Editing Craniate (section)

==Validity==
The validity of the taxon "Craniata" was recently examined by Delarbre et al. (2002) using [[mtDNA]] [[DNA sequence|sequence]] data, concluding that Myxini is more closely related to [[Hyperoartia]] than to Gnathostomata - i.e., that modern jawless fishes form a clade called [[Cyclostomata]]. The argument is that, if Cyclostomata is indeed monophyletic, Vertebrata would return to its old content ([[Gnathostomata]] + [[Cyclostomata]]) and the name Craniata, being superfluous, would become a junior synonym.

The new evidence removes support for the hypothesis for the evolutionary sequence by which (from among [[tunicate]]-like chordates) first the hard cranium arose as it is exhibited by the hagfishes, then the backbone as exhibited by the lampreys, and then finally the hinged jaw that is now ubiquitous. In 2010, [[Philippe Janvier]] stated:
{{quote|Although I was among the early supporters of vertebrate paraphyly, I am impressed by the evidence provided by Heimberg et al. and prepared to admit that cyclostomes are, in fact, monophyletic. The consequence is that they may tell us little, if anything, about the dawn of vertebrate evolution, except that the intuitions of 19th century zoologists were correct in assuming that these odd vertebrates (notably, hagfishes) are strongly degenerate and have lost many characters over time.<ref>"MicroRNAs revive old views about jawless vertebrate divergence and evolution." Proceedings of the National Academy of Sciences (USA) 107:19137-19138. [http://www.pnas.org/content/107/45/19137.full.pdf+html]</ref>}}