The role of microbial mats in the exquisite preservation of Aptian insect fossils from the Crato Lagersta euro tte, Brazil

The insect fossils recorded in the lithographic limestones of the Crato Formation (Aptian of the Araripe Basin, Brazil) have a high degree of morphological fidelity of external and internal anatomical features, including cuticular remains, muscles and organs. The main factor for this exquisite preservation is considered to be the influence of microbial mats in the fossilization process. Petrographic and scanning electron microscope analysis with coupled x-ray spectroscopy (SEM/EDS) showed direct and indirect microbial features associated with the microfabric of the orthopteran insect fossils. We propose a four steps model for insect fossil preservation, with the capture, protection, creation of the microbial sarcophagus, and mineralization of the organic remains mediated by microbial mats. The confluence of morphological and taphonomic data indicates possible climatic variations on the Aptian of the Araripe Basin, with the exquisitely preserved insect fossils associated with favorable environmental conditions for the installation of microbial mats on the lacustrine substrate. 0 2021 Elsevier Ltd. All rights reserved.

Automated summary

Insect fossils in the lithographic limestones of the Crato Formation in the Araripe Basin of Brazil show a high degree of morphological fidelity due to the influence of microbial mats. Petrographic and SEM/EDS analysis revealed microbial features associated with the insect fossils. A four-step model was proposed for insect fossil preservation, involving capture, protection, creation of microbial sarcophagus, and mineralization by microbial mats. The confluence of morphological and taphonomic data suggests possible climatic variations in the Aptian of the Araripe Basin.