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New Lower Kimmeridgian ataxioceratin ammonite from the eastern Iberian Chain, Spain: Systematic, biogeographic, and biostratigraphic relevance

100%

Moliner L., Oloriz F.

Acta Palaeontologica Polonica

2010

tom 55

nr 1

New ammonites collected bed−by−bed from the upper part of Ataxioceras hypselocyclum Chronozone deposits in the eastern Iberian Chain are described as Geyericeras gen. nov. The new genus includes microand macroconchiate Ataxioceratinae of small size, with moderate to loose coiling and subpolyplocoid ribs, a character crucial for its identification. Key points for the comparative identification of Geyericeras gen. nov. are: (i) microconchiate Geyericerasshow morphological convergence with evolute specimens of the stratigraphically older genus Schneidia [m]; (ii) contemporary Ataxioceratinae genera such as Ardescia [m, M] and Lithacosphinctes [m, M] did not develop subpolyplocoid ribbing; (iii) smoothing of sculpture combined with short primary ribs are not realized in Geyericeras gen. nov. [M] and can be therefore used to separate the new genus from Ataxioceras[M]; and (iv) smaller shells, and weaker and less dense ribbing with no parabolic structures differentiate Geyericeras gen. nov. [m, M] from Parataxioceras[m, M], as well as the type of subpolyplocoid ribs seen among microconchiate specimens of these two genera. The new species Geyericeras aragoniense sp. nov. is the index and guide fossil for identification of a biohorizon occurring below the first occurrence of the genus Crussoliceras in the eastern Iberian Chain.

Upper Jurassic and Lower Cretaceous sclerites from the Lodz trough of the South-Eastern Slope of the Kujawy Swell

100%

Sztejn J.

Bulletin of the Polish Academy of Sciences. Earth Sciences

1993

tom 41

nr 2

Ograniczanie wyników

1 Acta Palaeontologica Polonica

1 Bulletin of the Polish Academy of Sciences. Earth Sciences

1 Moliner L.

1 Oloriz F.

1 Sztejn J.

1 2010

1 1993

Wyniki wyszukiwania

New Lower Kimmeridgian ataxioceratin ammonite from the eastern Iberian Chain, Spain: Systematic, biogeographic, and biostratigraphic relevance

Upper Jurassic and Lower Cretaceous sclerites from the Lodz trough of the South-Eastern Slope of the Kujawy Swell