sess thin jaws. † Paleopsephurusis not preserved
correctly to see the prearticular. † Chondrosteus
possesses a large, flat prearticular (Watson 1928),
but it is apparently not present in † Peipiaosteus(Liu
& Zhou 1965, Zhou1992).Despite the multiplicity
of outgroup morphologies, the acipenserine prear-
ticular is characteristically reduced.
Character 36. Interhyal-posterior ceratohyal joint
displaced posteriorly-AcipenserinaeThe interhyal-posterior ceratohyal joint occurs on
the posterior half of the interhyal in all acipense-
rines examined (Figure 16d, e). Precise position of
the joint ranges from the posterior edge (chpf, Fig-
ure 16d; e.g.,A. oxyrinchus, A. transmontanus)toa
more central position within the interhyal (Figure
16e; e.g., scaphirhynchines,A. brevirostrum).Figure 21.Lower jaw and prearticular ofPsephurusand representatives ofHusoandAcipenser: The lowerjaw is shown in lateral view to
the left, with the prearticular shown in oral view to the right. Meckel’s cartilage angles posterodorsally tu the jaw joint inPsephurusand
Huso(arrows in a, b), but is straight in acipenserines (c; Character 33). Coincidentally, the flat prearticular of the outgroups (a, b) is
reduced to a thin bone in acipenserines (Character 35) and absent in scaphirhynchines (Character 48).