Memoir cover 0.tif - Ohio University College of Osteopathic Medicine

18 SOCIETY OF VERTEBRATE PALEONTOLOGY, MEMOIR 3
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FIGURE 12. Plateosaurus engelhardti, facial skeleton. A, reconstruction
of snout in left lateral view. B, same in ventral view. C, right nasal
of AMNH 6810 in ventromedial view. D, stereophotographs and interpretive
drawing of right maxilla, lacrimal, and palatine of AMNH 6810
in dorsal and somewhat medial view. The nasal recess shown in C caps
the hiatus in D. A,B modified after Galton (1990).
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jUY neurovas int
FIGURE 11. Iguanodon atherjieldensis, facial skeleton. A, Snout in
left lateral view (modified from Noman,1986). B, left maxilla, jugal,
lacrimal, and prefrontal of BMNH R5764 in medial view. Arrow shows
the course of the nasolacrimal duct.
tending into the premaxillae as well. These foramina and canals
likely conveyed branches of the maxillary nerve and accompanying
vessels. Their positions dorsal or dorsolateral to the
putative muscular fossa on the palatine are consistent with the
dorsal pterygoideus muscle being restricted to the floor of the
antorbital cavity.
Dinosauria-Among Omithodira, comparable data are abundant
for dinosaurs, but less so for other taxa. Good material is
available for the basal members of many of the major clades
of Ornithischia (Sereno, 1986). The basal omithischian Leso-
thesaurus diagnosticus (Weishampel and Witmer, 1990a; Sereno,
1991a) provides information on both the existence and
position of a dorsal pterygoideus and the course of the maxillary
neurovasculature. The dorsal surface of the palatine
(BMNH R8501, RUB17) has a well developed excavation extending
rostrally up to the lateral aspect of the choana (Fig. 7C,
D). This excavation is here interpreted as a muscular fossa and
is bounded rostrally .by a strong ridge that extends from the
maxillary contact (where it borders the choana) rostrodorsomedially
to the contact with the vomer. The palatine (BMNH
RUB17) has an additional deep fossa rostral to this ridge and
dorsomedial to the choana and directly opposite the internal
antorbital fenestra that must be associated with either the nasal
or antorbital cavity. The muscular fossa is restricted to the caudoventral
portion of the antorbital cavity. The proximity of the
ridge bordering the fossa to the medial edge of the lacrimoprefrontal
wall (BMNH R8501) suggests that the postnasal fenestra
was narrow in this area and would make rostral passage of a
muscular slip unlikely. The course of the maxillary neurovas-