Hétérochronies du développement sensu Gould chez les foraminifères planctoniques cénomaniens : exemple de néoténie dans le bassin du Western Interior américain

Delphine Desmares, Danièle GROSHENY & Bernard BEAUDOIN

fr Comptes Rendus Palevol 2 (6-7) - Pages 587-595

Published on 30 November 2003

This article is a part of the thematic issue Les chemins de l’Évolution : sur les pas de Steven Jay Gould

Development heterochronies sensu Gould in the Cenomanian planktonic foraminifera: case of neotony in the American Western Interior Basin

During the Cenomanian–Turonian boundary, the anoxic event OAE2 has involved the disappearance of Rotalipora , complex keeled planktonic foraminifera which had conquered deep oceanic water. In the Western Interior basin, the last rotalipores are associated with Anaticinella, morphotypes without keel. The heterochronical relationship between these morphotypes is investigated. The loss of the keel would be a selective advantage enabling them to remain in the surface water, less reached by oceanic anoxia. Thus, two endemic species, only known in the American seaway, are observed: A. multiloculata (Morrow) and A. planoconvexa (Longoria). These species would respectively result by neoteny from R. greenhornensis and R. cushmani.


planktic foraminifera, Cenomanian–Turonian, Western Interior Basin (USA), ontogenetic heterochronies, Oceanic Anoxic Event

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