Kingdom Animalia Phylum Arthropoda | Subphylum Incertae sedis Rank Genus | |
Species W. backesi Brigs & Bartles, 2001 (type) Similar Mimetaster, Rhyniognatha, Atelocerata, Ectognatha, Entognatha | ||
Wingertshellicus is an extinct genus of arthropod, of average size (approximately 7.5 centimetres or 3.0 inches long), that has been found in Hunsrück Slate, that is located in the Rhenish Massif in Germany, and lived about 405 million years ago, during the Lower Emsian (part of the Lower Devonian). The body consists of just two main parts (or tagmata), a head (or cephalon) and a trunk (or abdomen) that comprises a long row of similar segments (or somites). The relatively small head is dominated by large eyes, and three pairs of long legs (or appendages), making it look like a damselfly nymph, although W. backesi has long antennae, unlike damselflies.
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Etymology
Wingertshellicus has been named after the Wingertshell Member, part of the Hunsrück Slate near the German town of Bundenbach, in which it was found.
Taxonomy
Wingertshellicus backesi was originally described in 2001 from specimens that were exposed on their belly (or ventrally). Two years later, Devonohexapodus bocksbergensis was erected based on a specimen on its side (or laterally). 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 a new species. In the Hunsrück Slate soft parts are preserved in pyrite and may represent the infill of the original cuticle. 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 does not necessarily indicate different species. Detailed comparison showed that the vertrally and laterally exposed specimen share the same tagmosis (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 abdomal appendages and two tail flukes at the rear.
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 and centipedes. Support for several independent evolutionary lines in arthropods resulting in life on land is growing, but Devonohexapodus bocksbergensis has been disproven as missing link.