Alcântara Formation
Brazilian geological formation
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The Alcântara Formation is a geological formation in northeastern Brazil whose strata date back to the Cenomanian of the Late Cretaceous.[1]
Unit ofItapecuru Group
UnderliesCujupe Formation
OverliesUndifferentiated unit
| 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 |
| Approximate paleocoordinates | 9.4°S 19.3°W |
| 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
|
Notes Uncertain or tentative taxa are in small text; |
Dinosaurs
Ornithischians
| Ornithischians of the Alcântara Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image |
| Ornithopoda indet. | Indeterminate | Laje do Coringa, Cajual Island | Footprints [2] | Footprints interpreted as coming from both small and large ornithopods. Larger footprints have been tentatively assigned to hadrosaurs. | ||
Sauropods
| Sauropods of the Alcântara Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Itapeuasaurus[3] | I. cajapioensis | Itapeua beach | A rebbachisaurid sauropod |  | ||
| cf. Limaysaurus[4] | L. tessonei | Laje do Coringa, Cajual Island | Vertebrae | A rebbachisaurid sauropod | ||
| cf. Malawisaurus?[5][6] | M. sp. | Laje do Coringa, Cajual Island | Tooth | A tooth similar to Malawisaurus |  | |
| Sauropoda indet.[6] | Indeterminate | Laje do Coringa, Cajual Island | Teeth | May belong to a titanosaurian or a diplodocoid rebbachisaurid | ||
| Titanosauria indet.[6] | 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.[7] | Indeterminate | Laje do Coringa, Cajual Island | Two shed tooth crowns | A abelisaurid theropod | ||
| Carcharodontosauridae indet.[8] | Indeterminate | Laje do Coringa, Cajual Island | Teeth | A carcharodontosaurid theropod | ||
| Dromaeosauridae indet.[6] | Indeterminate | Laje do Coringa, Cajual Island | Teeth | Possible member of Velociraptorinae | ||
| Noasauridae indet.[9] | Indeterminate | Laje do Coringa, Cajual Island | Nine teeth | A noasaurid theropod; closely related to Masiakasaurus. | ||
| Oxalaia[10] | 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.[11] However, this has been disputed.[12] |  | |
|
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.[13] |
|||
| Spinosauridae indet.[14] | Indeterminate | Laje do Coringa, Cajual Island | Teeth | A spinosaurid theropod different from Oxalaia. | ||
| Unenlagiinae[15] | 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.[6] | 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[6] | C. itapecuruense | Laje do Coringa, Cajual Island | Teeth | A notosuchian | ||
| Coringasuchus[16] | 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.[6] | Indeterminate | Laje do Coringa, Cajual Island | Incomplete carapace | |||
Squamates
Mosasaurs
| Mosasaurs of the Alcântara Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Carinodens[6] | C. fraasi | Laje do Coringa, Cajual Island | Dental | A globidensin mosasaurine |  | |
Fish
| Fishes of the Alcântara Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Adrianaichthys[18] | A. pankowski | Laje do Coringa, Cajual Island | Scales | A lepisosteiform fish | ||
| Aegyptobatus[19] | A. kuehnei | Laje de Coringa, Cajual Island | A distobatid hybodont | |||
| Arganodus[6] | A. tiguidiensis | Laje do Coringa, Cajual Island | Dental plates | A ceratodontid lungfish |  | |
| Atlanticopristis[20] | A. equatorialis | Falésia do Sismito and Laje do Coringa, Cajual Island | Fourteen denticle specimens (two complete) | A sclerorhynchoid |  | |
| Bartschichthys[6] | B. sp. | Laje do Coringa, Cajual Island | Spines | A cladistian | ||
| Ceratodus[6] | C. brasiliensis | Laje do Coringa, Cajual Island | Dental plates | A ceratodontid lungfish |  | |
| C. humei | ||||||
| Equinoxiodus[6] | E. alcantarensis[21] | Laje do Coringa, Cajual Island | One complete and eight incomplete tooth plates | A neoceatodontid lungfish | ||
| E. schuitzei[22] | ||||||
| Lepidotes[6] | L. sp. | Laje do Coringa, Cajual Island | Mineralized scales | A lepidotid fish. | ||
| Lepisosteidae Indet.[23] | Indeterminate | Laje do Coringa, Cajual Island | Scales | |||
| Mawsonia[24] | M. gigas | Laje do Coringa, Cajual Island | Palato-quadrate and post-parietal cranial material | A mawsoniid coelacanth. |  | |
| Myliobatis[6] | M. dixoni | Laje do Coringa, Cajual Island | A myliobatid eagle ray | |||
| Obaichthys[6] | O. africanus | Laje do Coringa, Cajual Island | Scales | A obaichthyid lepisosteiform | ||
| Onchopristis | cf. O. numida[25] | Laje do Coringa, Cajual Island | Rostral teeth | A sclerorhynchoid |  | |
| Pycnodontiformes indet.[6] | Indeterminate | Laje do Coringa, Cajual Island | Dental plate and teeth | |||
| Stephanodus[6] | S. sp. | Laje do Coringa, Cajual Island | Pharyngeal teeth | A pycnodontid fish | ||
| Tribodus[6] | T. limae | Laje do Coringa, Cajual Island | Dorsal spines | A hybodont shark | ||