''Utahnax vannieri'' is a genus of kerygmachelid lobopodian from the

Drumian The Drumian is a stage of the Miaolingian Series of the Cambrian. It succeeds the Wuliuan and precedes the Guzhangian. The base is defined as the first appearance of the trilobite ''Ptychagnostus atavus'' around million years ago. The top is def ...

of Utah, either from the Marjum or

Wheeler Wheeler may refer to: Places United States * Wheeler, Alabama, an unincorporated community * Wheeler, Arkansas, an unincorporated community * Wheeler, California, an unincorporated community * Wheeler, Illinois, a village * Wheeler, Indiana, a ...

formation.

Description

''Utahnaxs preserved section is roughly long, with at least eight pairs of ventral flaps similar to those found on '' Kerygmachela''. Unusually, it does not appear to have had legs, suggesting the ventral flaps are broadened lobopods similar to the ventral flaps on radiodonts, and casting doubt on whether ''Kerygmachela'' had legs or whether reported “lobopods” are actually muscles of the flaps. In addition, it may have borne complex digestive glands similar to those of

radiodonts Radiodonta is an extinct order of stem-group arthropods that was successful worldwide during the Cambrian period. They may be referred to as radiodonts, radiodontans, radiodontids, anomalocarids, or anomalocaridids, although the last two origi ...

Ecology

As ''Utahnax'' nests firmly within the predatory clade of “gilled lobopodians”, it can be assumed that it was also predatory. Its lack of lobopods also suggests it was primarily if not wholly pelagic, occupying a similar niche to radiodonts. This may explain the paucity of gilled lobopodians in the fossil record, as they may have competed with radiodonts in the pelagic predatory niches.

Etymology

The genus name ''Utahnax'' is derived from Utah, where it was found, and the Greek word ''anax'', meaning “king” or “ruler”. The species name ''vannieri'' honours Jean Vannier for their extensive work on fossil ecdysozoans.

Distribution

''Utahnax'' is known from only a singular part and counterpart. As the fossil was not precisely labelled, it is unknown where exactly it was found in Utah, although an origin in the

Weeks Formation The Weeks Formation is a geologic formation in Utah. It preserves fossils dating back to the Cambrian period and more specifically the Guzhangian stage. Its upper part has yielded a diverse fauna dominated by trilobites and brachiopods, but als ...

or most of the Wheeler Shale can be ruled out due to differing fossil preservation methods.

References

{{taxonbar, from1=Q125019781 Cambrian life Dinocaridida Prehistoric arthropods Fossils of the United States Paleontology in Utah Prehistoric animals of North America Cambrian arthropods of North America Paleozoic life of North America Paleozoic United States Cambrian United States Paleozoic animals Prehistoric animal genera Prehistoric animals Prehistoric animal families