Community structure and composition of the Cambrian Chengjiang biota

Abstract

Based on previously published species data (228 species in over 18 phyla) and field sampling (114 species and 18406 individuals) in the Chengjiang-Haikou-Anning area, we analyzed quantitatively the paleocommunity composition and structure of the Cambrian Chengjiang biota (Cambrian Series 2, eastern Yunnan, China). Arthropods dominate the community both in species diversity (species: 37%) and in abundance (individuals: 51.8%). Priapulids (individuals: 22.6%) and brachiopods (individuals: 16.3%) follow in abundance rank. The arthropod Kunmingella douvillei (26.2%), the priapulid Cricocosmia jinning-ensis (15.4%), and the brachiopod Diandongia pista (11%) are the three most abundant species. Ecological analyses show that the community was dominated by epifaunal organisms (species: 63%, individuals: 68.4%) followed by infaunal organisms (species: 11.9%, individuals: 25.9%), nektobenthic organisms (species: 11.5%, individuals: 2.6%), and pelagic organisms (species: 5.3%, individuals: 3.1%). The diverse feeding strategies, dominated by suspension feeders (species: 35.6%, individuals: 26.1%) and hunter/scavengers (species: 31.1%, individuals: 40.4%), indicate the former existence of a complex food chain and intense competition. Epifaunal vagrant omnivores (28.2%), infaunal vagrant hunter/scavengers (19.8%), epifaunal sessile suspension feeders (17.7%), and epifaunal vagrant hunter/scavengers (15.3%) were the most abundant ecological groups, represented primarily by arthropods, poriferans, priapulids, and brachiopods. Ecological group analyses reveal that the early Cambrian Chengjiang biota is similar in community patterns and functional relations to modern biotas in shallow marine settings.