Acanthomeridion serratum from the Cambrian Stage 3 Chengjiang Biota. (a, b) CJHMD 00052a/b respectively, individual with hypostome, ventral plates, and 11 thoracic tergites. (c, d) CJHMD 00053a, showing ventral plate, dorsal sutures, and 11 thoracic tergites. (e–g) YRCP 0016a, showing the ventral plates, and three post-antennal limbs. (h–k) Showing the post-antennal appendages under head, gnathobases of trunk limbs, stick-like exopodites with bristles (black arrows), and endopodites with long spines (white arrows). (f) Micro-CT image of YRCP 0016a; (h, i, k) Micro-CT images of CJHMD 00053a. Abbreviations: ant, antenna; can, post-antennal appendage n beneath head; dbl, doublure; ds, dorsal suture; en, endopodites; ex, exopodites; ey, eye; hs, head shield; hy, hypostome; L, left; lam, lamellae; no, notch; pn, podomere n; R, right; Tn, tergite n; ts, terminal spine; vp, ventral plate.