# Bajo de la Carpa Formation

The Bajo de la Carpa Formation is a geologic formation of the Neuquén Basin that crops out in northern Patagonia, in the provinces of Río Negro and Neuquén, Argentina. It is the oldest of two formations belonging to the Río Colorado Subgroup within the Neuquén Group. Formerly, that subgroup was treated as a formation, and the Bajo de la Carpa Formation was known as the Bajo de la Carpa Member.
At its base, this formation conformably overlies the Plottier Formation of the older Río Neuquén Subgroup, and it is in turn overlain by the Anacleto Formation, the youngest and uppermost formation of the Neuquén Group.
The Bajo de la Carpa Formation can reach 150 metres (490 ft) in thickness in some locations, and consists mainly of sandstones of various colors, all of fluvial origin, with thin layers of mudstone and siltstone in between. Geological features such as geodes, chemical nodules, impressions of raindrops, and paleosols (fossil soils) are commonly found in this formation as well.

## Fossil content
### Reptiles

Reptiles reported from the Bajo de la Carpa Formation :
| Genus | Species | Notes |
| Lomalatachelys | L. neuquina | A snake-necked turtle |
| Dinilysia | D. patagonica | A Snake |
| Paleochelco | P. occultato | A lizard |
| Podocnemidoidea | Indeterminate. | |
Small nests with eggs inside, found in this formation, probably belonged to the bird Neuquenornis. Fossil wasp nests have also been found in these rocks.

#### Crocodylomorphs

Crocodylomorphs reported from the Bajo de la Carpa Formation :
| Genus | Species | Material |
| Barrosasuchus | B. neuquenianus | |
| Comahuesuchus | C. brachybuccalis | |
| Cynodontosuchus | C. rothi | |
| Lomasuchus | L. palpebrosus. | |
| Gasparinisuchus | G. peirosauroides | |
| Kinesuchus | K. overoi | |
| Neuquensuchus | N. universitas | |
| Notosuchus | N. lepidus | |
| Notosuchus | N. terrestris | |
| Peirosaurus | P. torminni | A fragmentary skull and a partial postcranial skeleton. |

### Fish

Fish reported from the Bajo de la Carpa Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Rinconodus | R. salvadori | | | | A ceratodontid lungfish | |

### Dinosaurs
#### Ornithischians

Ornithischians reported from the Bajo de la Carpa Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Ankylosauria | Indetermidate. | | | | | |
| Mahuidacursor | M. lipanglef | | | | An ornithopod. | |

#### Sauropods

Sauropods reported from the Bajo de la Carpa Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes |
| Bonitasaura | B. salgadoi | | | A partial sub-adult skeleton with a lower jaw, a partial vertebrae series, and limb bones. | A titanosaur. |
| Inawentu | I. oslatus | Rincón de los Sauces. | | A partially articulated skeleton, including a nearly complete skull, Several vertebrae from the atlas to the end of the sacrum, and both ilia | A titanosaur. |
| Overosaurus | O. paradasorum | | Upper | A fully articulated vertebral series consists of rib bones, dorsals, and ilium. | A titanosaur. |
| Rinconsaurus | R. caudamirus | Rincón de los Sauces. | Lower. | The fossil remains included vertebrae, limb bones, scapula, hip bones (pubis, ilium, and ischium) and several ribs. | A titanosaur. |
| Traukutitan | T. eocaudata | Sitio Trauku. | Lower | A partial semi-articulated skeleton including both thigh bones and thirteen vertebrae from the anterior and middle tail. | A titanosaur. |

#### Theropods

Theropods reported from the Bajo de la Carpa Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes |
| Achillesaurus | A. manazzonei | | Upper | A partial skeleton consists of a sacral vertebra, four tail vertebrae, part of the left thighbone, shin, and foot, and the left ilium. | An alvarezsaurid. |
| Alvarezsaurus | A. calvoi | | | | An alvarezsaurid. |
| Diuqin | D. lechiguanae | "the isthmus between the southeast coast of Lago Barreales and the northwest coast of Lago Mari Menuco" | | A fragmentary but associated partial skeleton | An unenlagiine. |
| Llukalkan | L. aliocranianus | La Invernada site. | | A partial skull. | An abelisaur. |
| Neuquenornis | N. volans | | Upper | A skull and a partial postcranial remains. | A enantiornithine bird. |
| Patagopteryx | P. eferrariisi | | Upper | | The oldest known flightless bird. |
| Tratayenia | T. rosalesi | | | A well-preserved partial skeleton | A megaraptoran theropod. |
| Velocisaurus | V. unicus | | | | A noasaur. |
| Viavenator | V. exxoni | | | | An abelisaur. |