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NUMBER 89 317
cidae, Anhimidae, Columbidae, Sagittariidae, Strigiformes,
and Trogonidae (Figure 4). The pterygoid of the Procellariidae
and Pelecanoididae has a rostral wing that extends to the rostral
end of the bone and articulates only caudally with the basipterygoid
process. The basal articular surface is least set off
from the shaft of the pterygoid in the Cathartidae.
The basal process of the pterygoid is poorly developed in Archaeopteryx,
and the structure of the basipterygoid articulation
remains unknown in Gobipteryx, which makes the phylogenetic
significance of this character somewhat ambiguous. Because
the basal process of the oviraptorids (and probably in the caenagnathids,
the basipterygoid articulation of which is very similar
to that of oviraptorids) is distinctly better developed than it
is in Archaeopteryx, it is interpreted herein as another possible
synapomorphy linking the oviraptorosaurs to the omithurines.
The quadrate ramus of the pterygoid is closely appressed on
the braincase in the oviraptorids, omithomimosaurs, and theriz­
inosauroids. The basipterygoid process is virtually absent in the
oviraptorosaurs, which have the articular surface of the pterygoid
developed directly on the cranial base (Sues, 1997, fig. 3),
and the same seems to be tme of the therizinosauroids (Clark et
al., 1994:20). The identification of the basipterygoid processes
in the omithomimosaurs remains uncertain. Their quadrate
wing of the pterygoid has a prominent medial process that
seems to abut the cranial base at the level of mandibular articulation
(i.e., behind the sphenoid capsule). This is clearly visible
in an undescribed skull (ROM 851) of Omithomimus edmontonicus
(pers. obs.). The apparent basal process of the pterygoid
was left uninterpreted in Gallimimus bullatus Osmolska et
al. (Osmolska et al., 1972, fig. 2; Barsbold and Osmolska,
1990, fig. 8.1), and the basipterygoid articulation was identified
farther rostrally on the sphenoid capsule, a contact that is
unlike a theropodan basipterygoid articulation and may have
arisen as a result of the transverse expansion of the capsule.
FIGURE 4.—The pterygoid in various neognathous birds, medioventral view: A, Turnix varia (Latham); B, Pelecanoides
urinatrix (Gmelin); C, Procellaria aequinoctalis Linnaeus; D, Coragyps atratus (Bechstein); E, Sagittarius
serpentarius (Miller); F, Anhima cornuta (Linnaeus); G, Chauna torquata (Oken); H, Columba fasciata
Say; I, Philomachus pugnax (Linnaeus); J, Vanellus vanellus (Linnaeus); K, Trogon rufus Gmelin; L, Strix aluco
Linnaeus. In B-E, the length of the basal articular surface on the pterygoid (indicated by "b" in D,E) is much
greater than the rostrocaudal width of the basipterygoid process. (b=basal process, p=palatine articular surface,
q=quadrate articular surface, w=rostrobasal wing.)