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phyletic lineage

by R. Schroeder, B. Clavel, A. Cherchi, and J. Charollais.

The representatives of the orbitolinid genera Praedictyorbitolina SCHROEDER, CLAVEL et CHAROLLAIS and Dictyorbitolina  CHERCHI et SCHROEDER belong to a monophyletic lineage ranging from the Late Hauterivian to the Earliest Barremian. The establishment of this lineage is based on three evolutionary trends:

  • increase of the size of the tests and change of their morphology,

  • shift of the embryo and development of a subepidermic cellular layer within the deuteroconch,

  • evolution of the network of septula within the marginal zone.

SCHROEDER, R., B. CLAVEL, A. CHERCHI & J. CHAROLLAIS (1999).- Praedictyorbitolina busnardoi n.sp. (Foraminiferida) et évolution de la lignée Praedictyorbitolina - Dictyorbitolina (Hauterivien supérieur - Barrémien basal). Paläontologische Zeitschrift, Stuttgart, 73 (3/4), p. 203-215.


Dictyorbitolina ichnusae
Praedictyorbitolina carthusiana
Praedictyorbitolina claveli
Praedictyorbitolina claveli
Praedictyorbitolina busnardoi

Photos by courtesy of R. Schroeder et alii; sequences from CLAVEL et alii (1995), modified; Hauterivian ammonite zones from HOEDEMAKER, COMPANY et alii (1993); Barremian ammonite zones from VERMEULEN (1998); drawing B. Granier