New observations on spicule-like structures from Doushantuo phosphorites at Weng'an, Guizhou Province

Doushantuo phosphorites at Weng'an, Guizhou Province, provide a unique oppo rtunity for the study of early evolution of multicellular organisms, includ ing metazoans. Our light microscope and SEM observations, however, do not s ubstantiate a sponge spicule interpretation of spicular structures. No conv incing axial canals have been seen in the observed spicule population. Inst ead, the coexistence of some monaxonal spicules with clearly diagenetic cry stal fascicles and dumbbells suggest that these monaxons may also be diagen etic in origin. Our preliminary EDS analyses detect no significant silicon in spicule-containing intraclasts (including abiotic clasts and fragments o f sphaeromorphic acritarchs and algal thalli), that contain abundant monaxo nal spicular structures. We, therefore, believe that the evidence for a spo nge spicule interpretation of the Doushantuo spicular structures are at bes t ambiguous at present; these alleged sponge spicules are indistinguishable from coexistent diagenetic crystals.