Extended Data Fig. 8: Comparison of anatomical traits preserved in the specimens of Palaeozoic stem lamprey described in this Article.

a, Modern decay series of ammocoetes and adult lampreys, after a previous publication²⁰. Codes for these reference decay series are as follows. Yellow, pristine; orange, decaying; red, onset of loss; terminal point, complete loss. The x axis shows number of days, whereas y axis ranks decay stages. For each fossil specimen (b–p), bars shown in original colours (yellow, orange, and red) represent characters preserved in the specimen; 50% transparent (brown) bars represent characters preserved in the specimen but in a different form than in the modern reference; grey bars represent characters missing in the specimen; no bars shown denotes that, in principle, characters cannot be assessed in the specimen (for example, ‘slanting gill openings’ cannot be determined in dorsoventrally compressed specimens, whereas ‘gill symmetry’ cannot be assessed in transversally compressed specimens). b–i, Priscomyzon riniensis. b, AM 5750, representing the adult stage. c, AM 7538, representing the juvenile stage. d–f, AM 5816 (d), AM 5815 (e), and AM 7539 (f), all representing the late larval stage. g, h, AM 5817 (g) and AM 5814 (h), representing the early larval stage. i, AM 5813, representing the hatchling stage. j, k, Pipiscius zangerli. ROM 56679 (j) and FMNH PF16082 (k), both representing the hatchling stage. l, Mayomyzon pieckoensis. FMNH PF8167, representing the late larval stage. m–q, Hardistiella montanensis. m, CM 4505, representing the late larval stage. n, ROM 78122, representing the juvenile stage. o–q, CM 63079 (o), UMPC 10210 (p), and UMPC 7696 (q), all representing the adult stage. Interpretive drawings in b–q are not to scale.