Exceptionally well-preserved orthopteran proventriculi from the Cretaceous Crato Formation of Brazil

Abstract

The Crato Formation (Santana Group, Araripe Basin, Brazil) bears a high abundance of fossils in exceptional state of preservation, with insects from the order Orthoptera standing out. However, so far, few studies have explored their preserved inner organs in detail. Here, we provide the first detailed description of fossilized proventriculi from nine Grylloidea (Orthoptera: Ensifera) specimens of the Crato Formation. In all analyzed specimens, the external cuticle of the abdomen is cracked exposing the proventriculi, which are preserved as a tridimensional organ with a globular body and a tubular neck, similar to that of modern crickets. However, in the globular region of all fossils analyzed there are 9–12 rows of parallel divisions, differing from the modern crickets which have, more frequently, six. SEM images of two specimens revealed the exceptional preservation of internal median teeth, folds, and microvilli texture preserved in the organ.