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	Early Cenomanian		A rebbachisaurid sauropod; closely related to Demandasaurus darwini.
Limaysaurus[3]	L. tessonei	Laje do Coringa, Cajual Island	Early Cenomanian	Vertebrae	A rebbachisaurid sauropod
Lithostrotia[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian		A lithostrotian titanosaur; closely related to Paralititan stromeri.
Malawisaurus?[5]	M. sp.	Laje do Coringa, Cajual Island	Early Cenomanian	Tooth	Probably Titanosauria indet rather than Malawisaurus?
Sauropoda indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Teeth	May belong to a titanosaurian or a diplodocoid rebbachisaurid
Titanosauria indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Vertebrae	A titanosaurian sauropod; closely related to Aegyptosaurus baharijensis.
Titanosauria indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	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	Early Cenomanian	Two shed tooth crowns	A abelisaurid theropod; closely related to Rugops primus.
Bahariasauridae Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian		A bahariasaurid theropod; closely related to Bahariasaurus ingens.
Carcharodontosauridae Indet.[7]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Teeth	A giant carcharodontosaurid theropod; closely related to Carcharodontosaurus saharicus.
Dromaeosauridae indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Teeth	Possible member of Velociraptorinae
Noasauridae indet. [8]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Nine teeth	A noasaurid theropod; closely related to Masiakasaurus knopfleri.
Oxalaia[9]	O. quilombensis	Laje do Coringa, Cajual Island	Early Cenomanian	Fused premaxillae; isolated and incomplete left maxilla	A spinosaurid theropod which may be synonymus with Spinosaurus itself.[10] However, this has been disputed.[11]
Sigilmassasaurus[4]	S. brevicollis	Laje do Coringa, Cajual Island	Early Cenomanian	Two caudal vertebrae	Referral to Sigilmassasaurus was based on similarity to presumed caudal vertebrae of the genus from the Kem Kem Group. However, these caudal vertebrae have since been separated from the genus, meaning that it is currently impossible to refer any caudal vertebrae to it.
Spinosauridae indet.[12]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Teeth	A spinosaurid theropod different from Oxalaia.
Theropoda indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Claw
Unenlagiinae[13]	Indeterminate	Laje do Coringa, Cajual Island, São Luís-Grajaú Basin	Early Cenomanian	Teeth	A dromaeosaurid theropod; closely related to Buitreraptor gonzalezorum.

Ornithopods

Ornithopods of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Hadrosauriformes Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian		A sail-backed hadrosauriform iguanodontian; closely related to Ouranosaurus nigeriensis.
Parankylosauria Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian		A parankylosaurian ankylosaurian; closely related to Stegouros elengassen.

Pterosauria

Pterosaurs of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Anhangueridae indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanina	Teeth	A anhanguerid pterosaur; closely related to Siroccopteryx moroccensis.
Azhdarchoidea Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian
Tapejaridae Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanina

Crocodylomorphs

Crocodylomorphs of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Aegyptosuchidae Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian
Araripesuchus[4]	A. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A uruguasuchid notosuchian
Crocodylomorpha indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Teeth and osteoderms
Coringasuchus[14]	C. anisodontis	Laje do Coringa, Cajual Island	Early Cenomanian	Partial right lower jaw (dentary)	A ziphosuchian notosuchian; closely related to Libycosuchus brevirostris.
Elosuchus	E. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A pholidosaurid neosuchian
Laganosuchus[4]	L. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A stomatosuchid neosuchian
Mahajangasuchidae Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian		A mahajangasuchid crocodyliform; closely related to Kaprosuchus saharicus.
Stomatosuchidae Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian		A large stomatosuchid neosuchian; closely related to Stomatosuchus inermis.

Turtles

Turtles of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Bothremydidae Indet.[4]	Indeterminate	aje do Coringa, Cajual Island	Early Cenomanian		A bothremydid turtle; closely related to Apertotemporalis baharijensis.
Pelomedusoides indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Incomplete carapace

Plesiosaurs

Plesiosaurs of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Leptocleididae Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian		A leptocloidid plesiosaur; closely related to Leptocleidus capensis.

Squamates

Squamates of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Seismophis[15]	S. septentrionalis	Laje do Coringa, Cajual Island	Early Cenomanian	Vertebrae	A snake
Simoliophiidae Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian		A simoliopiid sea snake; closely retated to Simoliophis lybica.

