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272 SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
FIGURE 8.—Comparison of palate structures in ventral view: A, Kiwi, Apteryx sp.; B, Rhea, Rhea americana; C,
Ostrich, Struthio camelus. Probable paths for transferring longitudinal compression forces stippled.
Bpt=basipterygoid process; Mx=maxillary; Pal=palatine; Pmx=premaxillary; Pt=pterygoid; Q=quadrate;
Vbm=vomer. Scale=20 mm.
of their interconnecting point by means of the formation and
gradual elongation of the medial mandibular process. After the
alignment, this hypothetical digastric muscular complex must
have separated from the mandible. Apparently, the recent occipito-mandibular
ligament represents the reduced caudal belly
of the digastric complex.
Conclusion
I would like to comment on the reinterpretation by McDowell
(1978) of the homologies in the avian upper jaw and palate.
It is, of course, tempting to use the kinetic mobility in the skull
Literature Cited
Bock, W.J.
1963. The Cranial Evidence for Ratite Affinities. In Charles G. Sibley, editor,
Proceedings of the XIII International Ornithological Congress,
Ithaca 17-24 1962, 1:39-54.
Buhler, P.
1985. On the Morphology of the Skull of Archaeopteryx. In M.K. Hecht,
editor, The Beginnings of Birds: Proceedings of the International
as a cause of fragmentation of a huge, ancient pterygoid bone
into two; however, many traits in the general arrangement of
the bones (primarily palatine position relative to the choana,
premaxillary, etc.) seem to be consistent with the traditional interpretation
that these two bones represent the reptilian palatine
and pterygoid. The skull in ancient birds almost certainly had
less internal mobility than it does in recent paleognaths, and
such characters as the shape of the lateral rim of the palate or
the pattern of epidermal papillae can hardly be valid. Finally, it
is too difficult to accept McDowell's proposed loss of the maxillary
bone in birds and his consequent thesis that the maxillopalatine
of birds is equivalent to the reptilian palatine.
Archaeopteryx Conference, Eichstdtt, 1984, pages 135-140. Eichstatt:
Freunde des Jura-Museums, Eichstatt.
Cracraft, J.
1974. Phylogeny and Evolution of the Ratite Birds. Ibis, 116:494-521.
de Beer, G.R.
1956. The Evolution of Ratites. Bulletin of the British Museum (Natural
History), Zoology, 4(2):59-70.