Extended Data Fig. 1: Literature survey for the presence of CF and GBE in diptera.

Literature-based survey of CF and GBE presence across Diptera, complementing our species sampling. The CF is defined as a deep epithelial fold at the head-trunk boundary during early gastrulation. a, b, Fly families (a) and the species (b) in the order of Diptera for which references could be found. c, Literature references (see supplementary information for corresponding bibliography). d, Reference figure panels with images of embryos during early gastrulation that were used to interpret the presence or absence of GBE and CF. e, Description of image datatype in d. SEM, scanning electron micrographs; DIC, Differential Interference Contrast imaging; in-situ, whole mount micrographs of embryos from RNA in-situ hybridization experiments. f, Interpretation of the presence or absence of GBE and CF based on images in d. Black boxes, presence; hollow boxes, absence; question marks, unclear (see comments below). *, descriptive drawings are a classic resource for the depiction of embryonic development. However, given the potential for subjective interpretations⁷¹, we avoid using these references as definitive evidence for the presence of GBE and/or CF in a given family. **, absence of images during early gastrulation, thus unclear evidence for the CF. Note a late furrow is visible in the image, though the stage is too late to fulfill the definition of the CF. ***, absence of images during early gastrulation, thus unclear evidence for the CF. Although no furrow is visible during late gastrulation, presence of an early transient furrow can not be excluded. ****, absence of images from the anterior region of the embryo, thus unclear evidence for the CF.