Fossils have been found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina that date back to the Norian stage of the Late Triassic, making it one of the last "rauisuchians" to have existed before the order became extinct at the end of the Triassic.

[4][5] This would make Fasolasuchus the largest terrestrial predator to have ever existed save for large theropods, surpassing the Cenozoic Barinasuchus, the "rauisuchian" counterpart Saurosuchus at 7 metres (23 ft), and many medium sized theropods as large as Ceratosaurus.

[6][7][8] Like Saurosuchus, it had only a single row of caudal osteoderms, unusual among "rauisuchians".

[9] It also had a hyposphene-hypantrum articulation that gave the vertebral column extra rigidity.

[10][11] Cladogram after the analysis of Nesbitt (2011):[12] Poposauroidea Prestosuchus Saurosuchus Batrachotomus Fasolasuchus Rauisuchidae Crocodylomorpha A study on bone microstructure determined that Fasolasuchus had a relatively fast growth rate, similar to most other "rauisuchians", with the exception of Prestosuchus.