The Protocoleoptera are a

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

group of extinct

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

s, containing the earliest and most primitive lineages of beetles. They represented the dominant group of beetles during the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

, but were largely replaced by modern beetle groups during the following

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

. Protocoleopterans typically possess prognathous (horizontal) heads, distinctive

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

with regular window punctures, culticles with tubercles or scales, as well as a primitive pattern of ventral

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 commonl ...

, similar to the modern archostematan families

Ommatidae The Ommatidae are a family of beetles in the suborder Archostemata. The Ommatidae are considered the extant beetle family that has most ancestral characteristics. There are only seven extant species, confined to Australia and South America. How ...

and

Cupedidae The Cupedidae are a small family of beetles, notable for the square pattern of "windows" on their elytra (hard forewings), which give the family their common name of reticulated beetles. The family consists of about 30 species in 9 genera, with ...

. They are thought to have been

xylophagous Xylophagy is a term used in ecology to describe the habits of an herbivorous animal whose diet consists primarily (often solely) of wood. The word derives from Greek ''ξυλοφάγος'' (''xulophagos'') "eating wood", from ''ξύλον'' (') ...

and wood boring. Kirejtshuk ''et al.'' (2014) argue that the name "Protocoleoptera" should not be used for the group, as Protocoleoptera was originally proposed for the family Protocoleidae , now considered a member of the extinct order

Protelytroptera Protelytroptera is an extinct order of insects thought to be a stem group from which the modern Dermaptera evolved. These insects, which resemble modern Blattodea, or Cockroaches, are known from the Permian of North America, Europe and Austral ...

(a stem-group of the modern

Dermaptera Earwigs make up the insect order Dermaptera. With about 2,000 species in 12 families, they are one of the smaller insect orders. Earwigs have characteristic cerci, a pair of forcep-like pincers on their abdomen, and membranous wings folded ...

, the earwigs). Because of this, Cai ''et al.'' (2022) proposed a replacement name, Alphacoleoptera . In Kirejtshuk (2020), the extinct beetles included in Protocoleoptera were placed within the suborder Archostemata instead.

Taxonomy

The taxonomic naming scheme of early beetles currently has no consenus, with several separate classification schemes proposed for higher level-clades within the stem-group. It is generally agreed that Tshekardocoleidae is the earliest diverging group among the major families. * Coleoptera ** †'' Coleopsis'' Kirejtshuk et al., 2014 ** † Tshekardocoleidae (Early Permian) ** † Permocupedidae (Early Permian-Middle Triassic) ** † Taldycupedidae (Middle-Late Permian) ** † Ademosynidae ** † Permosynidae ** † Rhombocoleidae ** † Triadocupedidae ** † Asiocoleidae ** † Peltosynidae

References

Insect suborders {{paleo-beetle-stub