Rugosa

A copy of the solitary genus Grewingkia from the Ordovician of Indiana ( USA) in three views. Scale 2.0 cm

Worldwide

The Rugosa (also Tetracorallia ) are an extinct order of Hexacorallia who were involved in the Riffbildung from the Middle Ordovician to Late Permian. The German name " Runzelkorallen " ( " rugosen coral " ) is the Latin name, and refers to the wrinkled outer shell (Latin rugosus - wrinkled, rugose ). The term " Tetracorallia " (tetra ( τετρα ) - four) owe the animals their four-jet, axisymmetric blueprint.

Together with the taboo deferred corals ( tabulata ) were the Rugosa the first Riffbildner among the flowers animals. Together with the tabulata and stromatoporoids they formed in the Silurian and Devonian reefs in the largest Paleozoic, the so-called taboo Deferred stromatoporoid reefs.

Approximately 75 percent of all Rugosa were solitary species, the other formed colonies.

Solitary Rugosa be because of their characteristic skeleton as horn corals (not to be confused with the gorgonians, also known as horn corals ) refers. The largest reached a diameter of 14 centimeters and a length of nearly one meter. Colonies could reach four feet in diameter.

It is not to prove whether rugose corals as many of today's coral lived together with symbiotic algae ( zooxanthellae ).

In the Upper Devonian, in the course of repeated strong sea level rises to the mass extinction of Rugosa and tabulata, vanished 90 percent of the shallow-water and 50 percent of the deep water forms. They did not recover it yourself. In the great mass extinction at the Permian / Triassic boundary they died down to a few genera of the order Streptelasmatina how many other creatures finally made ​​.

The increased compared to recent, so alive today, corals number of Wachtumsringe in the skeleton of the Rugosa is an indication for the assumption that the speed of the Earth's rotation in the geological past was higher than in the present. In Devon one days therefore lasted about 22 hours and a year thus had 396 days.

System

The Rugosa be divided by the fine structure of their skeletons into three suborders:

  • Columnariina ( Middle Ordovician - Permian) Spongophyllum
  • Lonsdaleia
  • Cystiphyllum
  • Calceola
  • Goniophyllum
  • Streptelasma
  • Heliophyllum
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