichthys also differs from other 

 ageneiosids in having relatively short anterior processes and in being more solidly 

 ossified. The basipterygium oiA. brevifilis is somewhat broader than in other 

 species, and is also less porous (Fig. 27a). I did not examine skeletal material of 

 large specimens of most other medium-sized species, but I speculate that there is 

 greater ossification with increased size. Ferraris (1988) found that the pelvic girdle 

 oiAuchenipterus has a derived condition among doradoids, characterized by a dorsal 

 convexity of the basipterygia, and with the anterior processes directed obliquely 

 ventrally. Among the ageneiosids examined, some slight variation in curvature of 

 the basipterygia was noted (e.g., slightly more concave in A. atronasus), but no 

 species exhibited the extreme condition found in Auchenipterus; not enough 

 material was examined to determine if there are species-specific differences. 

 Likewise, some species appeared to have more elongate and flattened posterior 

 cartilages, but there were no obvious trends in the shape among species. At present, 

 there is not enough comparative ontogenetic or interspecific information available 

 for doradoids to use the pelvic girdle in phylogenetic comparisons below the generic 

 level. 





