Careful amendment of morphological data sets improves phylogenetic frameworks: re-evaluating placement of the fossil <i>Amiskwia sagittiformis</i>

The Cambrian fossil Amiskwia sagittiformis has puzzled palaeontologists for more than a century, but recent re-investigation of its morphology suggested close relationship with the bilaterian clade Gnathifera, comprising Rotifera, Gnathostomulida and Micrognathozoa. Since already been considered closely related to Chaetognatha, this new interpretation supports molecular developmental studies finding phylogenetic between Chaetognatha Gnathifera. re-description jaw apparatus first analysis by Vinther & Parry (2019 Vinther, J. Parry, L. A. 2019. Bilateral elements in bridge morphological gap gnathiferans chaetognaths. Current Biology, 29(5), 881–888.[Crossref], [PubMed], [Web Science ®] , [Google Scholar]) found rather surprising topology being sister groups nested inside Furthermore, subsequent paper from Caron Cheung Caron, J.-B. Cheung, B. is large gnathiferan complex gnathostomulid-like jaws. Communications 2, 164. doi:10.1038/s42003-019-0388-4[Crossref], re-described jaws as very similar configuration Gnathostomulida, did not include any analysis. Here we test various parsimony Bayesian analyses, taking into account description careful re-amendment matrix Parry. According our results findings on phylogeny their extant members, suggest systematization these taxa. We recovered stem-group chaetognath within Cucullophora nov., rejecting hypothesis affinity consensual monophyletic Gnathifera group Cucullophora, all together forming Chaetognathifera. Rotifera + Micrognathozoa form named Gynognathifera nov. discuss characters supporting each reasons that Finally, hope carefully amended focused formal classification robust phylogeny, will be use future palaeontology clades.