''Thanahita'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of extinct

lobopodian 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 middle

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 ...

Herefordshire Lagerstätte 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. It is

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 ...

and contains one species, ''Thanahita distos.'' Discovered in 2018, it is estimated to have lived around 430 million years ago and is the only known extinct lobopodian in Europe, and the first Silurian lobopodian known worldwide.

Discovery

''Thanahita'' was discovered in 2018 during a palaeontological expedition funded by the

Natural Environment Research Council The Natural Environment Research Council (NERC) is a British research council that supports research, training and knowledge transfer activities in the environmental sciences. History NERC began in 1965 when several environmental (mainly geog ...

(NERC) and the

Leverhulme Trust The Leverhulme Trust () is a large national grant-making organisation in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the n ...

. The team of researchers comprised Derek J. Siveter (

University of Oxford The University of Oxford is a collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the world's second-oldest university in contin ...

), Derek E. G. Briggs (

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 ...

), David J. Siveter (

University of Leicester , mottoeng = So that they may have life , established = , type = public research university , endowment = £20.0 million , budget = £326 million , chancellor = David Willetts , vice_chancellor = Nishan Canagarajah , head_la ...

), Mark D. Sutton (

Imperial College London Imperial College London (legally Imperial College of Science, Technology and Medicine) is a public research university in London, United Kingdom. Its history began with Prince Albert, consort of Queen Victoria, who developed his vision for a ...

) and David Legg (

University of Manchester The University of Manchester is a public university, public research university in Manchester, England. The main campus is south of Manchester city centre, Manchester City Centre on Wilmslow Road, Oxford Road. The university owns and operates majo ...

). The

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

was discovered from the Herefordshire Lagerstätte, which has been known to be a rich source of fossils of diverse animals. The only fossil of ''Thanahita'' (designated OUMNH C.29699) was collected from the upper part of Wenlock Series of the Lagerstätte. The scientific genus name is derived from the Greek word, ''

Theia In Greek mythology, Theia (; grc, Θεία, Theía, divine, also rendered Thea or Thia), also called Euryphaessa ( grc, Εὐρυφάεσσα) "wide-shining", is one of the twelve Titans, the children of the earth goddess Gaia and the sky god ...

'', meaning goddess, and

Anahita Anahita is the Old Persian form of the name of an Iranian goddess and appears in complete and earlier form as ('), the Avestan name of an Indo-Iranian cosmological figure venerated as the divinity of "the Waters" ( Aban) and hence associ ...

, an ancient Indo-Iranian deity of ‘the Waters’ (in Persian); while the specific name comes from the Greek ''distolos'', meaning in pairs, plus ''acherdos'', meaning a hedge shrub, alluding to the bilateral tufted papillae on the trunk.

Morphology

''Thanahita'' is an animal with elongated worm-like body and at least 9 pairs of stumpy legs called lobopods. The only available fossil is not complete and the entire structure is not known. However, it is preserved in a three-dimenstional structure from which the remaining body parts could be nicely examined. The body has three main parts: the head, neck and trunk. The head appears to be oval shaped, but much of it is missing. With the missing head part, the entire body length is 3 cm and about 2 mm wide. The neck has at least 2 pairs of

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

-like legs that are smaller than the legs at the trunk. There are 7 pairs of legs on the trunk. Each leg bears one or two claws; leg number 4 and 5 having two claws, while leg 6 to 9 have one claw each. All the legs are arranged with a space of about 0.8 mm in between. Semicircular papillae or

sclerites A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...

are present on is back throughout most of its body length. These papillae are not uniformly present in each transverse line of the body, and are in pairs in some part but singly in the posterior region. The papillae bear tufts on their surfaces. The tufts are arranged in a grid, four columns wide, with about four rows of tufts per leg segment from the neck to the posterior end.

Taxonomy

''Thanahita'' possess some shared features (e.g. anterior pairs of slender legs; reduced tail) with ''

Cardiodictyon ''Cardiodictyon'' is a genus of 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 ...

'', '' Carbotubulus,'' and ''

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 ...

,'' which have been classified within a single

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Hallucigeniidae. Thus, ''Thanahita'' also belongs to the same family, with ''Thanahita'' being a basal member or ''Hallucigenia'' as its closest relative. Since it is younger than other hallucigeniids, it is likely one of the last member of the family before the evolution of velvet worms ( onychophorans), an extant panarthropod phylum which may or may not closely related to hallucigeniids.

References

{{Lobopodia Fossil taxa described in 2018 Lobopodia Silurian United Kingdom Paleontology in the United Kingdom Silurian genus extinctions