Nummulites

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Nummulites
Heterostegina depressa

Heterostegina depressa

Systematics
without rank: Retaria
without rank: Foraminifera (Foraminifera)
without rank: Globothalamea
without rank: Rotaliida
Superfamily : Rotaliacea
Family : Nummulites
Scientific name
Nummulitidae
de Blainville , 1827
Numulite lime. The housings show the typical spiral-shaped, round shape and the internal structure, which is enclosed by partition walls (image section 3 × 4 cm)

Nummulites (Nummulitidae), also popularly known as "coin (s) stones", are a family of circular or elliptically shaped unicellular organisms from the group of Foraminifera (Foraminifera), in the order of the Rotaliida .

description

The nummulites are large foraminifera that can typically reach 1 to 2 centimeters in diameter.

The largest recent species reaches up to 13 centimeters ( Cycloclypeus carpenteri ), fossil Nummulitidae reached a size of up to 16 centimeters. The housings are biconvex discs, multi-chambered and mostly plane-spiral. The chamber walls form a complex canal system with the keel, which is filled with cytoplasm .

Way of life

Nummulitidae belong to the so-called large foraminifera, live in warm shallow seas and harbor bare diatoms as endosymbionts ( zooxanthellae ). It is believed that their ontogeny lasts over 100 years.

Systematics

The circular shape of the case gave the family its name, from the Latin nummulus "little coin".

Today the group comprises only 11 species in 8 genera:

Extinct genera (selection):

Fossil nummulites

The family appears fossil in the uppermost Cretaceous and experienced its heyday in the early Tertiary , here especially in the Tethys .

In the Paleogene (Old Tertiary) the group was particularly rich in species and formed the so-called Nummulitenkalke. The genera Assilina (†) and Nummulites are index fossils of the Tertiary .

In the geological past, the calcareous shells of the nummulites could accumulate in such large masses after their death that they became rock-forming, as was the case with the nummulite limestone from the Old Tertiary. Quarries nearby provided the blocks of Eocene gray-yellow, fine-fossilized and gray, coarse-fossilized nummulite limestone, with which approximately 60% of the pyramids of Giza were built. The rocky subsoil also consists of very solid Nummulite limestone. When Herodotus visited Egypt, he thought the nummulites were petrified lentils , leftovers from the meals of the pyramid workers. This interpretation as " stone lenses " (lens stones) is also documented in Central Europe, for example in Guttaring in Carinthia, where you can easily find innumerable nummulites in the clay soil and a so-called field of stone lenses is designated.

In the foothills of the Alps in Bavaria, Nummulite limestone such as the so-called Enzenau marble was used for historical buildings.

swell

  • Dietrich and Rosemarie Klemm : Stones and Quarries in Ancient Egypt , Springer Verlag Berlin, 1992, ISBN 3-540-54685-5 .
  • Volker Storch, Ulrich Welsch: Short textbook of zoology . 8th edition, Spektrum Akademischer Verlag, 2004, ISBN 3-8274-1399-0
  • Johann Hohenegger, Elza Yordanova and Akio Hatta: Remarks on West Pacific Nummulitidae (Foraminifera) . The Journal of Foraminiferal Research, 30 (1), pp. 3-28

Individual evidence

  1. ↑ a b c d Rudolf Röttger: Dictionary of Protozoology In: Protozoological Monographs, Vol. 2, 2001, p. 155, ISBN 3-8265-8599-2
  2. ^ Dietrich and Rosemarie Klemm , Stones and Quarries in Ancient Egypt , Springer Verlag Berlin, 1992, pp. 53–59, ISBN 3-540-54685-5
  3. ↑ Trixler, Frank: Enzenauer quarry . In: Fossilien 6, No. 1, 1989, pp. 8-9. ISSN  0175-5021

Web links

Commons : Nummulites  - collection of images, videos and audio files