Little has been done up to now to use vertebrates to develop biostratigraphic correlation in the Middle and Late Devonian of the western Old Red Sandstone Continent. This is mostly due to the poor documentation of the fauna and the difficulty of dating that which is known. In western North America Middle Devonian vertebrates are more cosmopolitan that those of the Early Devonian which should make them more useful in biostratigraphy; however, a combination of lack of precision in identification and apparent long temporal ranges currently limits their utility. Associated invertebrates allow the Yahatinda Formation (Alberta) and the Denay Limestone (Nevada) to be placed in the Givetian while the upper part of the Grassy Flat Member of the Water Canyon Formation (Utah) and the Spring Mountain Channel (Idaho) are Eifelian. As these localities typically contain faunas that include tuberculate pteraspidids, Asterolepis, Holonema, and osteolepids there is insufficient precision as yet to separate them based on the vertebrates. The Late Devonian is poorly represented by vertebrate faunas other than the reports from the Martin Formation of northern Arizona where a Frasnian fauna a ptyctodonts and arthrodires can be correlated with the Temple Butte Formation northwards. The Elbert, Parting, and Darby formations of Colorado are Famennian in age and contain similar faunas that include Bothriolepis coloradensis, large arthrodires, dipnoans, and osteolepids. In the mid-continent vertebrates are found in the Michigan, Iowa, and Illinois basins. Large collections of chondrichthyans and arthrodires have been made from the Famennian Cleveland Shale in particular and collections are being developed in the correlative Antrim Shale, however, the potential for biostratigraphic correlation has yet to be tapped in this area. In the eastern part of the continent the Catskill delta complex of the Appalachian Basin represents sediments of Famennian age. The lower fauna contains Bothriolepis and Holoptychius commonly together with the rhizodontiform Sauripterus, while the upper fauna contains a more diverse fauna of chondrichthyans and arthrodires together with the osteolepiforms Eusthenodon and Hyneria, the dipnoan Soederberghia, and the tetrapod Hynerpeton. To the north the Escuminac Formation of the Appalachian basin is interpreted as a coastal marine deposit of estuarine origin and is Frasnian in age. Despite having a diverse fauna of agnathans, arthrodires, acanthodians, actinopterygians, and sarcopterygians only three species have been identified elsewhere, Bothriolepis canadensis (from Belgium and Turkey), and Cheirolepis canadensis and Eusthenopteron foordi (from Nevada). However, in each case the identifications are doubtful suggesting that this is another endemic fauna with little applicability to correlation with other faunas. In the Okse Bay Formation from the Frasnian of Ellesmere Island psammosteids, arthrodires and antiarchs, and the rhipidistians Glyptolepis, Holoptychius, and Osteolepis occur. Although the Middle and Late Devonian was a time in which much of the western Old Red Sandstone Continent was divided into separate depositional basins with endemic faunas it does appear that a more detailed analysis of the faunas will yield the data needed for biostratigraphic correlation as is already being shown in western North America.
|Original language||English (US)|
|Number of pages||18|
|Journal||CFS Courier Forschungsinstitut Senckenberg|
|State||Published - Dec 20 2000|
- Middle Devonian
- Upper Devonian
ASJC Scopus subject areas