Cretaceous Research 22,
3, 333-351 (2001) Kaim, A. Abstract. The
Valanginian fossil assemblages at Wšwa³ in central Poland are dominated by
juvenile gastropods with planktotrophic, mostly pelagic larvae, thus largely
independent of local bottom environment in their distribution. The
gastropod-dominated associations show a species turnover pattern surprisingly
consisting with eustatic cycle and changes in biogeographic provincionalism,
strongly expressed also in the distribution of ammonites. The Valanginian sea
expanded to central Poland from the north, bringing cold waters with boreal
faunas and at the deepening sea bottom the diversity of benthonic
macroorganisms decreased. During the early Late Valanginian highstand, the
seaway connecting north European with the Carpathian ocean expanded enough to
allow migration the Tethys organisms to central Poland. In the late Late
Valanginian this eustatic trend reversed and Boreal faunas replaced again
those from the Tethys. The isotope record in benthonic foraminifer tests
suggests that despite the sea level changes the bottom water temperatures
remained relatively stable. |