Preservation and Taphonomy of Fossil Insects from the Earliest Eocene of Denmark

Abstract

Marine sediments of the lowermost Eocene Stolleklint Clay and Fur Formation of north-western Denmark have yielded abundant well-preserved insects. However, despite a long history of research, in-depth information pertaining to preservational modes and taphonomic pathways of these exceptional animal fossils remains scarce. In this paper, we use a combination of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to assess the ultrastructural and molecular composition of three insect fossils: a wasp (Hymenoptera), a damselfly (Odonata) and a pair of beetle elytra (Coleoptera). Our analyses show that all specimens are preserved as organic remnants that originate from the exoskeleton, with the elytra displaying a greater level of morphological fidelity than the other fossils. TEM analysis of the elytra revealed minute features, including a multilayered epicuticle comparable to those nanostructures that generate metallic colors in modern insects. Additionally, ToF-SIMS analyses provided spectral evidence for chemical residues of the pigment eumelanin as part of the cuticular remains. To the best of our knowledge, this is the first occasion where both structural colors and chemical traces of an endogenous pigment have been documented in a single fossil specimen. Overall, our results provide novel insights into the nature of insect body fossils and additionally shed light on exceptionally preserved terrestrial insect faunas found in marine paleoenvironments.

Morphological and organic spectroscopic studies of a 44-million-year-old leaf beetle (Coleoptera: Chrysomelidae) in amber with endogenous remains of chitin

“…Elytron peak frequency (cm − www.nature.com/scientificreports/ Generally, components of the original chitin-protein complex tend to transform into complex geopolymers in fossilized insect cuticle 43,44 . However, spectral results in this study suggest organics left in the cuticle of Baltic 83 consist predominately of degraded endogenous chitin.…”

A Plea for a New Synthesis: From Twentieth-Century Paleobiology to Twenty-First-Century Paleontology and Back Again

“…Also in this case, the choice and use of appropriate technologies (such as mass spectrometry methodology, appropriate databases, etc.) is essential to obtain more data and thus pose new questions on phylogenetic hypotheses [ 49 , 50 , 51 , 52 , 53 , 54 ].…”

Effects of chemical weathering on the exceptional preservation of mineralized insects from the Crato Formation, Cretaceous of Brazil: implications for late diagenesis of fine-grained Lagerstätten deposits

“…For those preserved in lacustrine deposits, diagenesis seems to stand out as the most relevant stage. More and more palaeoentomologists have invested in taphonomic investigations, and most of these studies focus on biostratinomic events and/or early-middle diagenetic processes (Duncan & Briggs, 1996;Zhehikhin, 2002;Martínez-Delclòs et al 2004;Smith et al 2006;Smith & Moe-Hoffman, 2007;McNamara et al 2011McNamara et al , 2012Smith, 2012;Thoene-Henning et al 2012;Wang et al 2012;McNamara, 2013;Pan et al 2014;Greenwalt et al 2015;Anderson & Smith, 2017;Tian et al 2020;Iniesto et al 2021;Heingård et al 2022).…”