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SMITHSONIAN CONTRIBUTIONS TO PALEOBIOLOGY
FIGURE 1.—Distribution of localities, or groups of localities if situated close to each other, of enantiornithine
birds (solid circles).
later Turgai Strait (Figure 3). Later on, there was no land connection
between Laurasia and Gondwana until the Tithonian,
when the present Gibraltar Strait was already very narrow. It
seems, however, that the present-day Iberian Peninsula was
colonized from other parts of Europe in the Valanginian-Berriasian
because previously it had been an island surrounded by
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FIGURE 2.—Coastlines in the Valanginian-Berriasian, 138 Ma BP (modified
from Smith et al., 1995, reprinted with the permission of Cambridge University
Press). Squares indicate Early Cretaceous enantiornithine localities in Spain
and northeastern China, which at that time were situated on continents divided
by the Turgai Strait. (E=Europe, IP=Indian Peninsula, TS=Turgai Strait.)
more or less wide seas. After the Tithonian, the part of the
Tethys dividing Laurasia and Gondwana was wide again until
the Tertiary. Probably the enantiornithine birds inhabiting these
parts of the earth evolved independently during that time.
The colonization of Gondwana took place in the Bajocian via
the eastern part of North America and Africa (although we do
not have any evidence for the occurrence of the Enantiornithes
in Africa), in view of its land connection with South America
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FIGURE 3.—Coastlines in the Bajocian, 170 Ma BP (modified from Smith et al.,
1995, reprinted with the permission of Cambridge University Press). Arrows
indicate hypothetical directions of dispersal of Enantiornithes.