The increase of proloculus-diameter in Bolivinoides
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Hofker J. Sr. [1]
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[1] The Hague, Holland
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- Localización: Revista española de micropaleontología, ISSN 0556-655X, Vol. 2, Nº. 2, 1970, págs. 173-182
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
From drill-holes and exactly stratigraphically known outcrops the gens Bolivinoides strigillata-decorata-australis-gigantea was studied from Santonian to Upper Maestrichtian in respect to the diameters of the megalospheric proloculi, Within this gens these diameters very gradually increase. In the end of the evolution irregularities were found which may be due to an attempt to decrease the diameters of the proloculi (the forming of an A,-generation). But this attempt failed obviously. A possible explanation of this attempt, also found at the end of the evolution-series in other groups of Foraminifera, is the decrease of the number of embryons in case of an enlargement of the megalospheric proloculi. This may have caused the extinguishing of the gens.
