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312 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
20 years ago by the Polish- and Soviet-Mongolian expeditions,
but the first review of their osteology was published only recently
(Barsbold et al., 1990), and most of the long-known
Mongolian cranial specimens still need to be thoroughly studied.
New finds of oviraptorids, including an embryonic skeleton,
have been reported from Mongolia (Norell et al., 1994;
Dashzeveg et al., 1995).
The following description is based on the skull of Oviraptor
sp. (ZPAL MgD-I/95) in the collection of the Institute of Paleobiology,
Polish Academy of Sciences, Warsaw, Poland. This
specimen has been illustrated and interpreted in the context of
broad, primarily functional, comparisons (Osmolska, 1976) but
was never described in detail. Osmolska's (1976) reconstruction
of the oviraptorid palate proved correct except for details
of the median pterygoid contact. Barsbold (1983a, fig. 12) published
an illustration of the similar palate of Oviraptor philoceratops,
which is not accompanied by a description and contains
a misinterpretation of the vomer as the rostral part of the
pterygoid.
Both the premaxilla and maxilla bear sharp tomial edges that
suggest a cutting function of the jaws (Figure 1). The palatal
shelves of the premaxillae and maxillae form an entirely closed
"secondary" palate. The two shelves of each bone remain separated
by a median suture. Dorsal to the shelves, the body of the
premaxilla encloses a spacious sinus. The ventral (palatal) surface
of the premaxillary shelves is overlapped by the maxillary
shelves.
Each maxillary shelf is made of two longitudinal bulges separated
by a shallow groove. The shelf is separated from the tomial
edge by a deep, probably neurovascular, groove that empties
into an opening at the suture with the premaxilla. The
tomial edge is continuous with the lateral wall of the bone,
which overlaps the premaxilla rostrally. The medial wall is
seen in part as a perpendicular stmt, visible in the antorbital
fenestra (Figure 2 A), that rises in the midlength of the bone and
leaves a large maxillary foramen in front. The medial and lateral
walls are both fenestrated and enclose a spacious maxillary
sinus (a part of the antorbital fossa) that extends all the way to
the caudal (jugal) end of the bone (Figure 2A). The maxilla of
Oviraptorphiloceratops has a similar structure (Barsbold et al.,
1990, fig. 10.1 A).
The maxilla is forked caudally (Figure 1). Each palatal shelf
has a prominent knob- or tooth-like caudomedial process. The
two caudomedial processes brace the vomer. Caudolaterally,
the maxilla continues as a palato-jugal wing that articulates
with the palatine, jugal, ectopterygoid, and lacrimal.
The vomer is tightly held between the maxilla and the pterygoid.
The rostral end of the vomer is strongly expanded and
composed of a median knob and lateral wings. The knob is
braced and the wings are overlapped by the caudomedial processes
of the maxilla. The convoluted suture to the pterygoid
suggests a deep interdigitation.
The palatine is composed of the maxillary process, which is
its only prominent rostral process, and the pterygoid (caudal)
qj
pm
mp
plm
1
v fp
A^—p 1 c
W-ec
FIGURE 1.—Reconstruction of the oviraptorid bony palate based on the specimen
ZPAL MgD-I/95. Arrow points to the palatine's ascending wing (invisible
in this view, see Figure 2). Scale bar=10 mm. (ec=ectopterygoid,
fp=postpalatine fenestra, in=intemal naris, ip=interpterygoid vacuity, j=jugal,
l=lacrimal, m=maxilla, mp=tooth-like caudomedial process of maxilla,
plc=choanal conch (pterygoid wing) of palatine, plm=maxillary process of
palatine, pm=premaxilla, pt=pterygoid, ptb=basal wing of pterygoid,
q=quadrate, qj=quadratojugal, t=tomial edges of premaxilla and maxilla, v=
vomer.)
wing, which encloses the choana caudally. The maxillary process
has a triangular ascending wing that forms the lateral wall
of the choana and articulates with the lacrimal dorsally and the
maxilla rostrally (Figure 2B). The pterygoid wing, which is paper-thin
and poorly preserved, is strongly convex-concave dor-