''Facivermis'' (meaning "torch worm"
) is a genus of sessile
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 Lower
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 ...
Maotianshan shales
The Maotianshan Shales are a series of Cambrian, Early Cambrian deposits in the Chiungchussu Formation, famous for their ''Lagerstätte, Konservat Lagerstätten'', deposits known for the exceptional preservation of fossilized organisms or traces. ...
of
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
[
]
Anatomy
''Facivermis'' was a worm
Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always).
Worms vary in size from microscopic to over in length for marine polychaete wor ...
-like creature up to 90 mm long. Its body was divided into three sections. The anterior section had five equally sized pairs of appendages with two setal rows along the margins. The middle section was elongate and five times longer than the anterior or posterior. The posterior section was pear-shaped and had three rows of hooks surrounding the anus.
Classification
''Facivermis'' was considered by its describers to be a polychaete
Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that ...
worm
Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always).
Worms vary in size from microscopic to over in length for marine polychaete wor ...
.[ An affinity to the unusual ]crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
lineage Pentastomida
The Pentastomida are an enigmatic group of parasitic arthropods commonly known as tongue worms due to the resemblance of the species of the genus ''Linguatula'' to a vertebrate tongue; molecular studies point to them being degenerate crustaceans. ...
has also been proposed, but is seen as unlikely.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 ...
.[ Liu ''et al.'' draw a comparison to the known ]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 ...
'' Miraluolishania''. Liu ''et al.'' also note that the pear-shaped end bears a close resemblance to the proboscis of priapulid
Priapulida (priapulid worms, from Gr. πριάπος, ''priāpos'' 'Priapus' + Lat. ''-ul-'', diminutive), sometimes referred to as penis worms, is a phylum of unsegmented marine worms. The name of the phylum relates to the Greek god of fertility ...
worms if it is interpreted as being the anterior end.[ The possible ]priapulid
Priapulida (priapulid worms, from Gr. πριάπος, ''priāpos'' 'Priapus' + Lat. ''-ul-'', diminutive), sometimes referred to as penis worms, is a phylum of unsegmented marine worms. The name of the phylum relates to the Greek god of fertility ...
"Xishania" ''longiusulas fragmentary remains closely resembles the pear-shaped end of ''Facivermis'', so Huang ''et al.'' assigned "X". ''longiusula'' to ''Facivermis'' as a second species.tube worm
A tubeworm is any worm-like sessile invertebrate that anchors its tail to an underwater surface and secretes around its body a mineral tube, into which it can withdraw its entire body.
Tubeworms are found among the following taxa:
* Annelida, the ...
-like 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 ...
belonging to Luolishaniidae
The Luolishaniidae or Luolishaniida are a group of Cambrian and Ordovician lobopodians with anterior 5 or 6 pairs of setiferous lobopods. Most luolishaniids also have posterior lobopods each with a hooked claws, and thorn-shaped sclerites arran ...
, with a bulbous posterior.
Ecology
''Facivermis'' was previously interpreted as a predator that anchored itself into sediment with its hooked posterior end and used its anterior appendages to catch prey.[ One fossil has a possible ]bradoriid
Bradoriids are an extinct order of small marine arthropods with a bivalved carapace, and were globally distributed, forming a significant portion of the Cambrian and Early Ordovician soft-bodied communities.
Affinity
Whilst the Bradoriida ...
preserved in its gut.[ The new specimens suggest a lifestyle similar to feather duster worms, with the anterior hooks used to anchor itself into sediment.]
References
{{Taxonbar, from=Q5428654
Cambrian animals
Lobopodia
Cambrian genus extinctions