title: A complete insect from the Late Devonian period.
abstract: After terrestrialization, the diversification of arthropods and vertebrates is thought to have occurred in two distinct phases, the first between the Silurian and the Frasnian stages (Late Devonian period) (425-385 million years (Myr) ago), and the second characterized by the emergence of numerous new major taxa, during the Late Carboniferous period (after 345 Myr ago). These two diversification periods bracket the depauperate vertebrate Romer's gap (360-345 Myr ago) and arthropod gap (385-325 Myr ago), which could be due to preservational artefact. Although a recent molecular dating has given an age of 390 Myr for the Holometabola, the record of hexapods during the Early-Middle Devonian (411.5-391 Myr ago, Pragian to Givetian stages) is exceptionally sparse and based on fragmentary remains, which hinders the timing of this diversification. Indeed, although Devonian Archaeognatha are problematic, the Pragian of Scotland has given some Collembola and the incomplete insect Rhyniognatha, with its diagnostic dicondylic, metapterygotan mandibles. The oldest, definitively winged insects are from the Serpukhovian stage (latest Early Carboniferous period). Here we report the first complete Late Devonian insect, which was probably a terrestrial species. Its 'orthopteroid' mandibles are of an omnivorous type, clearly not modified for a solely carnivorous diet. This discovery narrows the 45-Myr gap in the fossil record of Hexapoda, and demonstrates further a first Devonian phase of diversification for the Hexapoda, as in vertebrates, and suggests that the Pterygota diversified before and during Romer's gap.
authors.affiliation: UMR CNRS 7205, CP 50, Entomologie, Muséum national d'Histoire naturelle, 45 rue Buffon, F-75005 Paris, France. garroust@mnhn.fr
authors.forename: Romain
authors.initials: R
authors.lastname: Garrouste
authors.forename: Gaël
authors.initials: G
authors.lastname: Clément
authors.forename: Patricia
authors.initials: P
authors.lastname: Nel
authors.forename: Michael S
authors.initials: MS
authors.lastname: Engel
authors.forename: Philippe
authors.initials: P
authors.lastname: Grandcolas
authors.forename: Cyrille
authors.initials: C
authors.lastname: D'Haese
authors.forename: Linda
authors.initials: L
authors.lastname: Lagebro
authors.forename: Julien
authors.initials: J
authors.lastname: Denayer
authors.forename: Pierre
authors.initials: P
authors.lastname: Gueriau
authors.forename: Patrick
authors.initials: P
authors.lastname: Lafaite
authors.forename: Sébastien
authors.initials: S
authors.lastname: Olive
authors.forename: Cyrille
authors.initials: C
authors.lastname: Prestianni
authors.forename: André
authors.initials: A
authors.lastname: Nel
mesh_terms: D000818:Animals; D001530:Belgium; D005075:Biological Evolution; D005580:Fossils; D049690:History, Ancient; D007313:Insecta / Q000033:anatomy & histology* / Q000145:classification; D010802:Phylogeny; D014921:Wings, Animal