Abstract
The vertebrate skull is derived from embryonic neural crest and mesoderm. These contributions have been revealed in great detail in one amniote model and to a lesser extent in other taxa. The degree to which patterns of derivation are evolutionary conserved or labile among most lineages nevertheless remains largely unknown. Amphibians are a non‐amniote tetrapod group with a highly derived skull morphology and ontogeny. We employed embryonic transplantations, using GFP‐transgenic axolotls as donors, to document the nature and extent of neural‐crest contribution to the adult osteocranium in this species. Comparisons with chicken and mouse reveal a highly conserved embryonic origin of the tetrapod skull. Conversely, a comparison between axolotl and Xenopus reveals tremendous differences in the origin of skull bones between these two taxa. The unique features of Xenopus may be a consequence of the extensive, posthatching cranial metamorphosis that is characteristic of most anurans. The degree to which the embryonic origin of the vertebrate skull is conserved or labile varies according to lineage and is thus subject to evolutionary change.
Published Version
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