|
Marrellomorph
Marrellomorpha are an extinct group of arthropods known from the Cambrian to the Early Devonian. They lacked mineralised hard parts, so are only known from Lagerstätte, areas of exceptional preservation, limiting their fossil distribution. The best known member is ''Marrella'', with thousands of specimens found in the Cambrian aged Burgess Shale of Canada. Taxonomy The group is divided up into two major orders, Marrellida and Acercostraca. Marrellida is recognised by the possession of head shields with two or three pairs of elongate spine-like projections, and three attached pairs of uniramous (single-branched) appendages, while Acercostraca generally have large ovoid carapaces that cover the entire upper half of the body, and five pairs of uniramous appendages attached to the head section. Both groups have unbranched Antenna (zoology), antennae and a segmented Tagma (biology), trunk with biramous (divided into two branches) appendages. Recent research has suggested the previou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
