The Açu Formation is an Early Cretaceous (Albian) geologic formation of the Potiguar Basin in Ceará, northeastern Brazil. The formation comprises coarse-grained sandstones deposited in a fluvio-deltaic environment. The Açu Formation, belonging to the Apodi Group, has provided fossils of an indeterminate rebbachisaurid.
| Açu Formation | |
|---|---|
| Stratigraphic range: Albian ~ | |
| Type | Geological formation |
| Unit of | Apodi Group |
| Underlies | Jandaíra Formation |
| Overlies | Alagamar Formation |
| Lithology | |
| Primary | Sandstone |
| Location | |
| Coordinates | 5°48′S 38°06′W / 5.8°S 38.1°W |
| Approximate paleocoordinates | 11°54′S 10°54′W / 11.9°S 10.9°W |
| Region | Ceará |
| Country |  Brazil |
| Extent | Potiguar Basin |
  Açu Formation (Brazil) | |
Description
editThe Açu Formation was deposited in a passive margin setting, overlying the Alagamar Formation and is overlain by the Jandaíra Formation. In the petroleum producing Potiguar Basin, the formation is a reservoir rock.[1]
Fossil content
editThe following fossils were reported from the formation:[2]
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Dinosaurs
editSauropods
edit| Sauropods of the Açu Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Rebbachisauridae indet.[3] | Indeterminate | |||||
| Tiamat[4][5] | T. valdecii | Caudal Vertebrae and Osteoderm | a titanosaurian sauropoda; closely related to Andesaurus delgadoi. |  | ||
Theropods
edit| Theropods of the Açu Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Abelisauridae Indet. | Indeterminate | |||||
| Carcharodontosauridae Indet. | Indeterminate | |||||
| Maniraptora Indet. | Indeterminate | |||||
| Megaraptora Indet. | Indeterminate | |||||
| Spinosauridae Indet. | Indeterminate | |||||
Turtles
edit| Turtles of the Açu Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Apodichelys | A. lucianoi | A pelomedusid turtle | ||||
Fish
edit| Fishes of the Koum Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
| Amiidae Indet. | Indeterminate | |||||
| Arganodus | A. cf. tinguidiensis | A ceratodontid lungfish | ||||
| Bawitius | B. cf. bartheli | A giant bichir | ||||
| Ceratodus | C. latissimus | A ceratodontid lungfish | ||||
| Lepisosteiformes Indet. | Indeterminate | |||||
| Mawsonia | M. cf. gigas | A mawsonnid coelacanth | ||||
| Pycnodontiformes indet. | Indeterminate | |||||
| Tharrhias | T. rochae | A gonorynchiform fish | ||||
| Tribodus | T. cf. limae | A hybodont shark | ||||
See also
editReferences
edit- ^ Maraschin et al., 2010, p.87
- ^ Açu Formation at Fossilworks.org
- ^ Gomes da Costa Pereira et al., 2020
- ^ Pereira, P.V.L.G.C.; Marinho, T.S.; Candeiro, C.R.A.; Bergqvist, L.P. (2018). "A new titanosaurian (Sauropoda, Dinosauria) osteoderm from the Cretaceous of Brazil and its significance". Ameghiniana. 55 (6): 644–650. doi:10.5710/AMGH.26.08.2018.3168.
- ^ Pereira, P. V. L. G. C.; Bandeira, K. L. N.; Vidal, L. S.; Ribeiro, T. B.; Candeiro, C. R. A.; Bergqvist, L. P. (2024). "A new sauropod species from north-western Brazil: biomechanics and the radiation of Titanosauria (Sauropoda: Somphospondyli)". Zoological Journal of the Linnean Society. doi:10.1093/zoolinnean/zlae054.
Bibliography
edit- Gomes da Costa Pereira, Paulo Victor; Ribeiro, Theo Baptista; Brusatte, Stephen Louis; Dos Anjos Candeiro, Carlos Roberto; da Silva Marinho, Thiago; Paglarelli Bergqvist, Lilian (2020), "Theropod (Dinosauria) diversity from the Potiguar basin (Early-late Cretaceous Albian – Cenomanian), Northeast Brazil" (PDF), Cretaceous Research, in press: Article 104517, doi:10.1016/j.cretres.2020.104517, hdl:20.500.11820/849a673d-9aa1-4b8e-be0c-f630af8a5d5e
- Maraschin, Anderson; Mizusaki, Ana Maria P.; Vasconcelos, P.M.; Hinrichs, Ruth (2010), "Depositional age definition of the Açu Formation (Potiguar Basin, northeastern Brazil) through 40Ar-39Ar dating of early-authigenic K-feldspar overgrowths", Pesquisas Em Geociencias, 37: 85–96, doi:10.22456/1807-9806.22649, retrieved 2020-06-18