''Wingertshellicus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

that has been found in

Hunsrück Slate The Hunsrück () is a long, triangular, pronounced upland in Rhineland-Palatinate, Germany. It is bounded by the valleys of the Moselle-Saar (north-to-west), the Nahe (south), and the Rhine (east). It is continued by the Taunus mountains, past ...

, that is located in the

Rhenish Massif The Rhenish Massif, Rhine Massif or Rhenish Uplands (, : 'Rhenish Slate Uplands') is a geologic massif in western Germany, eastern Belgium, Luxembourg and northeastern France. It is drained centrally, south to north by the river Rhine and a few ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

, and lived about 405 million years ago, during the Lower

Emsian The Emsian is one of three faunal stages in the Early Devonian Epoch. It lasted from 410.62 ±1.95 million years ago to 393.47 ±0.99 million years ago. It was preceded by the Pragian Stage and followed by the Eifelian Stage. It is named after ...

(part of the Lower

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

Etymology

''Wingertshellicus'' has been named after the Wingertshell Member, part of the

near the German town of Bundenbach, in which it was found.

Morphology

''Wingertshellicus'' measured about long. The body of consists of just two main parts ( tagmata): a short head and an elongated trunk. The head possess a pair of large stalked

compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...

and 7 pairs of appendages. The first appendages are long, annulated antennae. Within the remaining 6 pairs of leg-like appendages, the anterior 2 pairs are short and stout while the posterior 3 pairs were significantly elongated. The segmentation of the post-antennular appendages obscured by their limited preservation. A ventral triangular projection with terminal

mouth A mouth also referred to as the oral is the body orifice through which many animals ingest food and animal communication#Auditory, vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also t ...

opening located between the posteroir appendages. There is no complex mouthparts (e.g.

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

; labium) nor subdivision of a thorax for the 6 elongated appendages like those of an

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

. The trunk comprises about 40 similar segments (

somites The somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryonic stage of somitogenesis, along the head-to-tail axis in segmented animals. In vertebrates, somites subdivide in ...

), each carried a pair of biramous appendages with enlarged basipod (basal segment), flap-like exopods (outer branch) and slender endopods (inner branch). The appendages were subequal, lacking any evidence of specializations. the trunk terminated by a pair of fluke-like appendages with flagellate structures.

Taxonomy

''Wingertshellicus backesi'' was originally described in 2001 from specimens that were exposed on their belly (or

ventrally Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

), and was tentatively identified as a crustaceanomorph at that time. Two years later, ''Devonohexapodus bocksbergensis'' was erected based on a specimen on its side (or laterally) from the same

stratum In geology and related fields, a stratum (: strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ...

. At first sight, it seems that the ventrally exposed specimens only have small and slender appendages, while the laterally exposed has three pairs of long and stout legs, hence the description of the latter as a new species of hexapod (a

subphylum In zoological nomenclature, a subphylum is a taxonomic rank below the rank of phylum. The taxonomic rank of " subdivision" in fungi and plant taxonomy is equivalent to "subphylum" in zoological taxonomy. Some plant taxonomists have also used th ...

of arthropod compose of

insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...

and close-related taxa). The lateral specimen were interpreted as a marine

stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...

-hexapod originated just before the split of

entognatha The Entognatha, from Ancient Greek ἐντός (''entós''), meaning "inside", and γνάθος (''gnáthos''), meaning "jaw", are a class (biology), class of wingless and Ametabolism, ametabolous arthropods, which, together with the insects, ...

n and true insect (Ectognatha) lineages, suggest the origin of the definitive six-legged thorax evolved before the terrestrialization of hexapod ancestors. The initial diagnoses of the lateral specimen, particularly the three pairs of legs, seemed to substantiate tentative finds based on genetic and ontogenetic studies that insects have a different crustacean ancestry than other land arthropods such as

spiders Spiders (order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species di ...

and

centipedes Centipedes (from Neo-Latin , "hundred", and Latin language, Latin , "foot") are predatory arthropods belonging to the class Chilopoda (Ancient Greek , ''kheilos'', "lip", and Neo-Latin suffix , "foot", describing the forcipules) of the subphyl ...

. However, detailed redescription in 2009 showed that the vertrally and laterally exposed specimen share the same

tagmosis In biology, a tagma (Greek: τάγμα, : tagmata – τάγματα - body of soldiers; battalion) is a specialized grouping of multiple segments or metameres into a coherently functional morphological unit. Familiar examples are the head, th ...

(only head and trunk), long and slender antennas, two large eyes on stalks, the same number, make up and attachment of the head appendages, the same number of segments in the abdomen, small abdominal appendages and two tail flukes at the rear. In the

soft parts are preserved in

pyrite The mineral pyrite ( ), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue ...

and may represent the infill of the original

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

. In other species the thickness of the appendages turns out to be highly variable dependent upon the orientation with respect to the bedding plain. So the apparent differences in the thickness of the appendages occurred between the ventral and lateral specimens does not necessarily indicate taxonomic difference. As the result, ''Devonohexapodus'' turns out to be a

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of ''Wingertshellicus'', the validity as an indication for early hexapod evolution by the lateral specimen was eventually flawed, since the 6 legs were revealed to be cephalic instead of thoraxic, and other supposed hexapod like-characters (e.g. posterior

gonopods Gonopods are specialized appendages of various arthropods used in reproduction or egg-laying. In males, they facilitate the transfer of sperm from male to female during mating, and thus are a type of intromittent organ. In crustaceans and millipe ...

, cerci) turns out to be either mis- or overinterpretation as well. Due to the lack of mandibles and other taxonomic definitive characters, ''Wingertshellicus'' is not even assignable to

Mandibulata The clade Mandibulata constitutes one of the major subdivisions of the phylum Arthropoda, alongside Chelicerata. Mandibulates include the crustaceans, myriapods (centipedes and millipedes, among others), and all true insects. The name "Mandibul ...

(a clade composed of

myriapod Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. Although molecular evidence and similar fossils suggests a diversifi ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s and hexapods) nor any known arthropod subgroups.

References

{{Taxonbar, from=Q16993525 Devonian arthropods of Europe Fossils of Germany Fossil taxa described in 2001 Hunsrück Slate fossils Controversial taxa