Fish

Fishes of the Alcântara Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Adrianaichthys[4]	A. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A lepisosteiform fish.
Aegyptobatus[16]	A. kuehnei	Laje do Coringa, Cajual Island	Early Cenomanian	Teeth	A distobatid hybodont.
Aidachar[4]	A. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A member of Ichthyodectiformes
Arganodus[4]	A. tiguidiensis	Laje do Coringa, Cajual Island	Early Cenomanian	Dental plates	A ceratodontid lungfish
Asteracanthus[4]	A. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A hybodont shark.
Atlanticopristis[17]	A. equatorialis	Falésia do Sismito and Laje do Coringa, Cajual Island	Early Cenomanian	Fourteen denticle specimens (two complete)	A sclerorhynchid rajoid; closely related to Onchopristis numida.
Bartschichthys[4]	B. sp.	Laje do Coringa, Cajual Island	Early Cenomanian	Spines	A cladistian.
Bawitius[4]	B. sp	Laje do Coringa, Cajual Island	Early Cenomanian		A giant bichir.
Ceratodus[4]	C. brasiliensis	Laje do Coringa, Cajual Island	Early Cenomanian	Dental plates	A ceratodontid lungfish.
	C. humei
Cretolamna[4]	C. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A mackerel shark.
Equinoxiodus[4]	E. alcantarensis[18]	Laje do Coringa, Cajual Island	Early Cenomanian	One complete and eight incomplete tooth plates	A neoceatodontid lungfish; possibly closely related to Neoceratodus africanus
	E. schuitzei[19]
Lepidotes[4]	L. sp.	Laje do Coringa, Cajual Island	Early Cenomanian	Mineralized scales	A lepidotid fish.
Lepisosteidae Indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian		A gar; closely related to Atractosteus africanus.
Mawsonia[20]	M. gigas	Laje do Coringa, Cajual Island	Early Cenomanian	Palato-quadrate and post-parietal cranial material	A mawsoniid coelacanth.
Myliobatis[4]	M. dixoni	Laje do Coringa, Cajual Island	Early Cenomanian		A myliobatid eagle ray.
Onchopristis[4]	O. numida	Laje do Coringa, Cajual Island	Early Cenomanian	Rostral teeth	A sclerorhynchoid.
Paranogmius[4]	P. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A plethodid fish.
Pycnodontiformes indet.[4]	Indeterminate	Laje do Coringa, Cajual Island	Early Cenomanian	Dental plate and teeth
Retodus[4]	R. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A neoceratodontid lungfish
Squalicorax[4]	S. sp.	Laje do Coringa, Cajual Island	Early Cenomanian		A large crow shark
Stephanodus[4]	S. sp.	Laje do Coringa, Cajual Island	Early Cenomanian	Pharyngeal teeth	A pycnodontid fish.
Tribodus[4]	T. limae	Laje do Coringa, Cajual Island	Early Cenomanian	Dorsal spines	A hybodont shark.

