Figure 9.Left scapulocoracoid ofAcipenser brevirostrum(a) andScaphirhynchus platorynchus(b) in lateral and anterior views: The
ventral scapulocoracoid extends from the coracoid wall (cw) as a flat shelf of cartilage (csh; Character 14) medially in all acipenserids
(arrows pointing left) exceptScaphirhynchus,where it forms a small footprint that flares laterally (arrows pointing right; Character 68).
Acipenserids also possess a broad propterygial fossa (ptgf) at the anterior end of the glenoid ridge where the propterygium (see Charac-
ter 2) pivots on the propterygial bridge (ptb; Character 16). The. propterygial fossa is open anteriorly in all acipenserids exceptScaphi-
rhynchus,where a (thin ridge encircles the fossa anteriorly (Character 67). The anterior face of the scapulocoracoid is L-shaped spanning
the anterior process of the middle region (anp) to the propterygial bridge, then rises dorsally as the cleithral arch (cta) in most acipense-
rids (a), but isexpandedas a broad cleithral wall (ctw)inScaphirhynchus(b; (Character 66).msc= mesocoracoid arch.
martin jones
(Martin Jones)
#1