The Pastos Bons Formation is a Late Jurassic (Oxfordian to Kimmeridgian) geologic formation of the Parnaíba Basin in Maranhão, northeastern Brazil. The formation forms part of the sag phase of the basin. It overlies the Sardinha Formation and is overlain by the Mosquito Formation. The fluvial to lacustrine sandstones and shales have provided fossils of a coelacanth fish, Parnaibaia maranhaoensis and a paralligatorid named after the formation, Batrachomimus pastosbonensis.

The following fossils were reported from the formation:

• Reptiles
  • Batrachomimus pastosbonensis
• Fish
  • Lophionotus parnaibensis
  • Parnaibaia maranhaoensis

• Takutu Formation, contemporaneous formation of northern Brazil and Guyana

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