Earliest record of fossil insect oothecae confirms the presence of crown‐dictyopteran taxa in the Late Triassic

Abstract

Although dissimilar in their overall appearance and life habits, the praying mantises (Mantodea) and cockroaches (Blattodea, including their eusocial relatives, the termites [Isoptera]) are grouped within the clade Dictyoptera, based on – among other significant characteristics – the laying of eggs in a compound structure called an ootheca. The origin of the Dictyoptera and the currently recognized taxa within is, however, a controversial topic among entomologists. This has resulted from disparities in the divergence age estimates obtained from phylogenetic analyses based on molecular data together with the limited and controversial fossil evidence attributable to these groups. Here, we report two new oothecae ichnospecies found in a Carnian (237 to 227 mya. lowermost Upper Triassic) deposit from Argentina. Morphological comparisons and Scanning Electron Microscope and X‐ray Energy Dispersive Spectroscopy analyses of fossil and extant oothecae of mantises and cockroaches were performed in an attempt to solve their systematic placement within Dictyoptera and fossil allies, such as †Alienoptera. In addition to being the earliest known record of oothecae, this discovery moves the origin of this specialized reproductive strategy back by 100 million years. As direct fossil evidence, these specimens provide an important calibration and reference point that can inform future research on the origins and timing of diversification of the Dictyoptera.

Late Paleozoic–Early Mesozoic Insects: State of the Art on Paleoentomological Studies in Southern South America

“…, 7) (Lara & Lukashevich, 2013;Lara et al, , 2015Lara et al, , 2019aLara et al, , 2019bLara et al, , 2023Lara, 2016;Lara & Aristov, 2016;Lara & Wang, 2016;Lara & Bashkuev, 2020;Cariglino et al, 2021). Besides the numerous first taxonomic mentions of insect taxa at various levels (i.e., Order, Family, Genus and species) for South America, among some of the most remarkable findings are the largest collection of scytinopterid hemipterans (Lara, 2016;Wang et al, 2018;Lara et al, 2022Lara et al, , 2023; insect nymphs and larvae (Lara et al, 2019b); the earliest dipterans (Hennigmatidae, Lara & Lukashevich, 2013) and hymenopterans (Xyelidae, ; the first record of Eoscarterellidae (Hemiptera), which supports a Gondwanan origin for the family (Lara & Wang, 2016); the first record of adult grylloblattids (Geinitziidae, Lara & Aristov, 2017); and the earliest record of fossil insect oothecae (Dictyoptera) (Cariglino et al, 2020).…”

“…Besides the numerous first taxonomic mentions of insect taxa at various levels ( i.e. , Order, Family, Genus and species) for South America, among some of the most remarkable findings are the largest collection of scytinopterid hemipterans (Lara, 2016; Wang et al , 2018; Lara et al , 2022, 2023); insect nymphs and larvae (Lara et al , 2019b); the earliest dipterans (Hennigmatidae, Lara & Lukashevich, 2013) and hymenopterans (Xyelidae, Lara et al , 2014); the first record of Eoscarterellidae (Hemiptera), which supports a Gondwanan origin for the family (Lara & Wang, 2016); the first record of adult grylloblattids (Geinitziidae, Lara & Aristov, 2017); and the earliest record of fossil insect oothecae (Dictyoptera) (Cariglino et al , 2020). The abundance and diversity of the Potrerillos Formation entomofauna places it as one of the most important Triassic sites in the world, and together with its paleoflora and vertebrate content, opens a wide array of studies, such as those regarding biotic interactions ( e.g.…”