Maastrichtian representatives of the dragonfly family Aeschnidiidae question the entomofaunal turnover of the early Late Cretaceous

Abstract

Gaps in the fossil record are the major challenge for estimations of impacts of crises of biodiversity of the various clades. They can lead to important misinterpretations in the effects of the different events on the fauna and flora. It is especially the case for the end-Cretaceous, which is ‘near the midpoint of a 16-million-year gap in the insect fossil record’ (Schachat & Labandeira, 2021: 111). All the important Cretaceous insect Konzentrat Lagerstätten are before the Turonian. The analysis of Schachat et al. (2019) has reconstructed a massive loss of family-level diversity for the insects at the boundary Cretaceous-Cenozoic, a possible artefact due to this gap. An alternative scenario was that a turnover in the entomofauna occurred during the early Late Cretaceous in relation to the floristic changes of the Albian–Cenomanian (Nel et al., 2018). This turnover would have also affected the aquatic insects through important changes in the freshwater environments (Sinitshenkova & Zherikhin, 1996; Ivanov & Sukatsheva, 2002). The current knowledge on the odonatan fossil record suggests a pronounced turnover with the last records of several major clades during the Cenomanian-Turonian and first records of several modern ones during the same period (Nel et al., 2015). The widespread and very diverse Jurassic-Cretaceous family Aeschnidiidae is among the best examples of such extinctions supposed to have occurred after the Cenomanian, because of the absence of any fossil in younger strata.