# Adamantina Formation

The Adamantina Formation is a geological formation in the Bauru Basin of western São Paulo state, in southeastern Brazil.
Its strata date back to the Late Cretaceous epoch of the Cretaceous Period, during the Mesozoic Era. The formation is part of the Bauru Group in the northeastern Paraná Basin.

## Geology

Dinosaur remains are among the fossils that have been recovered from the Adamantina Formation. According to some studies, the Adamantina Formation dates from the Turonian to the Santonian stage (90-83.5 million years ago) of the late Cretaceous, other studies have found a much younger age - Campanian to Maastrichtian (83.5-66 million years ago) of the late Cretaceous.
More recent studies lean into the latter category and an unpublished article abstract revealed at the Society of Vertebrate Paleontology in 2017 also argues that the Allen Formation, Loncoche, and Los Alamitos Formation are all contemporaries and are no later than 72.1Ma in age. A zircon was found dating to 87.8 Ma, so this represents a maximum age.

### Geological setting

During the Early Jurassic, the supercontinent Pangea started to drift apart due to the breakup of Gondwana and Laurasia. The breakup of Gondwana caused the formation of the large Parana Basin. This basin has a size of ~1,100,000km2 and can be found not only in Brazil but also in Paraguay, Uruguay, and Argentina. The separation of the supercontinent and the breakup of Brazil and Africa was accompanied by volcanism that caused large eruptions of flood basalts. These volcanic rocks formed the Serra Geral Formation which underlies the deposits of the Bauru Group.
The Bauru Basin is a trough that, as Miall (1990) argues, evolved due to “thermo-mechanical subsidence” during the Late Cretaceous, probably due to the breakup of Africa and India. The sediments reach a thickness of up to ~300 m and consist mainly of siliciclastic sediments. The Bauru Group can be subdivided into five different formations from bottom to top: Caiua, Santo Anastacio, Adamantina, and Uberaba. Not all formations are equally well represented in the different states and differences occur according their sedimentary composition and therefore also in their naming.

## Vertebrate paleofauna
### Crocodylomorphs

| 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. |
Crocodylomorphs of the Adamantina Formation :
| Genus | Species | Material | Notes |
| Adamantinasuchus | A. navae | Six specimens and several isolated bone remains. | A zhiphosuchian notosuhian |
| Aphaurosuchus | A. kaiju | Skull elements and teeth. | A baurusuchine baurusuchid |
| Armadillosuchus | A. arrudai | | A ziphosuchian notosuchian |
| Barreirosuchus | B. franciscoi | | A peirosaurid notosuchia |
| Baurusuchus | B. albertoi | | A baurusuchine baurusuchid |
| Baurusuchus | B. pachechoi | | A baurusuchine baurusuchid |
| Baurusuchus | B. salgadoensis | | A baurusuchine baurusuchid |
| Brasileosaurus | B. pachecoi | | A notosuchid notosuchian |
| Campinasuchus | C. dinizi | | A pissarrachampsine baurusuchid |
| Caipirasuchus | C. catanduvensis | | A sphagesaurid notosuchian |
| Caipirasuchus | C. paulistanus | | A sphagesaurid notosuchian |
| Caryonosuchus | C. pricei | | A sphagesaurid notosuchian |
| Epoidesuchus | E. tavaresae. | | A peirosaurid notosuchian |
| Mariliasuchus | M. amarali | Very common. Several specimens - juvenile and adults – with skulls articulated to skeletons, and many isolated materials. Eggs clutches, eggshells, and coprolites were found also. | A notosuchid notosuchian |
| Mariliasuchus | M. robustus | | A notosuchid notosuchian |
| Montealtosuchus | M. arrudacamposi | | A peirosaurid notosuchian |
| Morrinhosuchus | M. luziae | | A sphagesaurid notosuchian |
| Roxochampsa | R. paulistanus | Several teeth, splenials, and dentaries. | A peirosaurid notosuchian |
| Sphagesaurus | S. huenei | | A sphagesaurid notosuchian |
| Sphagesaurus | S. montealtensis | | A sphagesaurid notosuchian |
| Stratiotosuchus | S. maxhechti | | A baurusuchine baurusuchid |

### Dinosaurs

Indeterminate dinosaur remains are known from the formation.

#### Sauropods

Sauropods of the Adamantina Formation :
| Genus | Species | Location | Material | Notes |
| Adamantisaurus | A. mezzalirai | | | A lithostrotian titanosaurian |
| Arrudatitan | A. maximus | | A single partially articulated skeleton. | A aeolosaurin titanosaurian |
| Antarctosaurus | A. brasiliensis | | Postcranial remains. | A colossosaurian titanosaurian |
| Brasilotitan | B. nemophagus | Raposo Tavares. | A partial skeleton and dentition. | A lithostrotian titanosaurian |
| Gondwanatitan | G. faustoi | | Partial postcranial skeleton. | A lithostrotian titanosaurian |
| Maxakalisaurus | M. topai | | A fragmentary right maxilla with teeth, twelve cervical vertebrae and some cervical ribs, seven dorsal vertebrae and some dorsal ribs, a neural spine and centrum from the sacrum, six caudal vertebrae, some haemal arches, pieces of the scapulae, both sternal plates, part of the left ischium, both humeri, two metacarpals, part of the fibula, an osteoderm, and some unidentified piece | A lithostrotian titanosaurian |

#### Theropods

Theropods of the Adamantina Formation :
| Genus | Species | Material | Notes |
| Abelisauridae Indet. | Indeterminate | Fragment of right premaxilla and a tooth | |
| Enantiornithes indet. | Indeterminate | Near complete jaws and skulls | |
| Navaornis | N. hesitate | Complete skull and well preserved skeleton | A enantiornithine bird |
| Noasauridae Indet. | Indeterminate | | |
| Unenlagiinae indet. | Indeterminate | A single dorsal vertebra | |

### Squamates

Squamates of the Adamantina Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Boipeba | B. tayasuensis | | | A single precloacal vertebra | A large, primitive blind snake | |
| Brasiliguana | B. prudentis | | | A maxilla | An Iguanian | |

### Amphibians

Amphibians of the Adamantina Formation :
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Baurubatrachus | B. santosdoroi | Near Catanduva city, São Paulo. | | Remains of two individuals. | A frog. | |
| Mariliabatrachus | M. navai | | | | A frog. | |

### Turtles

Turtle of the Adamantina Formation :
| Genus | Species | Notes |
| Bauruemys | B. brasilensis | A podocnemidoid side-necked turtle |
| Roxochelys | R. wanderleyi | A podocnemididoid side-necked turtle |
| Yuraramirim | Y. montealtensis | A peiropemydid side-necked turtle |

### Fish

Fishes of the Adamantina Formation :
| Genus | Species | Notes |
| Amiidae Indet. | Indeterminate | |
| Atractosteus | A. sp. | A gar |
| Britosteus | B. amarildoi | A gar |
| Dipnoi Indet. | Indeterminate | |
| Lepisosteidae | Indeterminate, previously described as "Lepisosteus cominatoi" | A gar |

### Mammals

Mammals of the Adamantina Formation :
| Genus | Species | Notes |
| Eutheria Indet. | Indeterminate | |
| Brasilestes | B. stardusti | A tribosphenic mammal |
| Gondwanatheria Indet. | Indeterminate | |
| Meridiolestida Indet. | Indeterminate | |