Discorbacea
Encyclopedia
Discorbacea is a superfamily of rotaliid
foraminifera
, with a range extending from the Middle Triassic
to the present, characterized by chambers arranged in a low trochspiral; an umbilical or interiomarginal aperture, with or without supplementary apertures; and a wall structure that is optically radial.
Eight families are currently recognized, further characterized here in.
Two other families were included , the Asterigerinidae and Epistomariidae, which have been removed to the Asterigerinacea
. Some now included families such as the Bagginidae were once defined as a subfamily, the Bagginindae, based on the genus Baggina, in the Discorbidae. As a result the discorbid subfamily Discorbine became the present Discorbidae. The Pegidiidae, originally the rotaliitid subfamily Pegidiinae was removed from the Rotaliacea and added to the Discorbacea as a family. Helenina, a genus in the Discorbinae, became the type for its own family, the Heleninidae. Finally the Eponididae was once included in the Orbitoidacea before being made part of the Discorbacea.
Rotaliida
The Rotaliida are a large and abundant group of foraminiferans. They are primarily oceanic benthos, although some are common in shallower waters such as estuaries. They also include many important fossils, such as nummulites...
foraminifera
Foraminifera
The Foraminifera , or forams for short, are a large group of amoeboid protists which are among the commonest plankton species. They have reticulating pseudopods, fine strands of cytoplasm that branch and merge to form a dynamic net...
, with a range extending from the Middle Triassic
Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided. It spans the time between 245 ± 1.5 Ma and 228 ± 2 Ma...
to the present, characterized by chambers arranged in a low trochspiral; an umbilical or interiomarginal aperture, with or without supplementary apertures; and a wall structure that is optically radial.
Eight families are currently recognized, further characterized here in.
- Discorbidae – Discorbacea in which each chamber is partly divided by an imperforate wall and the umbilical area partly is covered by chamber extensions. Discorbis, Neoeponides
- Bagginidae – Discorbacea with an overall finely perforate test, but imperforate in a part of ventral side Baggina, Cancris
- Eponididae – in which the aperture is interiomarginal and slitlike (or a narrow arch) or areal and cribrate. Eponides, Joanella, Paumotua, Poroeponides
- Heleninidae – in which the primary aperture is interiomarginal and secondary apertures are sutural Helenina.
- MIsissippinidae – have distinct, translucent or opaque bands near the periphery on one or both sides; Mississippina, Stomatorbina
- Pegidiidae – in which coiling is a modified trochospiral, with resorbed early chambers and apertures are open ends of tubes on the ventral side Pegidia
- Rotalinidae – have simple chamber interiors, an umbilicus partly covered by chamber extensions or closed, and an aperutre that is a low interiomarginal arch. Gavellinopsis, Nevconorbina, Rosalina
- Sphaeroidinidae – Discorbacea with strongly overlapping chambers, arranged trochospirally or in different planes; and single slitlike or multiple apertures. Sphaeroidina
Two other families were included , the Asterigerinidae and Epistomariidae, which have been removed to the Asterigerinacea
Asterigerinacea
The Asterigerinacea is a superfamily of foraminifera included in the order Rotaliida.It is a rather new group in terms of its recognition having been proposed by Loeblich and Tappan ca. 1988 and is formed by combining three families previously included in other rotaliid superfamlies...
. Some now included families such as the Bagginidae were once defined as a subfamily, the Bagginindae, based on the genus Baggina, in the Discorbidae. As a result the discorbid subfamily Discorbine became the present Discorbidae. The Pegidiidae, originally the rotaliitid subfamily Pegidiinae was removed from the Rotaliacea and added to the Discorbacea as a family. Helenina, a genus in the Discorbinae, became the type for its own family, the Heleninidae. Finally the Eponididae was once included in the Orbitoidacea before being made part of the Discorbacea.