''Rhyniognatha'' is an extinct

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 ...

of arthropod of disputed placement. It has been considered in some analyses as the oldest

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, ...

known, as well as possibly being a flying insect. ''Rhyniognatha'' is known from a partial head with preserved mouthparts from the

Early Devonian The Early Devonian is the first of three Epoch (geology), epochs comprising the Devonian period, corresponding to the Lower Devonian Series (stratigraphy), series. It lasted from and began with the Lochkovian Stage , which was followed by the Pr ...

aged

Rhynie chert The Rhynie chert is a Lower Devonian Sedimentary rock, sedimentary deposit exhibiting extraordinary fossil detail or completeness (a Lagerstätte). It is exposed near the village of Rhynie, Aberdeenshire, Scotland; a second unit, the Windyfield ...

around 400 million years ago, when Earth’s first terrestrial

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

s were being formed. The type, and only species is ''R. hirsti'', which was named and described in 1928.R. J. Tillyard. 1928. Some remarks on the Devonian fossil insects from the Rhynie chert beds, Old Red Sandstone. ''Transactions of the Entomological Society of London'' 76:65-71 Other analyses have interpreted the specimen as a

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 ...

Evidence

Partial restorations of Rhyniognatha as myriapod

The head part of a specimen, preserved in a fragment of

Rhynie Chert The Rhynie chert is a Lower Devonian Sedimentary rock, sedimentary deposit exhibiting extraordinary fossil detail or completeness (a Lagerstätte). It is exposed near the village of Rhynie, Aberdeenshire, Scotland; a second unit, the Windyfield ...

, was collected in 1919 by the Reverend W. Cran, who provided it to S. Hirst, Samarendra Maulik and D.J. Scourfield. Hirst and Maulik published a report in 1926; in it they described ''

Rhyniella praecursor ''Rhyniella'' is a genus of fossil springtails (Collembola) from the Rhynie chert, which formed during the Pragian, Pragian stage of the Early Devonian. One species has been described, ''Rhyniella praecursor''. For some time it was believed to be ...

'', which is now known to be a

springtail Springtails (class Collembola) form the largest of the three lineages of modern Hexapoda, hexapods that are no longer considered insects. Although the three lineages are sometimes grouped together in a class called Entognatha because they have in ...

. Several other pieces, including the ''Rhyniognatha'' head, were also described as "supposed

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

l insect" though yet unnamed. The specimen was named as ''Rhyniognatha hirsti'' in 1928 by entomologist Robin J. Tillyard. It was later donated by D.J. Scourfield to the

Natural History Museum A natural history museum or museum of natural history is a scientific institution with natural history scientific collection, collections that include current and historical records of animals, plants, Fungus, fungi, ecosystems, geology, paleo ...

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

where it is currently displayed on a microscope slide. In 2004 Michael S. Engel and David A. Grimaldi (2004) analyzed ''Rhyniognatha hirsti's'' mouthparts, and came to the conclusion that ''Rhyniognatha'' likely had wings, as they determined the mouthparts resembled those of a

mayfly Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the orde ...

, a flying insect. Nevertheless, a detailed reanalysis by Carolin Haug & Joachim T. Haug in 2017 came to a different interpretation, concluding that the identity of ''Rhyniognatha hirsti'' as a

, specifically a scutigeromorph

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

, was better supported by the available evidence, without being able to exclude an insect identity completely.

References

{{Taxonbar, from1=Q1946495, from2=Q20672205 Paleozoic insects of Europe Enigmatic arthropod taxa Fossil taxa described in 1928 Fossils of Great Britain Transitional fossils Monotypic prehistoric insect genera Taxa named by Robert John Tillyard Controversial taxa