We succinctly list below the revisions we have done in the manuscript since the first submission:
1) We segmented an entirely new gorgonopsian specimen GPIT/RE/7119 showing the basicranium morphology in an ontogenetically more mature specimen. We used this specimen to further validate our observations as well as to give an idea of the variation expected within gorgonopsians.
2) We added many more comparative taxa to support our observations on the evolution of the basicranium in synapsids, including two synchrotron scans of cynodonts (one of them was entirely segmented and we provided a supplementary video), a synchrotron scan of a therocephalian, etc.
3) We re-rendered all the images with VgStudio MAX resulting in much better images plates and figures.
4) We added three new sections in the discussion: “Comparative anatomy of the occiput”, “Comparative anatomy of the basicranium”, and “The evolution of the synapsid basicranial axis: parabasisphenoid, prootic, basioccipital”, and three new figures to better explain and illustrate/demonstrate our results.
5) The occiput of GPIT/RE/7124 was completely re-segmented conforming now to a more typical, expected, gorgonopsian morphology. Namely, the tabulars, the interparietal, and the supraoccipital.
6) The synchrotron tomographic slices of GPIT/RE/7124 were re-reconstructed using a new, more up-to-date and powerful algorithm.
7) The reference list has been substantially expanded with 38 new references.