Abstract
AbstractExtant cnidarians are a disparate phylum of non-bilaterians and their diploblastic body plan represents a key step in animal evolution. Anthozoans (anemones, corals) are benthic polyps, while adult medusozoans (jellyfishes) are dominantly pelagic medusae. A sessile polyp is present in both groups and is widely conceived as the ancestral form of their last common ancestor. However, the nature and anatomy of this ancestral polyp, particularly of medusozoans, are controversial, owing to the divergent body plans of both groups in the extant lineages and the rarity of medusozoan soft tissues in the fossil record. Here we redescribe the enigmatic Conicula striata Luo et Hu from the early Cambrian Chengjiang biota, south China, which has previously been interpreted as a polyp, lophophorate or deuterostome. We show that C. striata possessed features of both anthozoans and medusozoans. Its stalked polyp and fully encasing conical, annulated organic skeleton (periderm) are features of medusozoans. However, the gut is partitioned by ∼28 mesenteries, and has a tubular pharynx, resembling anthozoans. Our phylogenetic analysis recovers C. striata as a stem medusozoan, indicating that the enormously diverse medusozoans were derived from an anemone-like ancestor, with the pharynx lost and number of mesenteries reduced prior to the origin of crown group Medusozoa.
Publisher
Cold Spring Harbor Laboratory
Reference169 articles.
1. Stratigraphy, palaeontology, and depositional setting of the Chengjiang Lagerstätte (Lower Cambrian), Yunnan, China;Palaeoworld,2001
2. Brusca RC , Moore W , Shuster SM . 2016. Invertebrates, 3rd edn. Sinauer Associates, Sunderland, Massachusetts.
3. Tentaculate Fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) Interpreted as Primitive Deuterostomes
4. The development and evolution of hydrozoan polyp and colony form
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