The head has a pair of simple antennae. The body has 13 tergites, with trunk tergites 2 to 4 having pairs of elongate and uniramous appendages, with appendages absent from the other body segments.[3] The body terminates with paired tail flukes. Unlike waptiids, but similar to Synophalos, the tail flukes lack segmentation.[4] 106 specimens of Plenocaris are known from the Greater Phyllopod bed, where they comprise 0.20% of the community.[5] It has been suggested to be a member of Hymenocarina, which contains numerous other Cambrian bivalved arthropods.[6] Some specimens have been found with sediment within the gut tract, suggesting it was a deposit feeder. The lack of swimming appendages means that swimming was likely primarily accomplished with movement of the trunk and tail fan.[3]
References
^Whittington, Harry B. (1974), "Yohoia Walcott and Plenocaris n. Gen., arthropods from the Burgess Shale, Middle Cambrian, British Columbia", Geological Survey of Canada Bulletin: 1–21
^Hou, Xian-Guang; Bergström, J. (1997), "Arthropods of the Lower Cambrian Chengjiang fauna, southwest China", Fossils & Strata, 45, Scandinavian University Press: 116
^ ab"Plenocaris plena". The Burgess Shale. Royal Ontario Museum. Retrieved 2022-09-08.
