Fishes and the Break-up of Pangaea: An introduction
There is general agreement that a tight relationship exists between evolutionary histories of living lineages and the shifting geography of the Earth during the Phanerozoic, but how to depict that link has been much disputed in recent decades. The issue is fundamental, as it involves two supposedly-irreconcilable paradigms for how we interpret past and present distributions: the Darwin–Wallace biogeographic paradigm that involves dispersal from centres of origin, and the vicariance paradigm. When dealing with extinct organisms, for which we have only sparse and fragmentary fossil remains, the limit between the two paradigms becomes blurred. Here, all available data about time (stratigraphy) and space (palaeogeography) need to be gathered in order to detect biogeographical signals.
Because of the incompleteness of the fossil record, the analyses may lead to storytelling style descriptions of biogeographic scenarios (phylogenies are often weakly supported, datings are frequently vague and occurrences are sparse). But these scenarios are always open to refutation if new fossils are found and, accordingly, are genuine scientific hypotheses. The Darwin–Wallace biogeographic paradigm and the vicariance paradigm have been described as the extreme points of a pendulum; in this book, examples of relationships between the evolutionary history of fish clades and the break-up of Pangaea are described using approaches that lie between these extreme points of the pendulum.
Figures & Tables
This volume, in honour of Peter L. Forey, is about fishes as palaeobiogeographic indicators in the Mesozoic and Cenozoic. The last 250 million years in the history of Earth have witnessed the break-up of Pangaea, affecting the biogeography of organisms. Fishes occupy almost all freshwater and marine environments, making them a good tool to assess palaeogeographic models.
The volume begins with studies of Triassic chondrichthyans and lungfishes, with reflections on Triassic palaeogeography. Phylogeny and distribution of Late Jurassic neoselachians and basal teleosts are broached, and are followed by five papers about the Cretaceous, dealing with SE Asian sharks, South American ray-finned fishes and coelacanths, European characiforms, and global fish palaeogeography. Then six papers cover Tertiary subjects, such as bony tongues, eels, cypriniforms and coelacanths.
There is generally a good fit between fish phylogenies and the evolution of the palaeogeographical pattern, although a few discrepancies question details of current palaeogeographic models and/or some aspects of fish phylogeny.