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and Australia by way of the Antarctic (Figure 4). A second
wave of colonization of North America was possible later, independent
of the colonization of Gondwana, in the Early Cretaceous
(Valanginian).
In Chiappe's (1991) opinion, the Enantiornithes evolved in
Gondwana, whereas Zhou (1995a) claims that Laurasia was
their cradle. In Chiappe's (1991) conception, the whole process
of colonization of the earth ran in the opposite direction, which,
from the viewpoint of the history of continents, also is possible.
If the Enantiornithes separated in the Bajocian, they theoretically
could have originated anywhere on the earth. Vorona berivotrensis
Forster et al. (1996), discovered in Madagascar and considered
to be a sister group of the Enantiornithes, speaks in
favor of Chiappe's conception. On the other hand, the age of the
remains and the differentiation of the forms from Laurasia seem
to support Zhou's (1995a) opinion, and this is the reason for
adopting my present course of reasoning. No matter which of
these two theories is right, the history of continents indicates
that the subclass Enantiornithes evolved in the Middle Jurassic,
more than 25 million years before Archaeopteryx.
The genera Nanantius and Enantiornis were first described
from Gondwana in the Albian of Australia (Molnar, 1986) and
the Maastrichtian of South America (Walker, 1981), respectively.
The acceptance of land dispersal for the Enantiornithes
against a background of the history of continents raises doubts
that the Late Cretaceous remains mentioned from Uzbekistan
and the Gobi Desert (Nesov and Panteleev, 1993; Kurochkin,
1995a, 1996) could actually belong to these genera. Even if
their flight abilities were considerably greater than in the Early
Cretaceous Enantiornithes, at that time the oceans between all
Bocheriski, Z.
1997("1996"). Enantiornithes—dominuj^ca grupa ladowych ptakow kredowych
[Enantiornithes—A Dominant Group of the Cretaceaous Terrestrial
Birds]. Przegl^d Zoologiczny, 40(3^1): 175-184, 4 figures. [In Polish,
with English summary. Date on title pages is 1996; actually published
in 1997.]
Chatterjee, S.
1991. Cranial Anatomy and Relationships of a New Triassic Bird from
Texas. Philosophical Transactions of the Royal Society of London,
Biological Sciences, 332(1265):277-342, 40 figures. London: The
Royal Society.
1994. Protoavis from the Triassic of Texas: The Oldest Bird. [Abstract.]
Journal fur Ornithologie, 135(3):330.
Chiappe, L.M.
1991. Cretaceous Birds of Latin America. Cretaceous Research,
12:55-63.
1993. Enantiornithine (Aves) Tarsometatarsi from the Cretaceous Lecho
Formation of Northwestern Argentina. American Museum Novitates,
3083: 27 pages, 13 figures.
Dong, Zhi-Ming
1993. A Lower Cretaceous Enantiornithine Bird from the Ordos Basin of
Inner Mongolia, People's Republic of China. Canadian Journal of
Literature Cited
FIGURE 4.—Coastlines in the Albian, 105 Ma BP (modified from Smith et al.,
1995, reprinted with the permission of Cambridge University Press). The star
indicates the Albian locality of Nanantius in Queensland. Arrow indicates the
latest possibility of colonization of Australia, assuming that the Antarctic was
colonized earlier (not later than in the Tithonian). (IP=Indian Peninsula.)
the places mentioned above were too wide to permit crossing
(see Figure 4 and Rich, 1976). It also is doubtful that the genus
Nanantius would have survived for 25 million years (i.e., from
the Albian to the Campanian) or even longer.
Earth Sciences, 30:2177-2179.
Forster, C.A., L.M. Chiappe, D.W. Krause, and S.D. Sampson
1996. The First Cretaceous Bird from Madagascar. Nature, 382:532-534,
4 figures.
Haq, B.W., and F.W.B. Van Eysinga
1987. Geological Time Table. Fourth edition. Amsterdam: Elsevier Science
Publishers. [Wall plate.]
Hou, L.
1995. Morphological Comparisons between Confuciusomis and Archaeopteryx.
In A. Sun and Y. Wang, editors, Sixth Symposium on Mesozoic
Terrestrial Ecosystems and Biota; Short Papers, pages
193-202. Beijing: China Ocean Press.
Kurochkin, E.N.
1995a. The Assemblage of the Cretaceous Birds in Asia. In A. Sun and Y.
Wang, editors, Sixth Symposium on Mesozoic Terrestrial Ecosystems
and Biota; Short Papers, pages 203-208, 3 figures. Beijing:
China Ocean Press.
1995b. Synopsis of Mesozoic Birds and Early Evolution of Class Aves. Archaeopteryx,
13:47-66.
1996. A New Enantiornithid of the Mongolian Late Cretaceous, and a
General Appraisal of the Infraclass Enantiornithes (Aves). 50
pages, 13 figures, 3 plates. Moscow: Russian Academy of Sciences,