Crato Formation
Crato Formation Stratigraphic range: Latest Aptian ~ | |
---|---|
Type | Geological formation |
Unit of | Santana Group |
Sub-units | Nova Olinda Member |
Underlies | Romualdo & Ipubi Formations |
Overlies | |
Lithology | |
Primary | Mudstone, limestone |
Other | Siltstone |
Location | |
Coordinates | 7°06′S 39°42′W / 7.1°S 39.7°WCoordinates: 7°06′S 39°42′W / 7.1°S 39.7°W |
Approximate paleocoordinates | 8°36′S 8°00′W / 8.6°S 8.0°W |
Region | Ceará, Pernambuco |
Country | Brazil |
Extent | Araripe Basin |
Type section | |
Named for | Crato, Ceará |
Extent of the Santana Group, to which the Crato Formation belongs, in blue |
The Crato Formation is a geologic formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätte (undisturbed fossil accumulation) for palaeontologists. The strata were laid down mostly during the early Aptian age, about 113 million years ago, in a shallow inland sea. At that time, the South Atlantic was opening up in a long narrow shallow sea.
The Crato Formation earns the designation of Lagerstätte due to an exceedingly well preserved and diverse fossil faunal assemblage. Some 25 species of fossil fishes are often found with stomach contents preserved, enabling paleontologists to study predator-prey relationships in this ecosystem. There are also fine examples of pterosaurs, reptiles and amphibians, invertebrates (particularly insects), and plants. Even dinosaurs are represented: a new maniraptor was described in 1996. The unusual taphonomy of the site resulted in limestone accretions that formed nodules around dead organisms, preserving even soft parts of their anatomy.
History[]
Fish fossils in the area were noted in 1823. When they were first methodically published, in 1993, the Crato Formation limestones provided a new site for pterosaurs, one that also preserved insects that fell into a brackish lagoon and semionotid fish preserved in phosphatized nodules. The fossils are usually compacted and preserved in layers of limestone. Fossil Odonata (dragonflies) and damselflies are especially rich in the Crato lagerstätte: currently 384 specimens have been recovered, 264 adults and 120 larvae. Hemiptera (true bugs) and Orthoptera (grasshoppers and crickets) are also abundant in number of species and in number of specimens. There are also plant remains.
Local mining activities for cement and construction damage the sites. Trade in illegally collected fossils has sprung up in the last decade, driven by the remarkable state of preservation and beauty of these fossils and amounting to a considerable local industry. An urgent preservation program is being called for by paleontologists.
In addition, the weathering of Crato and Santana Formation rocks has contributed soil conditions unlike elsewhere in the region. The Araripe manakin (Antilophia bokermanni) is a very rare bird that was discovered only in the late 20th century; it is not known from anywhere outside the characteristic forest that grows on the Chapada do Araripe soils formed ultimately from Crato and Santana Formation rocks.
Definition[]
The Crato Formation has often historically been considered the lowest member of the Santana Formation (or, alternatively, the Araripina Formation) of the Araripe Group,[1] later redefined as the Romualdo Formation of the Santana Group.[2][3] The Crato Member is the product of a single phase, where complicated sequence of sediment strata reflect changeable conditions in the opening sea. The age of this strata has been controversial, though most workers have agreed that it lies on or near the Aptian-Albian boundary, about 112 million years ago.[4]
The extent of the Crato unit and its relationship to the Romualdo Formation had long been ill-defined. It was not until a 2007 volume on the unit by Martill, Bechly and Loveridge that the Crato Formation was given a formal type locality, and was formally made a distinct formation separate from the Santana, which is about 10 Ma younger.[4] The Crato Formation is considered time equivalent with the .[5]
Fossil content[]
