''Ovatiovermis'' is a genus of filter-feeding lobopodian known 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 ...

. Like many lobopodians, it had nine pairs of lobopods (legs). It was well adapted to filter-feeding and probably did so from the nearest high vantage point.

Morphology

''Ovatiovermis'' had nine pairs of lobopods. The first two pairs were elongate and had approximately 20 pairs of spines on each lobopod, with a bifid claw at each tip. The third to sixth pairs of lobopods were shorter and their paired spines were much smaller. On these four pairs of lobopods the spines were only large near the tip. The last three pairs of lobopods did not have the paired spines, showing that these spines were used for filter-feeding. Instead these lobopods had hooked claws with which it could grip one of the

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...

s or

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throug ...

s found at the time and rear up into the current. At the anterior end of the animal it had an evertible

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elong ...

, with its mouth at the end. This would probably have been used to suck any particles of food which had been caught off the spines, possibly in a similar manner to a sea cucumber. Its head was not well separated from the body. Also on the head ''Ovatiovermis'' had two small (0.1mm diameter) and probably very primitive visual organs. Close examination of the fossils revealed traces of

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

compounds in the claws of the back three legs and around the mouth and proboscis. There were also calcium traces found in the gut, but this may have been fragments of shell attached to its food rather than the animal`s organs.

Etymology

''Ovatiovermis'' comes from the Latin '''ovatio''' 'I clap' and vermis''' 'worm'. This refers to the position it would have adopted when filter-feeding, standing on its rear pairs of lobopods and waving front limbs above its head. ''cribratus'' also comes from Latin, and means 'that which sieves'.

Evolutionary importance

''Ovatiovermis'' was a member of the luolishaniid group of lobopodians. Caron and Aria, in their article on ''Ovatiovermis'', suggest that both luolishaniids and hallucigeniids branched before the last common ancestor of extant

panarthropod Panarthropoda is a proposed animal clade containing the extant phyla Arthropoda, Tardigrada (water bears) and Onychophora (velvet worms). Panarthropods also include extinct marine legged worms known as lobopodians ("Lobopodia"), a paraphylet ...

subphyla (

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 ...

Tardigrada Tardigrades (), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbä ...

and Onchyophora), rather than hallucigeniids and luolishaniids being closely related to onchyophorans. This pushes the date for this splitting well back into the Precambrian. All luolishaniids were filter-feeders, and this is one of the characteristics that they are classified by - the other is the small head and thick neck, unlike in hallucigeniids which had a bulbous head and a thin neck.

References

* * {{Taxonbar, from=Q30692682 Lobopodia Fossil taxa described in 2017