Development of the North American Tertiary freshwater fish fauna with a look at parallel trends found in the European record

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Abstract
The Tertiary history of the North American freshwater fish fauna was summarized for comparison with the European fauna. Attention was paid to duration and extinction of taxa, appearance of new taxa, diversity at the generic level and evidence of interchange. For the purpose of comparison, the original Tertiary fauna was judged to be that developed and in place by middle Eocene time in both North America and Europe. The original faunas were quite distinct but had archaic elements in common from the Cretaceous or earliest Tertiary (Paleocene). In North America parts of the Oligocene and Miocene epochs were times of faunal transition and interchange. In reference to the Recent taxa, it was found that most fruitful comparisons could be made by a close look at the faunal components found within selected families like the Cyprinidae which have been studied cladistically. Both Europe and North America received their cyprinids from Asia beginning in the Oligocene. By the end of the Tertiary, cyprinids had evolved into a major segment of the freshwater biota in both areas. However, there was an almost complete lack of interchange between North America and Europe involving cyprinids or any of the other cypriniform families. What was most remarkable for the Tertiary faunas was the absence (with a few noteworthy exceptions) of shared taxa at the generic level. The Tertiary North American freshwater fish fauna had a significant relationship with Asia (probably through separate migrations across Beringia) during the Eocene, Oligocène, early Miocene, Pliocene and Pleistocene. Because the faunas of the two regions (North America and Europe) developed with a number of parallel trends (such as those illustrated by the Cyprinidae) they present a rich subject for discussion.