ペルム紀放散虫Albaillellariaのニ形性

Dimorphic pairs occurred in Permian radiolarians which are normal form of domiant numbers called the N type and deformed shell characterized by an swollen of apical cone called the S type. Dimorphic pairs appeared in Albaillellaria of a bilaterally symmetry and covered by imperforated shell wall, such as Albaillella, Pseudoalbaillella, Follicucullus and Neoalbaillella.
Dimorphic pairs were examined in bedded chert sequences, and within a single bed of chert with respect to radiolarian blooming of the Permian time . In general occurrence rate of the S type from the single bed of the bedded chert, is about 3% of total number of species, however the S type of Pseudoalbaillella ornata of which the species is the biggest and mostly ornamented shell among species of Pseudoalbaillella as well as other Albaillellaria exceeds 20%.