Thylacocephala
Fossil and reconstruction of Ostenocaris cypriformis
- Worldwide
Thylacocephala ( from the Greek θύλακος thylakos "bag" and κεφαλή kephalēs " head") is an extinct genus of bivalve arthropods ( Arthropoda ).
- 3.1 Literature
- 3.2 Notes and references
Features
Thylacocephala were arthropods with a laterally compressed, shield -like armor with a length of 15-250 mm, which enclosed the entire body. Abdominal features as a Telson were not present. The tank was usually an oval or ovoid shape and had the front end of a rostrum and a Sehkerbe, a rear rostrum was possible. The eyes were well developed, usually spherical or teardrop- shaped, with some species also hypertrophied or stalked, and consisted of many small ommatidia. At the head possibly were 5 pairs of limbs and the rear body 8 or more pair that were coming less backwards.
System
The class was developed by Pinna et al. 1982 prepared on the basis of Ostenia cypriformis. They gave it 5 diagnostic features, but no formal definition of the class.
Outer systematics
The Thylacocephala can only be safely assigned to the arthropods ( Arthropoda ). A possible relationship with the crustaceans (Crustacea ), on the basis of the surrounding body armor, could not be clarified until now.
Inside systematics
Schram 1990 divided the members of the class Thylacocephala in two trims: the Concavicarida Briggs & Rolfe, 1983, Thylacocephala with the Sehkerbe overhanging rostrum, and the Conchyliocarida Secrétan, 1983, Thylacocephala of a weakly defined Sehkerbe and rostrum and eyes, which in itself are surface of a large, outstanding " Cephalon bag ".
A distinction is currently 21 genera:
- Ainiktozoon
- Ankitokazocaris
- Atropicaris
- Austriocaris
- Clausocaris
- Concavicaris
- Convexicaris
- Coreocaris
- Dollocaris
- Harry Caris
- Kilianicaris
- Mayrocaris
- Micro Caris
- Ostenocaris
- Paraostenia
- Protozoea
- Pseuderichthus
- Thylacocephalus
- Rugocaris
- Yangzicaris
- Zhenghecaris
The genera Isoxys and Tuzoia probably also belong to the class Thylacocephala.