Alcântara Formation

The Alcântara Formation is a geological formation in northeastern Brazil whose strata date back to the Cenomanian of the Late Cretaceous.^[1]

Alcântara Formation
Stratigraphic range: Cenomanian
Type	Geological formation
Unit of	Itapecuru Group
Underlies	Cujupe Formation
Overlies	Undifferentiated unit
Thickness	30–35 m (98–115 ft)
Lithology
Primary	Sandstone
Other	Claystone, conglomerate
Location
Coordinates	2.5°S 44.5°W / -2.5; -44.5
Approximate paleocoordinates	9.4°S 19.3°W / -9.4; -19.3
Region	Maranhão
Country	Brazil
Extent	São Luís-Grajaú Basin
Type section
Named for	Alcântara (city)
Named by	Rossetti & Truckenbrodt
Year defined	1997
Alcântara Formation (Brazil)

Fossil content

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.

Dinosaurs

Sauropods

Sauropods of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Itapeuasaurus[2]	I. cajapioensis	Itapeua beach			A rebbachisaurid sauropod
cf. Limaysaurus[3]	L. tessonei	Laje do Coringa, Cajual Island		Vertebrae	A rebbachisaurid sauropod
cf. Malawisaurus?[4][5]	M. sp.	Laje do Coringa, Cajual Island		Tooth	A tooth similar to Malawisaurus
Sauropoda indet.[5]	Indeterminate	Laje do Coringa, Cajual Island		Teeth	May belong to a titanosaurian or a diplodocoid rebbachisaurid
Titanosauria indet.[5]	Indeterminate	Laje do Coringa, Cajual Island		Vertebrae and an osteoderm	A titanosaurian sauropod

Theropods

Theropods of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Abelisauridae indet.[6]	Indeterminate	Laje do Coringa, Cajual Island		Two shed tooth crowns	A abelisaurid theropod
Carcharodontosauridae indet.[7]	Indeterminate	Laje do Coringa, Cajual Island		Teeth	A carcharodontosaurid theropod
Dromaeosauridae indet.[5]	Indeterminate	Laje do Coringa, Cajual Island		Teeth	Possible member of Velociraptorinae
Noasauridae indet.[8]	Indeterminate	Laje do Coringa, Cajual Island		Nine teeth	A noasaurid theropod; closely related to Masiakasaurus.
Oxalaia[9]	O. quilombensis	Laje do Coringa, Cajual Island		Fused premaxillae; isolated and incomplete left maxilla (both heavily damaged from the National Museum of Brazil fire)	A spinosaurid theropod which may be synonymus with Spinosaurus itself.[10] However, this has been disputed.[11]
Sigilmassasaurus[5]	S. brevicollis	Laje do Coringa, Cajual Island		Two caudal vertebrae	Referral to Sigilmassasaurus was based on similarity to presumed caudal vertebrae of the genus from the Kem Kem Group. However, the 2022 study noted that these specimens are indeterminate spinosaurids, most likely belonging to Oxalaia considering the geographical and geological context.[12]
Spinosauridae indet.[13]	Indeterminate	Laje do Coringa, Cajual Island		Teeth	A spinosaurid theropod different from Oxalaia.
Unenlagiinae[14]	Indeterminate	Laje do Coringa, Cajual Island, São Luís-Grajaú Basin		Teeth	A dromaeosaurid theropod

Pterosauria

Pterosaurs of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Anhangueridae indet.[5]	Indeterminate	Laje do Coringa, Cajual Island		Teeth	A anhanguerid pterosaur

Crocodylomorphs

Crocodylomorphs of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Candidodon[5]	C. itapecuruense	Laje do Coringa, Cajual Island		Teeth	A notosuchian
Coringasuchus[15]	C. anisodontis	Laje do Coringa, Cajual Island		Partial right dentary	A notosuchian

Turtles

Turtles of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Pelomedusoides indet.[5]	Indeterminate	Laje do Coringa, Cajual Island		Incomplete carapace

Squamates

Squamates of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Seismophis[16]	S. septentrionalis	Laje do Coringa, Cajual Island		Vertebrae	A snake

Mosasaurs

Mosasaurs of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Carinodens[5]	C. fraasi	Laje do Coringa, Cajual Island			A globidensin mosasaurine; originally known as Globidens fraasi

Fish

Fishes of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Aegyptobatus[17]	A. kuehnei	Laje de Coringa, Cajual Island			A distobatid hybodont
Arganodus[5]	A. tiguidiensis	Laje do Coringa, Cajual Island		Dental plates	A ceratodontid lungfish
Atlanticopristis[18]	A. equatorialis	Falésia do Sismito and Laje do Coringa, Cajual Island		Fourteen denticle specimens (two complete)	A sclerorhynchoid
Bartschichthys[5]	B. sp.	Laje do Coringa, Cajual Island		Spines	A cladistian
Ceratodus[5]	C. brasiliensis	Laje do Coringa, Cajual Island		Dental plates	A ceratodontid lungfish
	C. humei
Equinoxiodus[5]	E. alcantarensis[19]	Laje do Coringa, Cajual Island		One complete and eight incomplete tooth plates	A neoceatodontid lungfish
	E. schuitzei[20]
Lepidotes[5]	L. sp.	Laje do Coringa, Cajual Island		Mineralized scales	A lepidotid fish.
Lepisosteidae Indet.[21]	Indeterminate	Laje do Coringa, Cajual Island
Mawsonia[22]	M. gigas	Laje do Coringa, Cajual Island		Palato-quadrate and post-parietal cranial material	A mawsoniid coelacanth.
Myliobatis[5]	M. dixoni	Laje do Coringa, Cajual Island			A myliobatid eagle ray
Onchopristis	cf. O. numida[23]	Laje do Coringa, Cajual Island		Rostral teeth	A sclerorhynchoid
Pycnodontiformes indet.[5]	Indeterminate	Laje do Coringa, Cajual Island		Dental plate and teeth
Stephanodus[5]	S. sp.	Laje do Coringa, Cajual Island		Pharyngeal teeth	A pycnodontid fish
Tribodus[5]	T. limae	Laje do Coringa, Cajual Island		Dorsal spines	A hybodont shark