Extended Data Fig. 3: Late larval stages of P. riniensis.

a–f, AM 5816. g–k, AM 5815. l, m, AM 7539. a, b, Main slab of a large late larva, AM 5816 (no counterslab was found). Photograph overlain with outlines of the anatomical structures identified in this study (a) and interpretive drawing (b). c, Detailed photograph of the head, showing potential preservation of the petaliform plates of the circumoral feeding apparatus (arrowhead) and additional soft tissue structures. d, Detailed photograph of the branchial basket and digestive tract. e, f, Detailed photographs of the posterior trunk, with broken lines showing partial outline of the tail. g, h, Main slab of AM 5815, a small late larva missing a large portion of the snout and posterior half of the trunk. Photograph overlain with outlines of the anatomical structures identified in this study (g) and interpretive drawing (h). i, Photograph of counterslab, which shows posterior extremity of the trunk. j, Detailed photograph of the head, showing arrangement of the branchial arches and positions of the snout structures. k, Detailed photograph of the snout and eyes, showing the small snout structures and otic capsules. l, m, Main slab of AM 7539, a small late larva (counterslab has no anatomically informative trace). Photograph overlain with outlines of the anatomical structures identified in this study (l), and interpretive drawing (m). Scale bars, 2 mm. Definitions of abbreviations are provided in the legends of Figs. 1–3 and ‘Anatomical abbreviations’ in the Methods.