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

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

lobopodian Lobopodians are members of the informal group Lobopodia (), or the formally erected phylum Lobopoda Cavalier-Smith (1998). They are panarthropods with stubby legs called lobopods, a term which may also be used as a common name of this group as w ...

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 Cambrian ...

, the Combined Metals Member of the Pioche Formation in

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

;

USA The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguous ...

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

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

and

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype (biology), isotype ...

Etymology

The generic name, ''Mobulavermis'', comes from ''

Mobula ''Mobula'' is a genus of Batoidea, rays in the family Mobulidae that is found worldwide in tropical and warm, temperate seas. Some authorities consider this to be a subfamily of the Myliobatidae (eagle rays). Their appearance is similar to that o ...

'', the genus name of extant

manta rays Manta rays are large Batoidea, rays belonging to the genus ''Mobula'' (formerly its own genus ''Manta''). The larger species, ''Giant oceanic manta ray, M. birostris'', reaches in width, while the smaller, ''Reef manta ray, M. alfredi'', reac ...

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 Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

'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 The sagittal plane (; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections. It is perpendicular to the transverse plane, transverse and coronal plane, coronal planes. The plane may be in ...

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 Radiodonta is an extinct order of stem-group arthropods that was successful worldwide during the Cambrian period. Radiodonts are distinguished by their distinctive frontal appendages, which are morphologically diverse and were used for a variety ...

; 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 ''Kerygmachela kierkegaardi'' is a Kerygmachelidae, kerygmachelid Lobopodia#Gilled lobopodians, gilled lobopodian from the Cambrian Stage 3 aged Sirius Passet Lagerstätte in northern Greenland. Its anatomy strongly suggests that it, along with i ...

''. 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 The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

, feeding on small prey in the water column, with elongate

compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...

on the underside of the head, also inferred from ''Kerygmachela''.

Classification

20191022 Kerygmachela kierkegaardi without lobopods

In his

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis, McCall, (2023) recovered ''Mobulavermis'' amongst the "gilled lobopodians" ('' Utahnax'', and ''

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

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

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 Greenla ...

, 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 ''Pambdelurion'' is an extinct genus of Panarthropoda, panarthropod from the Cambrian aged Sirius Passet site in northern Greenland. Like the morphologically similar ''Kerygmachela'' from the same locality, ''Pambdelurion'' is thought to be closel ...

'' 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 A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

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