Browse/search for people

Publication - Dr Jakob Vinther

    Bilateral Jaw Elements in Amiskwia sagittiformis Bridge the Morphological Gap between Gnathiferans and Chaetognaths

    Citation

    Vinther, J & Parry, L, 2019, ‘Bilateral Jaw Elements in Amiskwia sagittiformis Bridge the Morphological Gap between Gnathiferans and Chaetognaths’. Current Biology, vol 29., pp. 881-888.e1

    Abstract

    Amiskwia sagittiformis Walcott 1911 is an iconic soft bodied taxon from the Burgess Shale [1-3]. Originally interpreted as a chaetognath [1], but later interpreted as a pelagic nemertean [2], or considered of uncertain affinity [3]. Part of this ambiguity is due to direct comparisons with members of the crown groups of extant phyla [4] and a lack of clarity regarding the systematic position of chaetognaths, which would allow for assessing character polarity in the phylum with respect to outgroups. Here we show that Amiskwia preserves a bilaterally arranged set of head structures visible in relief and high reflectivity. These structures are best interpreted as jaws situated within an expanded pharyngeal complex. Morphological studies have highlighted likely homology between bilateral and chitinous jaw elements in gnathiferans and chaetognaths [5], which is congruent with a shared unique HOX gene that suggest a close relationship between Gnathifera and Chaetognatha [6]. Molecular phylogenetic studies have recently found gnathiferans to be a deep branch of Spiralia and Chaetognaths either a sister group to Spiralia [7] or forming a clade with gnathiferans [6, 8]. Our phylogenetic analyses renders Gnathifera paraphyletic with respect to Chaetognatha and we therefore suggest that Amiskwia is best interpreted as a stem chaetognath, but crown gnathiferan.

    Full details in the University publications repository