A Diploblastic Radiate Animal at the Dawn of Cambrian Diversification with a Simple Body Plan: Distinct from Cnidaria?
Figure 2
Postembryonic growth of Punctatus.
(A) Hatchling of P. triangulicostalis (Sn62-11) and (B) young P. emeiensis with two annular fringes (kp135). Two distinct body parts are recognized in both species; the embryonic body covered with spines, and the postembryonic body with triangular processes in P. triangulicostalis and with striation in P. emeiensis. (C) Rendering from micro-CT data of a young with four annular fringes (Sn47-96), (D) transverse CT-section at gut level, and (E) median section showing a completely empty body cavity (blastocoel) and small gut. (F) Apical portion of mature P. triangulicostalis (Sn21-38) and (G) a mature P. emeiensis with more than 12 annular fringes (Sn30-03). (H) Clearly demarcated embryonic body at the tip of P. emeiensis (Sn27-06). bc, blastocoel (body cavity); eb, embryonic body; g, gut; mo; mouth; pb, postembryonic body. Scale bars (except C), 0.5 mm.