Insects[]
(Note: Many more insects have been described than are present in the table below)
Insects of the Crato Formation | ||||
---|---|---|---|---|
Genus | Species | Presence | Description | Images |
A. seldoni |
Nova Olinda Member |
A Nymphid lacewing |
||
G. pulchra |
An Eolepidopterigidae moth |
|||
M. adamsi |
A Kalligrammatid lacewing |
|||
Mickoleitia |
M. longimanus |
A Coxoplectopteran insect |
| |
N. nana |
An Eolepidopterigidae moth |
|||
P. incerta |
An Ithonidae lacewing, type species of Principiala |
|||
P. calipsa |
An Eolepidopterigidae moth |
|||
R. maxima |
||||
U. cariensis |
An Eolepidopterigidae moth |
Arachnids[]
Arachnids of the Crato Formation | ||||
---|---|---|---|---|
Genus | Species | Presence | Description | Images |
P. axelrodorum | Scorpion | |||
Cratosolpuga | C. wunderlichi | Solifuge |
Fish[]
Fish of the Crato Formation | |||||
---|---|---|---|---|---|
Genus | Species | Presence | Description | Images | Notes |
Araripelepidotes | Araripelepidotes temnurus | ||||
Belonostomus | Belonostomus sp. | ||||
Calamopleurus | Calamopleurus cylindricus | ||||
Cladocyclus | Cladocyclus gardneri | An Ichthyodectidae fish | |||
Cratoamia gondwanica | |||||
Dastilbe | Dastilbe crandalli | ||||
Lepidotes | Lepidotes wenzae | ||||
Placidichthys bidorsalis | |||||
Santanichthys | Santanichthys diasii |
Amphibians[]
Amphibians of the Crato Formation | ||||
---|---|---|---|---|
Genus | Species | Presence | Description | Images |
Arariphrynus placidoi[18] |
||||
Cratia gracilis[18] |
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Eurycephalella alcinae[18] |
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Possible indeterminate pipoid remains.[18] |
Squamata[]
Squamatans of the Crato Formation | ||||
---|---|---|---|---|
Genus | Species | Presence | Description | Images |
C. alamoi |
A non-iguana lizard |
|||
T. amplectus |
A stem group snake with limbs |
Dinosaurs[]
Dinosaurs of the Crato Formation | ||||
---|---|---|---|---|
Genus | Species | Presence | Notes | Images |
?Avialan species |
Numerous isolated feathers |
|||
C. cearensis |
An enantiornithine |
|||
K. mater |
An ornithuromorph |
|||
?Spinosauroidea |
?Spinosaur species |
Isolated tooth |
||
U. jubatus |
A compsognathid |
Crocodylomorphs[]
Crocodylomorphs of the Crato Formation | ||||
---|---|---|---|---|
Genus | Species | Presence | Description | Images |
Susisuchus anatoceps[20] |
||||
cf. Susisuchus sp.[21] |
Undescribed species |
Pterosaurs[]
Pterosaurs of the Crato Formation | ||||
---|---|---|---|---|
Genus | Species | Presence | Description | Images |
A. conandoylei |
||||
A. cearensis |
A basal member of the Tapejarinae. | |||
B. sp. |
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L. magnificens |
Nova Olinda Member |
|||
L. sibbicki |
An anhanguerid |
| ||
T. imperator |
| |||
?T. sp. |
Flora[]
Flora of the Crato Formation | |
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Species | Notes |
Araucaria cartellei, Brachyphyllum obesum, B. castilhoi, B. insigne, , Caytoniales sp., Ephedra sp., , Araucarites vulcanoi, , , , ,, , , Podozamites lanceolatus, , , , , , , , , , , |
Other fossils[]
- [23]
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See also[]
References[]
- ^ Scherer et al., 2013, p.28
- ^ Assine, 1992, p.291
- ^ Fabin et al., 2018, p.2050
- ^ a b Martill et al., 2007
- ^ Leite da Silva, 2003
- ^ Myskowiak, 2016
- ^ Bechly et al., 2016
- ^ Makarkin & Menon, 2007
- ^ Aparecida et al., 2015, p.25
- ^ Aparecida et al., 2015, p.35
- ^ Aparecida et al., 2015, p.29
- ^ Aparecida et al., 2015, p.36
- ^ Aparecida et al., 2015, p.31
- ^ Aparecida et al., 2015, p.51
- ^ Aparecida et al., 2015, p.26
- ^ Aparecida et al., 2015, p.33
- ^ Aparecida et al., 2015, p.47
- ^ a b c d e f g h Báez et al., 2009
- ^ de Souza Carvalho, I.; Agnolin, F. L.; Rozadilla, S.; Novas, F. E.; Ferreira Gomes Andrade, J. A.; Xavier-Neto, J. (2021). "A new ornithuromorph bird from the Lower Cretaceous of South America". Journal of Vertebrate Paleontology: e1988623. doi:10.1080/02724634.2021.1988623.
