Setting up Pangaea: Triassic
Eugeneodontid sharks, previously believed to have become virtually extinct during the great end-Permian extinction event, are here shown to be diverse in the Early Triassic of western Canada. Although the specimens are probably predominantly Olenekian in age, they show an abundance similar to that of the Late Permian of East Greenland. Similar in size and morphology to their Palaeozoic predecessors, this diverse assemblage is seen to have a short duration within the Early Triassic. A number of identifiable dentitions and postcranial skeletal remains suggest the presence of at least two caseodontid species (Caseodus varidentis sp. nov. and Fadenia uroclasmato sp. nov.) and an edestoid (Paredestus bricircum gen. et sp. nov.) Many other specimens recovered from the Lower Triassic Vega-Phroso Siltstone Member (Sulphur Mountain Formation) at Wapiti Lake are too poorly preserved for identification but help demonstrate the major taxonomic problems in eugeneodontid systematics. We discuss the survival of this highly specialized group of ‘sharks’ and comment on their biogeographical distribution across the Permo-Triassic boundary.
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.