Figure 2: Presence/absence pattern of the Mesozoic eZHBV_C paleovirus within avian genomes.

Non-neoavian representatives (Gallus, Dendrocygna, Struthio) exhibit the ancestral absence situation, whereas neoavian representatives exhibit the unambiguous presence of the eZHBV_C fragment. In Alcedo, Apus and Chrysolampis, birds that are each phylogenetically nested³⁴ within Neoaves, large and unspecific deletions have led to the secondary loss of almost the complete intron (spanning the paleovirus + flanking sequences). Approximate dates of species divergence^15,32 to the zebra finch (Taeniopygia) are shown in italicized letters. The eZHBV_C presence/absence region is boxed and aligned to the HAS of eZHBV_C. Missing sequence information is denoted as grey dots and numbers denote positions in the full alignment of the eZHBV_C locus (Supplementary Data 1).