Fossil Mooneyes (Teleostei: Hiodontiformes, Hiodontidae) from the Eocene of western North America, with a reassessment of their taxonomy
Eric J. Hilton, Lance Grande, 2008. "Fossil Mooneyes (Teleostei: Hiodontiformes, Hiodontidae) from the Eocene of western North America, with a reassessment of their taxonomy", Fishes and the Break-up of Pangaea, L. Cavin, A. Longbottom, M. Richter
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The skeletal anatomy of fossil hiodontids from western North America is examined based on newly-prepared specimens, including several specimens that were prepared using the acid transfer method and some using the ‘lost fossil’ technique. This study resulted in many new interpretations and clarifications, such as the presence of a curved tubular nasal bone and a posterodorsal spine on the opercle of ‘†Eohiodon’, as found in extant Hiodon. We also further describe the variation of the caudal skeleton that has been known in both fossil and extant Hiodon. For instance, the neural spine of preural one is most often fully developed (as it is in a minority of extant Hiodon specimens), although in some specimens it is rudimentary, as it is in most specimens of living taxa. We review the characters that have been used in recent analyses of relationships of osteoglossomorph fishes. After correcting the descriptions of the fossil taxa, we could find no valid synapomorphies to separate the genus †Eohiodon from the genus Hiodon. Therefore, we conclude that †Eohiodon should be regarded as a synonym of Hiodon.
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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.