English: Figure 1

Cotyledion tylodes Luo & Hu 1999 from the Cambrian Stage 3 Chengjiang fauna (Yunnan, China).

The hemispheric buccal cavity with basal mouth (anterior) and elongate anal papillae (posterior) marked with solid arrows and hollow arrows, respectively. (a), ELI-C-0369, a complete flattened specimen attached by long stalk to exoskeleton of trilobite; note the circular attachment disc (Ad); (b), interpretative drawing; (c), ELI-C-0359A, a laterally compressed specimen attached to gena of a trilobite, showing U-shaped gut with 3-D buccal cavity and enlongate anal tube enclosed inside apertural cavity; (d), interpretative drawing; (e), ELI-C-0359A, counterpart of C, close-up view of the calyx showing the U-shaped gut with buccal cavity and anal papillae; (f), ELI-C-0334A, a flattened specimen showing U-shaped digestive tract; (g), compare to f; (h), ELI-C-0338A, showing mud-filled buccal cavity and anal tube; (i), Compare to h; Scale bars are indicated. Abbreviations: Ad, attachment disc; Ap, anal papilla; Bc, buccal cavity; Cc, the interior cavity of calyx; Es, esophagus; In, intestine; M, mouth; Sc, the central cavity of stalk; St, the distended stomach; Ug, the U-shaped gut.