MORPHOLOGY OF CEPHALIC STRUCTURES IN LATE CRETACEOUS RADIOLARIANS OF THE ORDER NASSELLARIA

Abstract

Eight morphological types of the initial chamber (cephalis) of Late Cretaceous radiolarians of the order Nassellaria are described; seven of them, i.e., Perseus, Napora, Arcanicapsa, Cornutella, Theocoronium, Sciadiocapsa, and Squinabollum, are established for the first time. These types are distinguished by the structure of the cephalic spicule (presence or absence of various spines, incorporation of elements into the cephalic wall, etc.) and the subdivision of the cephalis into upper and lower parts. These data allow one to introduce clarity into the taxonomic position of species of the Late Cretaceous Nassellaria.