There was an error in the supplementary data of Development (2018) 145, dev160945 (doi: 10.1242/dev.160945).

Two panels in Fig. S1 were reproduced from the supplementary material (Fig. S4) of an earlier paper, Development (2017) 144, 4522-4529 (doi: 10.1242/dev.153262).

The panels in Fig. S1 have been replaced. The images in both cases show the same genotype but, for one panel, at a slightly different stage (E10 as opposed to E10.5). The updated file is now available online at

This error does not affect the conclusions of the paper. The authors apologise to readers for this mistake.