New observations on spiculelike structures from Doushantuo phosphorites at Weng’an, Guizhou Province

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Doushantuo phosphorites at Weng’an, Guizhou Province, provide a unique opportunity for the study of early evolution of multicellular organisms, including metazoans. Our light microscope and SEM observations, however, do not substantiate a sponge spicule interpretation of spicular structures. No convincing axial canals have been seen in the observed spicule population. Instead, the coexistence of some monaxonal spicules with clearly diagenetic crystal fascicles and dumbbells suggest that these monaxons may also be diagenetic in origin. Our preliminary EDS analyses detect no significant silicon in spicule-containing intraclasts (including abiotic clasts and fragments of sphaeromorphic acritarchs and algal thalli), that contain abundant monaxonal spicular structures. We, therefore, believe that the evidence for a sponge spicule interpretation of the Doushantuo spicular structures are at best ambiguous at present; these alleged sponge spicules are indistinguishable from coexistent diagenetic crystals.