Bayerische Staatssammlung fur Geologie und Palaontologie and GeoBioCenter

München, Germany

Bayerische Staatssammlung fur Geologie und Palaontologie and GeoBioCenter

München, Germany
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Schneider S.,Bayerische Staatssammlung fur Geologie und Palaontologie and GeoBioCenter | Fursich F.T.,GeoZentrum Nordbayern | Werner W.,Bayerische Staatssammlung fur Geologie und Palaontologie and GeoBioCenter
Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen | Year: 2010

The cardiid Protocardia gigantea sp. nov., which is newly described herein, represents the largest member of this globally distributed genus of shallow-water Mesozoic bivalves. It is found throughout the central Lusitanian Basin (Central Portugal) and may be utilised as a stratigraphie marker for the Kimmeridgian-Tithonian transition in this area, which is confirmed by Sr-isotope data. Its frequent occurrence, large size, and characteristic features make Protocardia gigantea a valuable tool for field stratigraphy. Its taxonomy, systematic position, and ontogenetic as well as intra-population morphological variability are outlined. Possible ancestry in and outside the Lusitanian Basin is discussed, and four other species of Protocardia from the Upper Jurassic of Portugal are taxonomically treated. © 2010 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.


Schneider S.,Bayerische Staatssammlung fur Geologie und Palaontologie and GeoBioCenter | Fursich F.T.,GeoZentrum Nordbayern | Werner W.,Bayerische Staatssammlung fur Geologie und Palaontologie and GeoBioCenter
Palaontologische Zeitschrift | Year: 2011

From its first occurrence in the Middle Triassic to the Late Cretaceous, and thus for almost 200 Ma, Trigonia, type genus of the family Trigoniidae, has been a common constituent of global shallow-marine benthic faunas. The genus is highly over-split at the species level, which hampers sound biostratigraphic, palaeobiogeographic, and palaeoecologic applications. The present study focuses on two closely related species, i. e. Trigonia reticulata Agassiz and Trigonia pseudomeriani Choffat, and illustrates typical problems of species identification in Trigonia. T. reticulata is a well-known representative of the genus with a significant fossil record in Lower Oxfordian to Upper Kimmeridgian strata of western and central Europe, and likely is the ancestor of T. pseudomeriani, which is endemic to the Upper Oxfordian to Lower Kimmeridgian Alcobaça formation of the Lusitanian Basin (central Portugal). In order to effectively display intraspecific variability, digital analyses of a set of metric and non-metric parameters, including outline analysis, were applied to a representative number of specimens from different localities and stages. Originally, these methods were intended to show that both forms are conspecific. Instead, the analysis supports the distinctness of both species based on a very limited number of non-plastic characters. The methods applied can be transferred to other species in Trigonia and may lead to a modern species concept for the genus. Also, they may be successfully applied to other members of the Trigoniinae. © 2010 Springer-Verlag.

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