Discocyclina seunesi

Overview

Discocyclina seunesi is a foraminifer that produced a disc-shaped shell. Fossils left by a single cell help researchers read the chronology of ancient seas. Changes in a tiny body have connected rock layers across regions.^[2][3][1]

Key facts

Even a shell that looks like a smooth disc has very small surface projections. Its broad outline and magnified patterns provide information at different scales. One fossil can be explored both from afar and close up.^[2]

Time and place

It has been studied especially in seas of the late Paleocene Thanetian Stage, roughly 59–56 million years ago. Comparative material from the Haymana–Polatlı Basin in present-day Türkiye, Italy, and Bulgaria is important. These regions preserve different parts of the ancient Tethys Sea’s story.^[1]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

The disc-shaped shell is flat or slightly swollen in the center. Small internal chamber structures are also used in classification and comparison. This organism requires attention from outer outlines to fine internal organization.^[2][1]

Shells of the subspecies Discocyclina seunesi seunesi from Western Carpathian specimens have been reported with diameters of approximately 1.6–5 mm. They resemble small discs with slightly thickened centers.^[13]

Habitat and reproduction

Research in the Haymana–Polatlı Basin identified this foraminifer in shallow-marine sediments deposited as seawater advanced. Above them follow records of organisms from a deeper basin. Reading tiny shells alongside the sequence of rock layers reveals changes in the sea.^[4]

Fossil discovery

A 2001 study described specimens from Türkiye in detail. In 2007, researchers measured and compared internal structures in specimens from several regions to analyze an evolutionary sequence. The research shows gradual changes over time even in organisms bearing the same name.^[2][1]

References

1. Less et al.2007 — Early evolution and stratigraphic subdivision of Tethyan foraminifera
2. Özcan et al.2001 — Late Paleocene foraminifera from the Haymana–Polatlı Basin
3. British Geological Survey — The body and life of foraminifera
4. OpenMETU — Foraminiferal study of the Haymana–Polatlı Basin
5. Systematics, Biostratigraphy and Paleoenvironmental Investigation of Early Ypresian Alveolina Assemblages in the Northern Part of Isparta Angle · Bull. Min. Res. Exp. 164 (2021):183–229
6. ICZN — Palaeontology and Biostratigraphy
7. Alveolina horizons in the Trentinara Formation (Southern Apennines, Italy): Stratigraphic and paleogeographic implications
8. The geographic, environmental and phylogenetic evolution of the Alveolinoidea
9. 1975 — Alveolina ellipsoidalis, Mitteilungen der Bayerischen Staatssammlung für Paläontologie und historische Geologie15:3–18
10. Özcan et al.2001 — Late Paleocene foraminifera from the Haymana–Polatlı Basin
11. British Geological Survey — The body and life of foraminifera
12. Less et al.2007 — Early evolution and stratigraphic subdivision of Tethyan foraminifera
13. Buček·Köhler (2017) — Paleocene reefs of the Western Carpathians

Research questions

Can very small internal changes distinguish intervals of time? Researchers used a trend toward larger initial chambers to identify evolutionary stages within the group. The order in which other species appeared around the Paleocene–Eocene boundary also provides important clues.^[1]

Observation

Examine the disc’s rim and raised center. Alternate between the broad outline and tiny surface projections to discover different kinds of information in the shell.^[2][1]