Extended Data Fig. 1: Comparison of the specimens of P. riniensis to the same scale in reverse ontogenetic order.

a, b, An adult (AM 5750), photograph (a) and interpretive drawing (b). c, d, A juvenile (AM 7538), photograph (c) and interpretive drawing (d). e, f, A large late larva (AM 5816), photograph (e) and interpretive drawing (f). g, h, A small late larva (AM 5815), photograph (g) and interpretive drawing (h). i, j, A small late larva (AM 7539), photograph (i) and interpretive drawing (j). k, l, A large early larva (AM 5817), photograph (k) and interpretive drawing (l). m, n, A small early larva (AM 5814), photograph (m) and interpretive drawing (n). o, p, A hatchling (AM 5813), photograph (o) and interpretive drawing (p). Scale bar, 2 mm. q, Reconstruction of three individuals of Priscomyzon, each representing a different ontogenetic stage. Clockwise from the right: a hatchling carrying a yolk sac (based on AM 5813), tucked in the meadow of the charophyte Octochara crassa; a juvenile (based on AM 7538), attached to the substrate in the foreground; and an adult (based on AM 5750), looming over the other individuals and showing its feeding apparatus. In the background, a school of the coelacanth Selenichthys kowiensis swim above the charophyte meadow. Artwork by K.T.