Polychelida
Proeryon hartmanni
The Polychelida are a partial order of decapods ( Decapoda ). The oldest fossils of these cancers originate from the Upper Triassic.
Features
Characteristic and eponymous feature of the Polychelida are the real scissors on the first four pairs of walking legs. Another autapomorphy is the fusion of ischium and merus in the walking leg pairs two to five. There is a kind of knob or nub at the leading edges of the pleurae of the first abdominal segment. The equivalent where this knob can be hooked, located at the rear edge of the carapace.
System
† Tetrachelidae
† Eryonidae
† Palaeopentachelidae
† Coleiidae
Together with the groups of Achelata were the types of Polychelida the lobster -like ( Palinura ). Due to the paraphyly of this taxon, introduced Gerhard Scholtz and Stefan Richter on the Polychelida.
The Polychelida divided into five families with a total of 93 species, of which only 38 are not extinct the Polychelidae.
- † Coleiidae Van Straelen, 1924
- † Eryonidae De Haan, 1841
- † Palaeopentachelidae Ahyong, 2009
- Polychelidae Wood - Mason, 1875
- † Tetrachelidae Beurlen, 1930