Figure 4
Trilobite protaspides and meraspides from Cambrian Stage 5 Duyun fauna.
(a), (b) genus and species indet. 1 showing paired anterior fixigenal spines and mid-fixigenal spines (arrowed), posterior fixigenal spines and fine lines on the doublure: (a) YKLP 12060, dorsal view; (b) YKLP 12061, ventral view. (c), (d) genus and species indet. 2, dorsal shield tetragonal in outline with short and broad posterior fixigenal spines: (c) YKLP 12062, dorsal view, showing deep fossulae; (d) YKLP 12063, dorsal view. (e), (f) genus and species indet. 3 with sagittal glabellar furrow (white arrowed) and occipital cut (black arrowed): (e) YKLP 12064, oblique dorsal view; (f) YKLP 12065, laterodorsal view, showing paired anterior fixigenal and mid-fixigenal spines. (g)–(l) corynexochid exoskeletons: (g) YKLP 12066, protaspis of stage 1 (P1), dorsal view, showing moderately elevated glabella, deep fossulae and axial furrows, inflate occipital ring and two pairs of protopygidial marginal spines. (h) YKLP 12067, protaspis of stage 2 (P2), dorsal view, showing occipital cut (arrowed) and one axial ring of protopygidium; (i) YKLP 12068, ventral view, showing well developed doublure and survived hypostome; (j) YKLP 12069, late developmental stage protaspis, oblique dorsal view, showing eye ridges and protopygigium with at least two axial rings; (k) YKLP 12070, meraspid cephalon, dorsal view, showing moderately convax axis with the anterior lobe expanded remarkably. (l) YKLP 12071, late meraspid cranidium fused to an echinoderm sclerite, oblique dorsal view. All scale bars, 200 µm.
