Artigo | Reproductive organs of a Grylloidea fossil from the Cretaceous Araripe Basin, Brazil

 

The Crato Formation, an Early Cretaceous lacustrine Lagerstätte in Northeastern Brazil, is noteworthy for soft-tissue fossilization. This unit records an abundant and diverse palaeoentomofauna, which preserve external and internal elements, including organs and delicate tissues. Here, we report the oldest and only known fossilized insect ovary fragments, found in the laminated limestone of the Crato Formation, Araripe Basin. It is a female Baissogryllidae, an extinct lineage of true crickets (Grylloidea). Dissection of the extant cricket, Endecous (Notendecous) onthophagus (Berg, 1891), facilitated accurate morphological and morphometric comparisons, enhancing our interpretation of the fossil structures. Besides the ovaries, dozens of elliptical microelements, resembling fossilized "eggs," were found in the female abdomen. These structures are significantly smaller than the mature oocytes of E. (N.) onthophagus or even early-stage oocytes. It remains open whether these microelements represent immature baissogryllid oocytes or if Cretaceous cricket eggs were inherently smaller. Alternatively, this could be a preservation artefact. Taphonomic signatures suggest that this ancient Grylloidea lived close to a lacustrine environment, likely using lake margins for oviposition. Despite the open wings indicating death near the depositional environment, the straighter abdomen and ovipositor suggest that the cricket was not ovipositing at its time of death.