# Cerro Fortaleza Formation

The Cerro Fortaleza Formation, in older literature described as Pari Aike Formation, is a Late Cretaceous geologic formation of Campanian to Maastrichtian age (although it has formerly been reported to be Cenomanian to Santonian) of the Austral Basin in southern Patagonia, Argentina.

## Description

The sandstones of the formation were deposited in a fluvial environment. The formation has an estimated thickness of 460 metres (1,510 ft) and overlies the Anita Formation, while it is overlain by the La Irene Formation. These formations are considered Campanian and Maastrichtian in age, respectively, making the Cerro Fortaleza Formation aged between them.

## Paleobiota

The giant titanosaurs Puertasaurus and Dreadnoughtus, the megaraptoran Orkoraptor, the berthasaurid Austrocheirus isasii, and the ornithopod Talenkauen have been recovered from the formation alongside turtles and crocodiles.

### Dinosaurs

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |

#### Ornithischians

Ornithischians of the Cerro Fortaleza Formation :
| Taxa | Species | Locality | Stratigraphic unit | Material | Notes |
| Ankylosauria | indet. | | | Small-sized isolated osteoderms. | |
| Iguanodontoidea | indet. | | | One incomplete maxillary tooth crown. | |
| Ornithopoda | indet. | | | Two isolated caudal centra. | |
| Talenkauen | T. santacrucensis | Corro Los Hornos near Lake Viedma. | Upper | A partial articulated skeleton with exception of the rear part of the skull, the tail, and the hands. | An elasmarian ornithopod. |

#### Sauropods

Sauropods of the Cerro Fortaleza Formation :
| Taxa | Species | Locality | Stratigraphic unit | Material | Notes | Images |
| Clasmodosaurus | C. spatula | Lago Viedma | | Two incomplete teeth. | A titanosaur | Dreadnoughtus Puertasaurus |
| Clasmodosaurus | Indeterminate | | | 32 isolated teeth. | A titanosaur | Dreadnoughtus Puertasaurus |
| Dreadnoughtus | D. schrani | Rio La Leona Valley, | Upper | Four incomplete proximal caudals and incomplete left astragalus. | A titanosaur. | Dreadnoughtus Puertasaurus |
| Puertasaurus | P. reuili | Cerros Los Hornos, La Leona. | Upper | A holotype based on four disarticulated vertebrae, specifically one cervical, one dorsal, and two caudal vertebrae. | A titanosaur. | Dreadnoughtus Puertasaurus |

#### Theropods

Theropods of the Cerro Fortaleza Formation :
| Taxa | Species | Locality | Stratigraphic unit | Material | Notes | Images |
| Abelisauridae | indet. | | | An incomplete ziphodont tooth. | | Austrocheirus isasii Orkoraptor burkei |
| Austrocheirus | A. isasii | Hoyada Arroyo Seco. | Upper | An incomplete right ulna | An ceratosaurian theropod. | Austrocheirus isasii Orkoraptor burkei |
| Orkoraptor | O. burkei | Cerro Los Hornos. | Upper | Several isolated teeth, including two anteriormost, probably premaxillary teeth, left manual phalanx I-1, right, nearly complete fibula, and right ungual. | A megaraptoran | Austrocheirus isasii Orkoraptor burkei |

### Fish

Fish of the Cerro Fortaleza Formation :
| Taxa | Species | Locality | Stratigraphic unit | Material | Notes | Images |
| Atlantoceratodus | A. iheringi | Cerro Los Hornos and Hoyada Arroyo Seco. | | Four lower tooth plates, one lower tooth plate attached to a partial mandibular bone and four upper tooth plates. | A lungfish. | |