''Carbotubulus'' is a genus of extinct worm belonging to the group

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

and known from the Carboniferous Carbondale Formation of the

Mazon Creek The Mazon Creek fossil beds are a conservation ' found near Morris, in Grundy County, Illinois. The fossils are preserved in ironstone concretions, formed approximately in the mid-Pennsylvanian epoch of the Carboniferous period. These concre ...

area in Illinois, US. A

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus, it contains one species ''Carbotubulus waloszeki''. It was discovered and described by Joachim T. Haug, Georg Mayer, Carolin Haug, and Derek E.G. Briggs in 2012. With an age of about 300 million years, it is the first long-legged lobopodian discovered after the period of Cambrian explosion.

Discovery and naming

''Carbotubulus'', represented by a single fossil, was discovered by Joachim T. Haug (

University of Greifswald The University of Greifswald (; german: Universität Greifswald), formerly also known as “Ernst-Moritz-Arndt University of Greifswald“, is a public research university located in Greifswald, Germany, in the state of Mecklenburg-Western ...

, Germany), Georg Mayer (

Leipzig University Leipzig University (german: Universität Leipzig), in Leipzig in Saxony, Germany, is one of the world's oldest universities and the second-oldest university (by consecutive years of existence) in Germany. The university was founded on 2 Decemb ...

), Carolin Haug (

Yale University Yale University is a Private university, private research university in New Haven, Connecticut. Established in 1701 as the Collegiate School, it is the List of Colonial Colleges, third-oldest institution of higher education in the United Sta ...

, US), and Derek E.G. Briggs (Yale University) from the Carbondale Formation ( Francis Creek Shale Member) of the Mazon Creek area in Illinois, US. It was recovered from the location named Pit 11 along with a fossil of an extinct

velvet worm Onychophora (from grc, ονυχής, , "claws"; and , , "to carry"), commonly known as velvet worms (due to their velvety texture and somewhat wormlike appearance) or more ambiguously as peripatus (after the first described genus, ''Peripatus' ...

'' Helenodora inopinata'' (also mentioned as ''Ilyodes inopinata'')''.'' The original fossil is kept at the Royal Ontario Museum in Toronto. The name is derived from Latin words, ''carbo'', referring to the geological age Carboniferous; and ''tubulus'', meaning "small pipe", a description for the pipe-like legs. The specific name is after the German zoologist Dieter Waloszek, one of the leaders in the study of

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

evolution.

Description

''Carbotubulus'' is a soft-bodied worm with stumpy legs called

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

. It has nine pairs of lobopods that are tube-like and elongated. Unlike other lobopodians, its head is relatively large and cylindrical in shape, occupying about one-third of the body length. In other related hallucigeniid worms, the head is usually rounded and tiny such that it is often difficult to describe. Living around 300 million years ago, it supports the fact that Cambrian-type worms survived for over 200 million years after extinction events during the Middle

Cambrian The Cambrian Period ( ; sometimes symbolized 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 years ag ...

(between 510 and 502 million years ago) by which most Cambrian animals disappeared. Majority of the long-legged lobopodians such as ''

Hallucigenia ''Hallucigenia'' is a genus of Cambrian animal resembling worms, known from articulated fossils in Burgess Shale-type deposits in Canada and China, and from isolated spines around the world. The generic name reflects the type species' unusual ...

'', ''

Paucipodia ''Paucipodia inermis'' is a lobopod The lobopodians, members of the informal group Lobopodia (from the Greek, meaning "blunt feet"), or the formally erected phylum Lobopoda Cavalier-Smith (1998), are panarthropods with stubby legs called lobo ...

'' and ''

Orstenotubulus ''Orstenotubulus'' is a genus of lobopodian known from Orsten The Orsten fauna are fossilized organisms preserved in the Orsten lagerstätten of Cambrian (Late Miaolingian to Furongian) rocks, notably at Kinnekulle and on the island of Öland, ...

'' are known only during the Cambrian explosion. When ''Carbotubulus'' was first described, its systematic position was not clear and was loosely assigned to the phylum Arthropoda. Discovery of Cambrian lobopod '' Ovatiovermis cribratus'' 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 fos ...

in 2017 led to a reanalysis of lobopodian classification, and ''Carbotubulus'' was assigned to a group

Panarthropoda 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 paraphyletic ...

, specifically belonging to the family Hallucigeniidae along with the various species of ''Hallucigenia'' and ''

Cardiodictyon catenulum ''Cardiodictyon'' is a genus of lobopodian known from 518 millions years old Chengjiang Lagerstätte. 525 millions years old partial fossil is also reported. It has ~25 pairs of legs, each associated with a pair of dorsal plates. Each leg term ...

.'' This classification is still controversial, especially after the discovery of the second post-Cambrian (

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago (Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozoi ...

) long-legged lobopodian, ''

Thanahita distos ''Thanahita'' is a genus of extinct lobopodian and known from the middle Silurian Herefordshire Lagerstätte at the England–Wales border in UK. It is monotypic and contains one species, ''Thanahita distos.'' Discovered in 2018, it is estimated ...

'', from the

Herefordshire Lagerstätte Coalbrookdale Formation, earlier known as Wenlock Shale or Wenlock Shale Formation and also referred to as Herefordshire Lagerstätte in palaeontology, is a fossil-rich deposit ('' Konservat-Lagerstätte'') in Powys and Herefordshire at the Engla ...

at the

England–Wales border The England–Wales border ( cy, Y ffin rhwng Cymru a Lloegr; shortened: Ffin Cymru a Lloegr), sometimes referred to as the Wales–England border or the Anglo-Welsh border, runs for from the Dee estuary, in the north, to the Severn estuary ...

in UK in 2018. The new interpretation suggest that ''Carbotubulus'' and ''Cardiodictyon'' may lie outside the hallucigeniid family.

References

{{taxonbar, from = Q110588663 Fossil taxa described in 2012 Carboniferous Illinois Lobopodia Carboniferous genus extinctions