Adamantina Formation

Adamantina Formation
Stratigraphic range: Late Coniacian-Early Maastrichtian 87.8–68 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Bauru Group
Underlies	Uberaba Formation
Overlies	Santo Anastacio, Caiuá & Araçatuba Formations
Lithology
Primary	Sandstone, calcrete
Other	Mudstone, siltstone, conglomerate, coal
Location
Coordinates	21°36′S 50°06′W / 21.6°S 50.1°W / -21.6; -50.1
Approximate paleocoordinates	25°48′S 33°06′W / 25.8°S 33.1°W / -25.8; -33.1
Region	São Paulo
Country	Brazil
Extent	Bauru Basin, Paraná Basin
Type section
Named for	Adamantina
Adamantina Formation (Brazil)

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.

Dinosaur remains are among the fossils that have been recovered from the Adamantina Formation.^[1] According to some studies,^[2][3][4][5] 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.^[6][7]

More recent studies lean into the latter category^[8] and an unpublished article abstract revealed at the Society of Vertebrate Paleontology in 2017 also argues that the Allen Formation, Loncoche, and Los Alamitos Formation are all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.^[9] A zircon was found dating to 87.8 Ma, so this represents a maximum age.^[10]

During the Early Jurassic, the supercontinent Pangea started to drift apart due to the breakup of Gondwana and Laurasia.^[11] 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.^[12] 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.^[12]

The Bauru Basin is a trough that, as Miall (1990) argues,^[13] evolved due to “thermo-mechanical subsidence” during the Late Cretaceous, probably due to the breakup of Africa and India.^[11] The sediments reach a thickness of up to ~300 m and consist mainly of siliciclastic sediments.^[14] The Bauru Group can be subdivided into five different formations ^{[12][15][16][17]} 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.^[12]

Crocodylomorphs of the Adamantina Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Adamantinasuchus[18]	A. navae			Six specimens and several isolated bone remains.	A notosuchian
Aphaurosuchus[19]	A. kaiju			Skull elements and teeth.	A baurusuchid.
Armadillosuchus[20]	A. arrudai				A notosuchian
Barreirosuchus[21]	B. franciscoi				A trematochampsid
Baurusuchus	B. albertoi[7]				A baurusuchid
	B. pachechoi[22]				A baurusuchid
	B. salgadoensis[22]				A baurusuchid
Brasileosaurus[22]	B. pachecoi[22]
Caipirasuchus[23]	C. paulistanus				A sphagesaurid
Campinasuchus[5]	C. dinizi				A baurusuchid
Caryonosuchus[24]	C. pricei				A sphagesaurid
Roxochampsa[25]	R. paulistanus			Several teeth, splenials, and dentaries.	a member of itasuchidae, previously known as "Goniopholis" paulistanus
Mariliasuchus	M. amarali[22]			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 notosuchian
	M. robustus[26]				A notosuchian
Montealtosuchus[27]	M. arrudacamposi				A peirosaurid
Morrinhosuchus[28]	M. luziae				A notosuchian
Sphagesaurus	S. huenei[22]				A sphagesaurid
	S. montealtensis[6]				A sphagesaurid
Stratiotosuchus[18]	S. maxhechti				A baurusuchid

Indeterminate dinosaur remains are known from the formation.^[29]

Sauropods of the Adamantina Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Adamantisaurus[30]	A. mezzalirai				A titanosaur.
Arrudatitan[31]	A. maximus			A single partially articulated skeleton.	A titanosaur.
Antarctosaurus	A. brasiliensis			Postcranial remains.[32]	A titanosaur.
Brasilotitan	B. nemophagus	Raposo Tavares.		A partial skeleton and dentition.	A titanosaur.
Gondwanatitan	G. faustoi			Partial postcranial skeleton.[33]	A titanosaur.
Maxakalisaurus[34]	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 titanosaur.

Crocodylomorphs of the Adamantina Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Boipeba	B. tayasuensis			A single precloacal vertebra	A large, primitive blind snake

Eutheria incertae sedis, Brasilestes (tribosphenida incertae sedis),^[41] gondwanatheres and meridiolestidans.^[42]

• Geologic formations of Brazil
• List of dinosaur-bearing rock formations
• Paleontological sites of Brazil
• Asencio Formation