Inversidinium caudatum Benson, 1976

Now Palaeotetradinium. Originally Inversidinium, subsequently (and now) Palaeotetradinium.
Holotype: Benson, 1976, pl.13, fig.4-6
Locus typicus: Round Bay, Maryland, U.S.A.
Stratum typicum: Late Maastrichtian-Early Paleocene

Original diagnosis: Benson, 1976, p.218
Bilayered cyst with peridinoid outline. Apex and antapex pointed to slightly rounded, hypotract longer than epitract. Tabulation absent. Periphragm exhibits microreticulate sculpture, both periphragm and endophragm less than 0.5 Ám thick. Sulcus (?) and cingulum (?) reflected by evaginations of periphragm. Endoblast roughly triangular in shape, broader than long, and confined to hypotract. Archeopyle indeterminate.
Dimensions: Holotype: length 54 Ám, width 47 Ám.