Primicaris is genus of Cambrian arthropod from the Chengjiang biota of China and the Burgess Shale of Canada. It contains a single described species, P. larvaformis. Description Specimens range from 2.08 to 6.04 mm in length. The undivided subovate-shaped dorsal shield covered the entire body, and wrapped around the front edge of the carapace, forming a doublure structure. The midline of the carapace exhibited thickening. There is a pair of uniramous antennae, as well as ten pairs of biramous limbs. The exopods of these limbs are flagellate and bear setae, with the exopods decreasing in size posteriorly. Taxonomy Its specimens were once thought to be meraspids of Naraoia spinosa. Its phylogenetic position has been described as "problematic". Recent studies have suggested them to be marrellomorphs belonging to the subgroup Acercostraca. See also Arthropod Cambrian explosion Chengjiang biota List of Chengjiang Biota species by phylum References Cambrian animals Maotianshan shales fossils Prehistoric arthropod genera Cambrian genus extinctions