@article{10272/9075,
year = {2003},
url = {http://hdl.handle.net/10272/9075},
abstract = {Several specimens of Praeradiolites ciryi FLOQUET (1991) and Hippurites quintanalomensis FLOQUET (1991), taken from the Quintanaloma Formation sediments (Upper Campanian-Lower Maastrichtian) 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 0.79 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 13 years. Daily, tidal, monthly and annual cycles have been detected into sclerochronological profiles of these rudist shells. Fortnightly tidal cycles currently show an incomplete number of daily cycles (8-9 for H. quintanalomensis; 10-75 for R 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},
publisher = {Sociedad Geológica de España},
title = {Período vital y ciclos de crecimiento en Praeradiolites ciryi e Hippurites quintanalomensis (Hippuritacea, Bivalvia, Cretácico Superior de Gredilla de Sedano, Norte de Burgos, España)},
title = {Life-span and growth cycles in Praeradiolites ciryi and Hippurites quintanalomensis (Hippuritacea, Bivalvia, Upper

Cretaceous of Gredilla de Sedano, Northern Burgos, Spain)},
author = {Regidor Higuera, I. and García Garmilla, Francisco and Zuluaga, María Cruz and Elorza, Javier},
}