Figure26. Ventral views of the dermal pectoral girdle of representatives ofHuso, Acipenser,andPseudoscaphirhynchus: The anterome-
dial edge of the clavicles (clv) meet roughly linearly (thin arrows in a, b) in all acipenserids except Pseudoscaphirhynchuswhere they
angle anteriorlytoform a discrete wedge (curved arrows in c; Character59).clt= cleithrum,cvp= clavicle process.
ed, but as an integral portion ofthe bone, not a pro-
cess. This character is predicated on P.kaufmanni
as representative for Pseudoscaphirhynchusdue to
lack of specimens ofother species.
The jugals of Scaphirhynchusand all species of
Acipenserexamined undercut the orbit, but not to
the posterior edge ofthe olfactory opening (Figure
3a,b,c). The anterior process of Husois small and
barely contacts the neurocranium. Relative size isa
qualitative character, but jugals ofall other acipen-
serids examined possess canal processes (Figure 3)
missing in P.kaufmanni.Character58.Gillrakers arepronged-Pseudosca-
phirhynchusGill rakers of Pseudoscaphirhynchus kaufmanni
are split distally into a crescentic edge with paired
pronged tips. These rakers split from a thin base in-
to a curved outer (relative to the branchial arch) tip