High fidelity preservation of fossil insects from the Crato Formation (Lower Cretaceous) of Brazil

Abstract

Fossil insects from the Lower Cretaceous (Aptian) Crato Formation of northeast Brazil are preserved as goethite replacements in laminated limestones of lacustro-lagoonal origin. They display remarkable degrees of morphological detail down to the macro molecular level in some examples. We document the fidelity of preservation and reveal a remarkable variety of morphological detail comparable in some instances with that found in amber inclusions.

Deciphering the preservation of fossil insects: a case study from the Crato Member, Early Cretaceous of Brazil

“…Martínez-Delclòs, Briggs & Peñalver (2004) have pointed out the common association of insect soft-tissue preservation with fine-grained laminated carbonates, which is indeed the case of the Crato Member. Whilst previous studies have considered the preservation of these organisms (Heimhofer & Martill, 2007; Menon & Martill, 2007; Delgado et al, 2014; Barling et al, 2015), microtextural and geochemical analyses have not been performed, nor has a detailed taphonomic model been proposed Based on imaging, geochemical, and mineralogical analyses, this paper presents data that supports the central role of microorganisms in the fossilisation of the Crato Member insects. We propose a preservational pathway able to predict interconnections between geobiological and taphonomic processes operating in the exceptional preservation of these insects, which have yielded 3D replicas with mineralised internal soft tissues.…”

“…Within the palaeolacustrine setting of the Crato Member, several insect groups display exceptional preservation of non-biomineralised tissues on a micron-scale as well as gross morphological features (Delgado, 2014; Barling et al, 2015). Martínez-Delclòs, Briggs & Peñalver (2004) have pointed out the common association of insect soft-tissue preservation with fine-grained laminated carbonates, which is indeed the case of the Crato Member.…”

<strong>Microtomographic study on the anatomy of adult male eyes of two mayfly species</strong>

“…Most Ephemeroptera, and insects in general, possess hexagonal ommatidia. However, in mayflies of the family Leptophlebiidae, the existence of square faceted ommatidia have been reported (Gillies 1951;Edmunds 1963;Peters & Edmunds Jr 1970;Barling et al 2014;Horridge & Mclean 1978;Savage 1986;Peters & Gillies 1995;Godunko et al 2015) Material and methods Adults of two mayfly species, collected in southern Spain, and having different types of developed eyes in males, were studied: Epeorus assimilis Eaton, 1885, a heptageniid species with well-developed, but non turbinate eyes and Cloeon simile Eaton 1870, a common baetid species with well-developed turbinate eyes (Fig.1). To get volume rendering images, we followed the procedure schematically explained in Fig.…”

Taxonomic diversity of cockroach assemblages (Blattaria, Insecta) of the Aptian Crato Formation (Cretaceous, NE Brazil)

“…More than 350 species representing over 20 insect orders have been described, with terrestrial adult orthopterans, hemipterans, ephemeropterans and odonatas (Menon & Martill 2007;Bechly 2007 b;Heads & Leuzinger 2011;Barling et al 2015). Three mantises and six termite species have been described so far (Bechly 2007 c;Hörnig et al 2013;Lee 2014), but about a quarter of the arthropod specimens from the Crato Formation are cockroaches (Bechly 1998;Menon & Martill 2007;Dittman et al 2015;n = 3,651), with only dozens of species described.…”