Eurypterid
Copy of Eurypterus remipes from the Silurian of North America in the State Museum of Natural History Karlsruhe
- Almost worldwide
- Stylonuroidea Diener, 1924
- Eurypteroidea Burmeister, 1843
As sea scorpions, giant scorpions or Eurypteriden ( Eurypterida, gr "wide fins" ) is referred to an extinct group of pine -mouth media ( Chelicerata ) that are incorporated together with the sword tails ( Xiphosura ) in the taxon of Merostomaten ( Merostomata ). This group is the remaining chelicerates, the arachnids (Arachnida ), compared with as a separate class.
Like the sword tails were also Eurypteriden primarily sea creatures and were detected from Ordovician to Permian even there. Then they established themselves in brackish and fresh water, may have some species survive for a short time on the mainland. In 2005, the fossil trace of a movement Hibbertopterus was discovered, which was clearly emerged on land and thus the proof provided that sea scorpions were able to leave the water at least in the short term. With over two meters in body length provide spec some species of this group, such as Eurypterus. the largest known arthropods ( Arthropoda ) ever dar.
The Eurypteriden had a small tank with a little indented head shield ( prosoma ) and an abdomen ( opisthosoma ) with twelve segments. The legs and other limbs put on as in today's spiders and their relatives exclusively on the prosoma, the rearmost pair of legs was transformed into large swimming legs. The front leg members and the chelicerae were equipped with pincer-like structures and teeth, which allowed the detention of the spoils, according to the Eurypteriden can be considered as dangerous predators of that vertebrates.
Very detail -preserved specimens of the genus were already Eurypterus 1898 from dolomite rocks of the Silurian on the island of Saaremaa (Estonia) found. In these animals the finest details could be observed, such as the male and female genital appendages on the second segment of the abdomen. 1995 Eurypteriden were found in the South African Soom Shale, where more details of the muscles and internal organs were visible.