''Mobulavermis'' () (meaning "Mobula worm") is an extinct genus of

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

lobopodian The lobopodians, members of the informal group Lobopodia (from the Greek language, Greek, meaning "blunt feet"), or the formally erected phylum Lobopoda Cavalier-Smith (1998), are panarthropods with stubby legs called lobopods, a term which may ...

from the

Pioche Shale The Pioche Shale is an Early to Middle Cambrian Burgess shale-type Lagerstätte in Nevada. It spans the Early–Middle Cambrian boundary; fossils from the Early Cambrian are preserved in botryoidal hematite, whereas those from the Middle Cambria ...

, the Combined Metals Member of the

Pioche Formation The Pioche Formation is a geologic formation in Utah and Nevada. It preserves fossils dating back to the Cambrian period. See also * List of fossiliferous stratigraphic units in Utah * Paleontology in Utah * Pioche, Nevada Pioche is an uni ...

in Nevada;

USA The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

. The type species is ''M. adustus'', known from the holotype and paratype.

Etymology

The generic name, ''Mobulavermis'' () comes from ' ''Mobula''', the genus name of extant manta rays and devil rays. This draws comparison to the elongate flexible caudal spines and broad swimming flaps of ''Mobula'' rays, which resemble the outline of the new taxon. This is combined with the Latin 'vermis', which translates to "worm". The specific name, ''adustus'' () is a Latin word which can mean "burnt", "singed", or "sun-burnt". This is in reference to the dramatic yellow, red, and black coloration of the two known specimens, and to the arid conditions of the type locality.

Description

''Mobulavermis'' is known from two specimens which were described by McCall, (2023). The intact posterior region of the holotype, KUMIP 298510, measures around down the curve of the body. The paratype, KUMIP 298511, measures roughly ~ along the sagittal curve of the trunk, and is also an incomplete individual which preserves the posterior portion of the body, although traces of the trunk and flaps continue towards the anterior. The trunk is unsclerotized, and lined with fine transverse annulations. A circular structure occurs beside the gut in the holotype - this may represent a digestive gland. It is described as having more lateral flaps than any other known lobopodian or radiodont; at least 18 down the length of the trunk, becoming smaller towards the caudal spine in an acuminate distribution. The posterior margins of the flaps are smooth and round, while the anterior margins appear flatter. The flaps were perhaps only weakly textured, in comparison to the wrinkled flaps of '' Kerygmachela''. The caudal spine transitions smoothly from the trunk portion, apparently shorter and flexible than those of ''Kerygmachela''. Adult individuals may have reached between ~ and ~, based on complete specimens of ''Kerygmachela'', making it large among Cambrian animals. It is thought to have been pelagic, feeding on small prey in the water column, with elongate compound eyes on the underside of the head, also inferred from ''Kerygmachela''.

Classification

20191022 Kerygmachela kierkegaardi without lobopods

In his phylogenetic analysis, McCall, (2023) recovered ''Mobulavermis'' amongst the "gilled lobopodians" (''

Utahnax ''Utahnax vannieri'' is a genus of kerygmachelid lobopodian from the Drumian of Utah, either from the Marjum or Wheeler formation. Description ''Utahnaxs preserved section is roughly long, with at least eight pairs of ventral flaps simila ...

'', and '' Kerygmachela''). The paper also finds that "gilled lobopodians" form a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

clade,

Kerygmachelidae Kerygmachelidae is a family of gilled lobopodians (stem-arthropods with flapping trunk appendages and radial mouths) from the Cambrian period. Currently three genera are included in the family: '' Kerygmachela'' from the lower Cambrian of Green ...

, which is also erected in the same paper, although had been used informally to refer to the group in lieu of an established clade name. Previously, it had been suggested that ''Kerygmachela'' and ''Utahnax'' may have evolved their lateral flaps independently from radiodonts, opabiniids, and '' Pambdelurion'' through a flattening of the walking lobopods of its ancestors, and that the lobopod limbs of ''Kerygmachela'' had been insufficiently demonstrated. The description of a new kerygmachelid that clearly lacked lobopodous legs appears to have confirmed this hypothesis. The following cladogram represents the phylogenetic results of a 50% majority rule consensus tree.

References

{{Taxonbar, from=Q121769013 Lobopodia Taxa described in 2023 Fossil taxa described in 2023 Cambrian Nevada