Fig. 3

Change in growth zone dimensions in growing Thamnocephalus larvae. a Growth zone length decreases except after the first molt. This trend is the same when measured by counting cells (b). c The ventral area of the last added segment decreases in Thamnocephalus. d The ventral area of the growth zone decreases, except after the first molt. e The newest segments are longest during early stages. f When measured by counting cells, the length of the newest segment added mimics the linear dimension in e. g Unlike other dimensions, the width of the newly specified Engrailed stripe remains relatively constant during development (growth zone width “A” measure). h A comparison of the average size of the initial growth zone upon hatching (black column) versus the area required to make all additional segments (gray column), where the latter is calculated based on the sum of each newly added segment over the measured course of development. Trunk icon diagram measures represented in each panel and illustrate how ventral area was measured for these comparisons. Bar colors and lines, as in Fig. 2