- ^ Salisbury et al., 2003
- ^ Figueiredo & Kellner, 2009
- ^ Jorge de Lima et al., 2015, p.102
- ^ Pinheiro, 2014, p.4
Bibliography[]
- ; ; , and . 2015. Guia de identificação de peixes fósseis das Formações Crato e Santana da Bacia do Araripe, 1–74. (CPRM).
- Análise estratigráfica da Bacia do Araripe, Nordeste do Brasil. Revista Brasileira de Geociências 22. 289–300. Accessed 2018-10-05. . 1992.
- Anurans from the Lower Cretaceous Crato Formation of northeastern Brazil: implications for the early divergence of neobatrachians. Cretaceous Research 30. 829–846. Accessed 2018-10-06. ; , and . 2009.
- A new gigantic lacewing species (Insecta: Neuroptera) from the Lower Cretaceous of Brazil confirms the occurrence of Kalligrammatidae in the Americas. Cretaceous Research 58. 135–140. Accessed 2018-10-06. , and . 2016.
- Stratigraphic Relations of the Ipubi Formation: Siliciclastic-Evaporitic Succession of the Araripe Basin. Anais da Academia Brasileira de Ciências 90. 2049–2071. Accessed 2018-10-05. ; ; ; ; ; ; , and . 2018.
- A new crocodylomorph specimen from the Araripe Basin (Crato Member, Santana Formation), northeastern Brazil. Paläontologische Zeitschrift 83. 323–331. Accessed 2018-10-06. , and . 2009.
- ; , and . 2012. Revisão da paleoflora das Formações Missão Velha, Crato e Romualdo, Bacia do Araripe, nordeste do Brasil. 22. 99–115.
- Formação Crato da Bacia do Araripe: um reservatório análogo ao Calcário Trairí (Formação Paracuru), Bacia do Ceará, 1–6. 2o Congresso Brasileiro de P&D em Petróleo & Gás. Accessed 2018-10-06. , and . 2003.
- First record of fossil 'rapismatid-like' Ithonidae (Insecta, Neuroptera) from the Lower Cretaceous Crato Formation of Brazil. Cretaceous Research 28. 743–753. Accessed 2018-10-06. , and . 2007.
- The Crato Fossil Beds of Brazil: Window into an Ancient World, 236. Cambridge University Press. Accessed 2018-10-06. ISBN 978-1-139-46776-6 ; , and . 2007.
- Shrimps from the Santana Group (Cretaceous: Albian): new species (Crustacea: Decapoda: Dendrobranchiata) and new record (Crustacea: Decapoda: Caridea). Anais da Academia Brasileira de Ciências _. 1–8. Accessed 2018-10-06. ; , and . 2014.
- A new crocodilian from the Lower Cretaceous Crato Formation of north-eastern Brazil. Palaeontographica, Abteilung A 270. 3–47. Accessed 2018-10-06. ; ; , and . 2003.
- Tectono-Stratigraphic evolution of the upper Jurassic-Neocomian rift succession, Araripe Basin, Northeast Brazil. _. 1–43. Accessed 2018-10-05. ; ; ; ; , and . 2013.
- ISBN 0-520-24209-2 . 2004. Dinosaur distribution (Early Cretaceous, South America) in: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 563–570. Berkeley: University of California Press.
Further reading[]
- Araripe Basin: A Major Geodiversity Hotspot in Brazil. Geoheritage _. 1–18. Accessed 2018-10-06. ; ; ; , and . 2017.
- Organic matter composition and distribution through the Aptian–Albian lacustrine sequences of the Araripe Basin, northeastern Brazil. 54. 21–40. Accessed 2018-10-05. ; ; , and . 2003.
- The first fossil horntail wasp (Hymenoptera: Siricidae) from Lower Cretaceous Crato Formation in Brazil. Palaeoentomology 003. 382–389. Accessed 2020-09-01. , and . 2020.
- The second genus of the ‘libelluloid’ family Araripephlebiidae (Odonata, Clavilabiata). Palaeoentomology 003. 240–244. Accessed 2020-08-01. , and . 2020.
- Crato Formation
- Geologic formations of Brazil
- Lower Cretaceous Series of South America
- Cretaceous Brazil
- Mudstone formations
- Limestone formations
- Deltaic deposits
- Lacustrine deposits
- Paleontology in Brazil
- Environment of Ceará
- Environment of Pernambuco
- Environment of Piauí
- Landforms of Ceará
- Landforms of Pernambuco
- Landforms of Piauí
- Northeast Region, Brazil