A possible Cambrian stem-group gnathiferan-chaetognath from the Weeks Formation (Miaolingian) of Utah

In recent years the plethora of “weird wonders”, the vernacular for the apparently extinct major bodyplans documented in many of the Cambrian Lagerstätten, has been dramatically trimmed. This is because various taxa have either been assigned to known phyla or at least accommodated in larger monophyletic assemblages. Nevertheless, a number of Cambrian taxa retain their enigmatic status. To this intriguing roster we add Dakorhachis thambus n. gen. n. sp., from the Miaolingian (Guzhangian) Weeks Formation Konservat-Lagerstätte of Utah. Specimens consist of an elongate body lacking appendages, but which is apparently segmented. A prominent feeding apparatus consists of a circlet of triangular teeth, while posteriorly there are three distinct skeletal components. D. thambus n. sp. is interpreted as an ambush predator and may have been partially infaunal. The wider affinities of this new taxon remain conjectural but it is suggested that it may represent a stem-group member of the Gnathifera, today represented by the gnathostomulids, micrognathozoans, rotifers, and possibly with links also to the chaetognaths.