Acta Palaeontologica Polonica

Evolution of the Jurassic and Cretaceous smooth-walled Lenticulina (Foraminiferida) of Poland

Bronisława Jendryka-Fuglewicz

Acta Palaeontologica Polonica 20 (2), 1975: 99-197

Three developmental phases of the Lenticulina have been distinguished, including (1) Lias, (2) Dogger - Lower Cretaceous and (3) Upper Cretaceous. The phylogenetic changes in the Lenticulina led to a decrease in the number of chambers in the outer whorl with a simultaneous increase in test size, in the degree of involution, and in the diameter of umbilical areas, as well as with a progressive development of the Robulus slit in aperture. The decrease in the number of chambers in outer whorl occurs in independent ways, by: 1 - a decrease, in the geological time, of the number of chambers forming the test and 2 - a decrease in the number of chambers in outer whorl, with a simultaneous increase in the total number of chambers, in the length of spiral and number of whorls. Thirty-one species have been studied and morphotypes distinguished in polymorphic species. Simple statistical methods and microstructural studies were applied. The stratigraphic range of the following, so far confused, species: Lenticulina gottingensis (Bornemann), L. muensteri (Roemer) and L. rotulata Lamarck was established.

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