Carboniferous Argentina

Megarachne is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Megarachne have been discovered in deposits of Late Carboniferous age, from the Gzhelian stage, in the Bajo de Véliz Formation of San Luis, Argentina. The fossils of the single and type species M. servinei have been recovered from deposits that had once been a freshwater environment. The genus name comes from Ancient Greek μέγας (mégas), meaning "great", and ἀράχνη (aráchnē), meaning "spider", and thus, "great spider"; because the fossil was misidentified as a large, prehistoric spider.

Rhadinichthys is an extinct genus of prehistoric bony fish. It is known from several species that lived in the Late Devonian epoch, the Carboniferous period and the Cisuralian epoch (early Permian) in what is now Europe, South Africa, and North and South America. Some isolated scales from the Cisuralian of Europe (Belgium, France, Russia) were also referred to this genus.