Figure25.Gill rakers of representatives of all genera of Acipenseridae: The gill rakers ofHuso(a), primitive polyodontids, and †Chon-
drosteusare elongate. Species ofAcipensertypically possess triangular rakers (b).Scaphirhynchus(c) possesses crenelated rakers with
several paired nubs along the oral edge (Character 63).Pseudoscuphirhynchuskaufmannipossesses pronged rakers with two, orally
pointed tips (Character 58).
temporal as the occipital canal is carried initially by
the posttemporal before entering the lateral extra-
scapulars. Pattern ofthe canals themselves is invar-
iable in acipenseriforms, suggesting that the dermal
patterning changed in Pseudoscaphirhynchus.
Character 57. Jugal is large and lacks a canal process- Pseudoscaphirhynchus
The jugal ofPseudoscaphirhynchusis huge, extend-
ing anteriorly to completely undercut the orbit and
mostofthe olfactory opening, but lacks a canal pro-
cess (see Character 3)enclosing the infraorbital ca-
nal (Figure 3d). The posteromedial jugal is expand-