Extended Data Fig. 5: Hatchling stage of P. riniensis, represented by AM 5813 carrying a yolk sac.

a–c, Main slab. Photograph (a), photograph overlain with outlines of the anatomical structures identified in this study (b) and interpretive drawing (c). d, e, Detailed photographs of the head region in different light angles, highlighting different structures preserved by kaolinite mass. f, Detailed photograph of the branchial region. g, Detailed photograph of the circumoral feeding apparatus. h–j, Counterslab. Photograph (h), interpretive drawing (i) and detailed photograph of the head region (j). Scale bars, 2 mm. Definitions of abbreviations are provided in the legends of Figs. 1–3 and ‘Anatomical abbreviations’ in the Methods.