Tommotiids from the Lower Cambrian of South China

Tommotiids are a geologically short-lived group of early skeletal fossils, most abundant in the Lower Cambrian. Redescriptions of a lapworthellid ( Lapworthella rete Yue, 1987) and a tannuolinid ( Tannuolina zhangwentangi Qian and Bengtson, 1989) from the Jiulaodong Formation, Maidiping, Sichuan, augment previous accounts. Lapworthella rete approaches the L. dentata–L. schodackensis complex, but has a prominent external pattern of polygons that probably represent imprints of epithelial cells. Description of Tannuolina zhangwentangi emphasises ultrastructural features, including the mode of growth, development of canals, and possible epithelial imprints on the interior surfaces. Data on size variation of epithelial imprints in tommotiids are reviewed to try to infer possible variations in genome content of the cells. In addition, poorly preserved lapworthellids ( Lapworthella sp.) are described from the Qiongzhusi Formation, Meishucun, Yunnan.