Período vital y ciclos de crecimiento en Praeradiolites ciryi e Hippurites quintanalomensis (Hippuritacea, Bivalvia, Cretácico Superior de Gredilla de Sedano, Norte de Burgos, España)
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[1] Universidad del País Vasco/Euskal Herriko Unibertsitatea
Universidad del País Vasco/Euskal Herriko Unibertsitatea
Leioa, España
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- Localización: Geogaceta, ISSN 0213-683X, Nº. 34, 2003, págs. 187-190
- Idioma: español
- Títulos paralelos:
- Life-span and growth cycles in Praeradiolites ciryi and Hippurites quintanalomensis (Hippuritaeea, Bivalvia, Upper Cretaeeous of Gredilla de Sedano, Northern Burgos, Spain)
- Enlaces
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Resumen
Several specimens of Praeradiolites ciryi FLOQUET (1991) and Hippurites quintanalomensis FLOQUET (1991), taken from the Quintanaloma Formation sediments (Upper Campanian-Lower Maastriehtian) at Gredilla de Sedano section (Burgos, Northern Spain) have been studied for determination of their growth velocity, life-span and different types of cyclicity. H. quintanalomensis has a mean growth velocity of 0.30-0.45 cm/year, with a maximum of O. 79 cm/year and having a life-span of 20 years. On the contrary, P. ciryi shows more variable growth velocities, usually between 0.2 and 0.8 cm/year, with a maximum of 1.52 cm/year, varying the life-span from 9 to 73 years. Daily, tidal, monthly and annual cycles have been detected into scleroehronological profiles of these rudist shells. Fortnightly tidal cycles currently show an incomplete number of daily cycles (8-9 for H. quintanalomensis; 10-15 for P. ciryi) represented by an alternance of clear/obscure laminae couples.Monthly cycles enclose a pair of tidal «doublets» and annual cycles (megarhythms) may include up to 25 «doublets» limited by densely-condensed obscure growth-lines. Annual cycles are more easily observable when P. ciryi develops «honeycomb» microstructures. This cellular microstructure tends to disappear coinciding with the wintry limit between years.
