THE OCRURANUS-EOHALOBIA GROUP OF SMALL SHELLY FOSSILS FROM THE LOWER CAMBRIAN OF YUNNAN

Lower Cambrian phosphorite samples from Maotianshan, Yunnan Province, South China, yielded a variety of small shelly fossils. Sclerites of t he second pre-trilobite faunal assemblage of Meishucun, the Paraglobor ilus-Siphogonuchites-Lapworthella association of Nemakit-Daldynian to Tommotian age, were dominant. They comprise previously unknown spine-b earing specimens of Ocruranus finial Liu, 1979, and new morphotypes of Eohalobia diandongensis Jiang, 1982. Well-preserved sclerites reveal a laminated, composite fine structure with marginal, incremental growt h. Each lamella consists of radial series of minute growth elements. T he shells are phosphatically preserved, but micropetrographic evidence from drill-core samples indicates calcium carbonate as primary shell material. In the light of this new evidence, Ocruranus-Eohalobia group fossils are interpreted as parts of coeloscleritophoran scleritomes.