Aktasia irregularis

(Cepek in Cepek & Hay, 1970) Varol, n. comb. Sep 07, 2023

Set number: 622

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10µm

Aktasia irregularis, Late Turonian, Mauritania, West Africa

Final Epithet

Aktasia irregularis (Cepek in Cepek & Hay, 1970) Varol, n. comb.

Basionym

Chiastozygus irregularis Cepek in Cepek & Hay, 1970

Variants

Helicolithus compactus (Bukry, 1969) Varol & Girgis, 1994

Remarks

Large species of Aktasia [>6.0µm] have an asymmetrical cross. Aktasia irregulara is identified from Aktasia compacta by being greater than 6.0µm. Aktasia irregulara is differentiated from Aktasia turonicus (Varol & Girgis, 1994) Varol, n. comb. and Aktasia disgregatus (Stover, 1966) Varol, n. comb. by having an asymmetrical diagonal cross. Aktasia turonicus has an axial cross whilst Aktasia disgregatus has a symmetrical diagonal cross.

References

Bukry, D. 1969. Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles 51 (Protista 2): 1-79.

Cepek, P. & Hay, W.W. 1970. Zonation of the Upper Cretaceous using calcareous Nannoplankton. Palaont. Abh. Abt. B Palaobotanik. 3(3/4): 333-340.

Stover, L. E., 1966. Cretaceous coccoliths and associated nannofossils from France and the Netherlands. Micropaleontology 12(2), 133-167.

Varol, O. & Girgis, M. 1994. New taxa and taxonomy of some Jurassic to Cretaceous calcareous nannofossils. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 192: 221-253.

Taxonomy

Aktasia

Biostratigraphy

Stratigraphic Range

Late Cenomanian - Middle Santonian

Age (Ma)

94.44? - 84.54?

Zone(s)

CC10 - CC16

Holotype

Chiastozygus irregularis Cepek in Cepek & Hay, 1970

Early Campanian

Plymouth Bluff, Tombigbee River, Clay County, Mississippi, USA