03100nas a2200277 4500008004100000022001300041245015600054210006900210260001200279300001200291490000800303520225000311653001302561653001302574653002002587653001402607653001402621653001502635100001602650700002202666700001402688700001902702700001902721700001602740856006602756 2018 eng d a0012825200aEarly evolution of colonial animals (Ediacaran Evolutionary Radiation–Cambrian Evolutionary Radiation–Great Ordovician Biodiversification Interval)0 aEarly evolution of colonial animals Ediacaran Evolutionary Radia c01/2018 a105-1350 v1783 a

Re-evaluation of eumetazoan modular coloniality gives a new perspective to Ediacaran–Ordovician animal diversification. Highly integrated eumetazoan colonies (porpitids [“chondrophorines”], pennatulacean octocorals, anthozoans) prove to be unknown in the Ediacaran. Ediacaran Evolutionary Radiation (EER, new term) fossils include macroscopic and multicellular remains that cannot be compellingly related to any modern group. Claims of eumetazoan coloniality in the Ediacaran are questionable. The subsequent Cambrian Evolutionary Radiation (CER, terminal Ediacaran–late early Cambrian) records appearance and diversification of deep burrowers and a relatively abrupt development of biomineralization. The CER began in a transition zone that spans the Ediacaran–Cambrian boundary and includes the final few million years of the Ediacaran. The early CER has pseudocolonial(?) Corumbella that may be related to some Phanerozoic taxa (conulariids) and records appearance of the first macroscopic biomineralised organisms (Cloudina, Namacalathus, Namapoikea), which may not be eumetazoans. Modular eumetazoans dominate and define many Ordovician and younger habitats (coral, bryozoan, sabellitid reefs; pelagic larvaceans, salps, early–middle Palaeozoic graptolites), but eumetazoan coloniality largely “missed” the EER and CER. All purported Ediacaran–Ordovician porpitids (“chondophorines”) and pennatulaceans are not colonial eumetazoans. Only in the late early Cambrian (late CER) or early middle Cambrian do a few modular colonial eumetazoans first occur as fossils. These include Sphenothallus (available evidence precludes Torellella coloniality), some corals (colonial “coralomorphs”), and lower middle Cambrian graptolithoids. Modular eumetazoan colonies (corals, graptolithoids) in the late early and early middle Cambrian (late Epoch 2–early Epoch 3) and appearance of mid-water predators (cephalopods, euconodonts) and bryozoans in the late Cambrian–earliest Ordovician (late Furongian–early Tremadocian) are the root for the Great Ordovician Biodiversification Interval (GOBI, new term) and diverse later Phanerozoic communities.

10aCambrian10aColonies10aEarly evolution10aEdiacaran10aEumetazoa10aOrdovician1 aLanding, E.1 aAntcliffe, J., B.1 aGeyer, G.1 aKouchinsky, A.1 aBowser, S., S.1 aAndreas, A. uhttp://linkinghub.elsevier.com/retrieve/pii/S0012825217305238