Guangweicaris spinatus: A Fuxianhuiid Arthropod from the Early Cambrian Guanshan Biota of Yunnan Province, China
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The Fuxianhuiids occupy a crucial position in the upper stem-lineage of Euarthropods, and have gained considerable notoriety in recent years, due in large part to the discovery of exceptionally preserved specimens possessing putative nervous tissues, and vascular remains. Most members of this group have been described to possess a head with a wide carapace, covering a hypostome, a pair of antennae, and a pair of specialised post-antennal appendages; a trunk differentiated into a thorax bearing multipodomerous appendages, and a limbless abdomen ending in a telson flanked by a pair of lateral processes. The thorax is divided into the prothorax consisting of a series of anteriorly reduced tergites and the wider opisthothorax bearing pleura. The prothorax is usually covered by the posterior margin of the carapace. Although temporally and geographically restricted to the Early Cambrian (Series 2, Stage 3 to Stage 4), of Yunnan, southwest China, at least seven species of Fuxianhuiid have been unequivocally recognised. The youngest of these is Guangweicaris spinatus, from the Cambrian (Series 2, Stage 4) Guanshan Biota. This species occurs within the Wulongqing Member of the Canglangpu Formation, which outcrops in the vicinity of Kunming. Although known from a large number of specimens (at least 150), this taxon is probably the poorest known of all the Fuxianhuiids.