Apr 28, 2003 - clathrata occurs at the south-central coast of Laurussia (western I central Europe), Armorica and Bohemia, and Conocardium gogoense is ...
Cour. Forsch.-Inst. Senckenberg
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242
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4 Figs., 4 Pis.
51-69
I Frankfurt a. M., 28.04.2003
Biogeographical distribution patterns in Mid- and Late Palaeozoic Conocardioida (Mollusca: Rostroconchia) With 4 figures and 4 plates
Nicole S. ROGALLA & Michael R.W. AMLER
Abstract In a preliminary study the geographical occurrences and distribution of some rostroconch taxa of the order Conocardioida throughout the centrall equatorial continents and oceans of four distinct diversity acmes in the middle Early Devonian, the late Middle Devonian, the late Early Carboniferous and the middle Late Carboniferous are shown. These middle and late Palaeozoic rostroconchs show distinct distribution patterns which enable aseparation of provisional biogeographical provinces. During the middle Early Devonian, Conocardium attenuatum and C. nevadensis as we il as Hippocardia cunea. are restricted to the south-western coast of Laurussia (eastern North America), whereas Hippocardia bohemica, H. ornatissima, H. abrupta and COllocardium prunum are typical for the Bohemian Terrane.
In the late Middle Devonian (and probably early Late Devonian) Hippocardia cunea, H. monroica and Conocardium pseudobellum characterize west-central Laurussia. Biga/ea clathrata occurs at the south-central coast of Laurussia (western I central Europe), Armorica and Bohemia, and Conocardium gogoense is restricted to Australia. By the closure of the Variscan Ocean in the late Early Carboniferous, a distinct separation of southern Laurussia is visible in the restriction of Aphelacardia alternistriata, Hippocardia herricki and Baiosoma cucullata to south-western Laurussia (eastern North America), whereas Conocardium alae/orme, C. elongatum, Hippocardia /usiforme and H. hibernica are confined to south-central Laurussia (western I central Europe); some of wh ich (Conocardium alae/orme, Hippocardia hibernica) mayaiso have occurred at the south-easlern coast of Laurussia (Russia, Ukraine) . Aseparate real m existed at the western coast of Laurussia, indicated by Arceodomus glabrata and A. prolata. After the closure of the Palaeo-Tethys, two separate realms persisled, characterized by Apotocardium lanterna and some minute hippocardiids in western Laurussia and Conocardium orien.tale, C. ustritskyi and Arceodomus snjalkovi in eastern Laurussia. The distribution maps also reveal particular information gaps which include Morocco, South America, South-East Asia, China and Australia but, although far beyond of being complete, our current data pool of conocardioids proves advanced rostroconchs to be important taxa for discriminating biogeographieal provinces in the Middle and Late Palaeozoic. Based on the continuous addition of data 10 our data base, the distribution maps will reveal improved and modified information. Keywords: Rostroconchia, Conocardioida, Biogeography, Devonian, Carboniferous, Laurussia, Palaeo-Tethys
Introduction Some 30 years ago, peculiar molluscs of uncommon bivalve shape and unknown systematic position were formally established as the class Roslroconchia (POJETA et a1. 1972). Few years later, the pioneering monograph on
roslroconch molluscs by POJETA & RUNNEGAR (1976) established a first systematic arrangement of taxa forrnerly classified as unusual bivalves and arthropods, then based on re-interpreted morphology and evolutionary history. Subsequently, ribeiriids and hippocardiids have aroused special interest because of their peculiar morphology. But
Authors' address: Lnstitut für Geologie und Paläontologie am Fachbereich Geowissenschaften der Philipps-Universität Marburg, Abt. Invertebraten-
Paläon tolog ie, Hans-Meerwein Straße; 0-35032 Marburg; Germany
