Factors controlling the distribution of Chitinozoa in the Gleedon chronozone (Wenlockian) of northern Europe

ABSTRACT.- Samples were collected along a chronohorizon defined by the transition between the Wenlockian (Gleedon Chronozone) graptolite zones of Gothograptus nassa and Monograptus ludensis in several northern European localities to evaluate the influence of large scale provincialism and local habitat on the distribution of Chitinozoa. The distribution of Chitinozoa and several environmental parameters based on a number of palaeontological, chemical and physical variables were submitted to Q- and R-mode factor analyses. Provincialism does not seem to influence the distribution of Chitinozoa in the localities considered. The distribution of Conochitina is controlled by physico-chemical factors related to bottom conditions; from this a benthonic habitat can be inferred. The distribution of Linochitina, Ancyrochitina and Sphaerochitina appears to be controlled by biological factors, independent of bottom conditions and thus indicating a planktonic habitat. The increase of Linochitina forms in a stratigraphic column is shown to represent a transgressive trend.