Extended Data Fig. 6: Transcriptome age index (TAI) across the ontogeny of eight primary larva-bearing animals.

The TAI values of developmental stages are shown for all individual phylostratum levels. The “young-larval-transcriptome” feature is generally observed across Metazoa, supporting the evolutionarily latter appearance of primary larval stages. For H. discus hannai, although such feature is not evident at the last PS level (ps11), it is evident at older PS levels (e.g., ps4-ps10). E, L and AL represent embryonic, larva and adult-like stages.