A new genus (Triassiphaeodina gen. nov.) and two new species (Medusetta
japonica sp. nov. and Triassiphaeodina niyodoensis sp. nov.) of Late
Triassic (Rhaetian) phaeodarian Radiolaria are described from a
phosphatic nodule found in melange rocks of the Northern Chichibu Belt,
Shikoku, Japan. The Rhaetian age of the nodule and of the phaeodarian
new taxa is based on co-occurring Polycystina Radiolaria, including
Bipedis acrostylus Bragin, Livarella densiporata Kozur and Mostler,
Fontinella primitiva Carter, and Ferresium sp. A of Carter (1993). This
finding shows that phaeodarian Radiolaria were already represented in
Late Triassic oceans, with morphologies similar to those known in the
Late Cretaceous and Cenozoic, from which they have previously been
reported. The new taxa described herein represent the oldest known
phaeodarian fossils.