''Tokummia katalepsis'' is a fossil hymenocarine

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

from the

Burgess Shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fo ...

as found in a quarry in

Marble Canyon Marble Canyon is the section of the Colorado River canyon in northern Arizona from Lee's Ferry to the confluence with the Little Colorado River, which marks the beginning of the Grand Canyon. Lee's Ferry is a common launching point for rive ...

in Canada, lived during

middle Cambrian Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ...

(508 million years old). The animal has

maxilliped An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...

mandibles In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

, ring-shaped around 50 body segments, and subdivided basipods. At the front of the animal, there are a pair of antennae, possible eyes and mandibles with pincers. ''Tokummia'' shows the oldest record of arthropod pincers. Carapaces had length up to long. Its biramous legs had endites (small spikes). It is suggested to be a bottom feeder, being able to walk on the sea floor, and to occasionally swim, and used its pincers to catch prey. The genus name ''Tokummia'' named after Tokumm Creek which runs through the Marble Canyon where it was found. The species name ''katalepsis'' means Greek word for "seizing", "gasping" or "holding". According to research of ''Tokummia'', Hymenocarines like ''Tokummia'', ''

Branchiocaris ''Branchiocaris'' is an extinct genus of Cambrian bivalved arthropod. The type and best known species, ''Branchiocaris pretiosa,'' was described from the Burgess Shale of British Columbia, Canada, in 1929, originally placed in '' Protocaris'', a ...

'', ''

Canadaspis ''Canadaspis'' ("Shield of Canada") is an extinct genus of bivalved Cambrian arthropod, known from North America and China. They are thought to have been benthic feeders that moved mainly by walking and possibly used its biramous appendages to ...

'' and '' Odaraia'' are

stem group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

Mandibulata Mandibulata, termed "mandibulates", is a clade of arthropods that comprises the extant subphyla Myriapoda (millipedes and others), Crustacea and Hexapoda (insects and others). Mandibulata is currently believed to be the sister group of the clade ...

, the group includes millipedes, insects and crustaceans, and this theory is supported in multiple subsequent studies.

References

External links

* * {{Taxonbar, from=Q29585082 Burgess Shale fossils Fossil taxa described in 2017 Hymenocarina Cambrian genus extinctions