Vertebrates are one of the few metazoan taxa, which display a well-corroborated phylogenetic pattern, a good and anatomically informative fossil record, and a relatively slow ontogenetic development. They are thus a favourite taxon for illustrating evolution as a historical process, although the stem of the vertebrate tree remains poorly documented by fossils, except for some Early Cambrian forms. Therefore, the characterization of the vertebrates now rests essentially on a small number of developmental characters, mostly involved in the rise of the skull, and whose precursors may occur in other chordates. The tree of the crown-group vertebrates also shows some major morphological gaps due to early extinctions, but a number of Palaeozoic stem gnathostome taxa helps in documenting the agnathan-gnathostome evolutionary transition. However, stem cyclostomes remain elusive. © 2008 Académie des sciences.
CITATION STYLE
Janvier, P. (2009). Les premiers vertébrés et les premières étapes de l’évolution du crâne. Comptes Rendus - Palevol, 8(2–3), 209–219. https://doi.org/10.1016/j.crpv.2008.09.003
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