Graptolithinia

Fossil plate with Didymograptus murchisoni from the Ordovician.

• Worldwide

The graptolites (font stones) are an extinct genus of similar polyps, colony-forming marine animals, commonly in the gill hole animals ( Hemichrodata ) are classified. In the fossil record are only the living tubes which have a chamber structure. The hemichordate - kinship results from histology and is so narrow that some researchers (such as WN Spasskaya ) the Pterobranchia almost as surviving Graptolit ( h) en conceive. After the discovery of Pterobranchen Cephalodiscus graptolitoides that was found in New Caledonia in great depth, other scientists believe that the graptolites must be filed at the Pterobranchen because the fossilierbaren parts of Cephalodiscus are graptolithoides a graptolites to confusingly similar, while the living organism is an ordinary Pterobranche.

The way of life of graptolites was the beginning of their phylogeny sessile - benthic. In the course of their evolution, developed planktonic species. The construction of the graptolites had a growth along one or more axes. Depending on whether the living chambers ( counters ) were arranged in a single row or multiple rows along the axes, Monograptiden (1 row) Diplograptiden be distinguished ( 2 rows ) or Phyllograptiden ( 4 rows ). The colonies had one or more axes with straight or curved forms of growth.

The potentially unique structural protein ( scleroprotein scaffold protein) this group of animals is the Graptin. It is similar in its construction to the chitin. First described it in 1973 by Roman Kozlowski.

Due to the rapid development of class time, their wide distribution and the macroscopic easily recognizable fossils, the graptolites are excellent index fossils from the Upper Cambrian to the Lower Devonian. Graptolites are preserved mainly in shales ( Graptolithenschiefer ).

System

The graptolites are divided into six orders:

• Dendroidea
• Tuboidea
• Camaroidea
• Stolonoidea
• Crustoidea
• Graptoloidea