References

1. Rossetti, D.F.; Truckenbrodt, W. (1997). "Revisão estratigráfica para os depósitos do Albiano-Terciário Inferior (?) na Bacia de São Luís (MA), Norte do Brasil". Boletim do Museu Paraense Emílio Goeldi. 9: 29–41.
2. Lindoso, Rafael Matos; Medeiros, Manuel Alfredo Araújo; Carvalho, Ismar de Souza; Pereira, Agostinha Araújo; Mendes, Ighor Dienes; Iori, Fabiano Vidoi; Sousa, Eliane Pinheiro; Arcanjo, Silvia Helena Souza; Silva, Taciane Costa Madeira (July 2019). "A new rebbachisaurid (Sauropoda: Diplodocoidea) from the middle Cretaceous of northern Brazil". Cretaceous Research. 104: 104191. Bibcode:2019CrRes.10404191L. doi:10.1016/j.cretres.2019.104191. ISSN 0195-6671. S2CID 201321631.
3. Medeiros, Manuel Alfredo; Schultz, Cesar Leandro (2004). "Rayososaurus (Sauropoda, Diplodocoidea) no meso-Cretáceo do Norte-Nordeste Brasileiro". Revista Brasileira de Paleontologia. 7 (2): 275–279. doi:10.4072/rbp.2004.2.22.
4. Medeiros, Manuel Alfredo; Lindoso, Rafael Motos; Mendes, Ighor Dienes; Carvalho, Ismar de Souza (2014). "The Cretaceous (Cenomanian) continental record of the Laje do Coringa flagstone (Alcântara Formation), northeastern South America". Journal of South American Earth Sciences. 53: 50–58. Bibcode:2014JSAES..53...50M. doi:10.1016/j.jsames.2014.04.002.
5. Freire, Pedro Carvalho; Medeiros, Manuel Alfredo; Lindoso, Rafael Matos (2007). "Sauropod teeth diversity in the Laje do Coringa fossiliferous site, Eocenomanian of Northeastern Brazil". Paleontologia: Cenários de Vida: 523–532.
6. Marcos A.F. Sales; Isabel A.P. de Oliveira; Cesar L. Schultz (2018). "The oldest abelisaurid record from Brazil and the palaeobiogeographic significance of mid-Cretaceous dinosaur assemblages from northern South America". Palaeogeography, Palaeoclimatology, Palaeoecology. 508: 107–115. Bibcode:2018PPP...508..107S. doi:10.1016/j.palaeo.2018.07.024. S2CID 133650699.
7. Candeiro, C.R.A.; Martinelli, Agustin G. (2005). "Abelisauroidea and Carcharodontosauridae (Theropoda, Dinosauria) in the Cretaceous of South America. Paleogeographical and geocronological implications". Sociedade & Natureza. 17 (33).
8. Lindoso, Rafael Matos; Medeiros, Manuel Alfredo; Carvalho, Ismar de Souza; Marinho, Thiago da Silva (August 2012). "Masiakasaurus-like theropod teeth from the Alcântara Formation, São Luís Basin (Cenomanian), northeastern Brazil". Cretaceous Research. 36: 119–124. Bibcode:2012CrRes..36..119L. doi:10.1016/j.cretres.2012.03.002.
9. Kellner, Alexander W.A.; Azevedeo, Sergio A.K.; Machado, Elaine B.; Carvalho, Luciana B.; Henriques, Deise D.R. (2012). "A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcântara Formation, Cajual Island, Brazil" (PDF). Anais da Academia Brasileira de Ciências. 83 (1): 99–108. doi:10.1590/S0001-37652011000100006. ISSN 0001-3765. PMID 21437377.
10. Smyth, Robert S.H.; Ibrahim, Nizar; Martill, David M. (2020). "Sigilmassasaurus is Spinosaurus: A reappraisal of African spinosaurines". Cretaceous Research. 114: 104520. doi:10.1016/j.cretres.2020.104520.
11. Isasmendi, Erik; Navarro-Lorbés, Pablo; Sáez-Benito, Patxi; Viera, Luis I.; Torices, Angelica; Pereda-Suberbiola, Xabier (2023-06-03). "New contributions to the skull anatomy of spinosaurid theropods: Baryonychinae maxilla from the Early Cretaceous of Igea (La Rioja, Spain)". Historical Biology. 35 (6): 909–923. doi:10.1080/08912963.2022.2069019. ISSN 0891-2963.
12. Medeiros, Manuel Alfredo (2006). "Large theropod teeth from the Eocenomanian of northeastern Brazil and the occurrence of Spinosauridae". Revista Brasileira de Paleontologia. 9 (3): 333–338. doi:10.4072/rbp.2006.3.08.
13. Letizio LA, Bertini RJ, Medeiros MA (2022-07-16). "New evidence of putative Unenlagiinae (Deinonychosauria, Theropoda) in the São Luís-Grajaú Basin, Albian–Cenomanian, State of Maranhão, Brazil". Revista Brasileira de Paleontologia. 25 (2): 157–164. doi:10.4072/rbp.2022.2.05.
14. Kellner, A.W.A.; Pinheiro, A.E.P.; Azevedo, S.A.K.; Henriques, D.D.R.; de Carvalho, L.B.; Oliveira, G.R. (2009). "A new crocodyliform from the Alcântara Formation (Cenomanian), Cajual Island, Brazil". Zootaxa. 2030: 49–58. doi:10.11646/zootaxa.2030.1.4. S2CID 88042701.
15. Hsiou, A. S.; Albino, A. M.; Medeiros, M. A.; Santos, R. A. B. (2013). "The oldest Brazilian snakes from the early Late Cretaceous (Cenomanian)". Acta Palaeontologica Polonica. 59 (3): 635–642. doi:10.4202/app.2012.0091. hdl:11336/99860.
16. Neves, Gabrielle S.; Medeiros, Manuel Alfredo; Dutheil, Didier B.; Brito, Paulo M. (26 July 2024). "First record of Aegyptobatus (Hybodontiformes: Distobatidae) in the Cretaceous Alcântara formation (?Albian-Cenomanian) of Maranhão, Northeastern Brazil". Historical Biology: 1–7. doi:10.1080/08912963.2024.2379031.
17. Pereira, A.A.; Medeiros, M.A. (2008). "A new sclerorhynchiform (Elasmobranchii) from the middle Cretaceous of Brazil". Revista Brasileira de Paleontologia. 11 (3): 207–212. doi:10.4072/rbp.2008.3.07.
18. Toledo, C.E.; Sousa, E.P.; Medeiros, M.A.; Bertini, R.J. (2011). "A new genus of dipnoiformes from the Cretaceous of Brazil". Anais da Academia Brasileira de Ciências. 83 (4): 1181–1192. doi:10.1590/s0001-37652011000400006. hdl:11449/25070. PMID 22146953.
19. Eliane Pinheiro De Sousa; Manuel Alfredo Medeiros; Carlos Eduardo Vieira Toledo; Reinaldo J. Bertini; Agostinha Araújo Pereira; Rafael Matos Lindoso (2015). "A new species of Equinoxiodus (Dipnoi: ?Neoceratodontidae) from the Late Cretaceous of Brazil". Zootaxa. 3905 (3): 397–406. doi:10.11646/zootaxa.3905.3.5. PMID 25661218.
20. Medeiros, M.A., Carvalho, M.S.S., Silva, M.A.M., Pereira, A.A., Araujo, M.N., Ferreira, N.N., Vilas Bôas, I., 2011. O senhor dos rios: Mawsonia gigas (Mawsoniidae) do Cenomaniano do Maranhão, Brasil. In: Carvalho, I.S., Srivastava, N.K., Strohschoen, J.O., Lana, C.C. (Eds.), Paleontologia: Cenários de Vida, Vol. 4. Interciência, Rio de Janeiro, pp. 575-583.