Primicaris

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.

Primicaris Temporal range: Cambrian Cambrian Stage 3–Miaolingian PreꞒ Ꞓ O S D C P T J K Pg N
Reconstruction of Primicaris
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	†Marrellomorpha
Order:	†Acercostraca
Genus:	†Primicaris Zhang et al., 2003
Species:	†P. larvaformis
Binomial name
†Primicaris larvaformis Zhang et al., 2003

Description

Diagrammatic reconstruction of Primicaris

Specimens range from 2.08 to 6.04 millimetres (3⁄32 to 1⁄4 in) in length, and 1.50 and 4.20 millimetres (1⁄16 and 5⁄32 in) in maximum width. 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 slender uniramous segmented 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. The endopods are poorly preserved.^[1]

Taxonomy

Its specimens were once thought to be meraspids of Naraoia spinosa.^[1] Although their phylogenetic position has been described as "problematic",^[2] recent studies have suggested them to be marrellomorphs belonging to the subgroup Acercostraca.^[3][4]

See also

• Paleontology portal
• Arthropods portal

• Arthropod
• Cambrian explosion
• List of Chengjiang Biota species by phylum
• Paleobiota of the Burgess Shale