Crato Formation

Crato Formation
Stratigraphic range: Latest Aptian
~115–113 Ma

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Crato Formation; Stratigraphic range: Latest Aptian; ~115–113 Ma PreЄ Є O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Santana Group
Sub-units	Nova Olinda Member
Underlies	Romualdo & Ipubi Formations
Overlies	Barbalha Formation
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

Schematic development of the depositional environments of the Santana Group

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

Lake level cyclicity in the Santana Group

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 Paracuru Formation.^[5]

Fossil content

Insects

Insects of the Crato Formation
Genus	Species	Presence	Description	Images
Araripenymphes^[6]	A. seldoni	Nova Olinda Member	A Nymphid lacewing
Gracilepteryx	G. pulchra		A Eolepidopterigidae moth
Makarkinia^[7]	M. adamsi M. kerneri		A Kalligrammatid lacewing
Mickoleitia	M. longimanus		A Coxoplectopteran insect
Netoxena	N. nana		A Eolepidopterigidae moth
Principiala^[8]	P. incerta		An Ithonidae lacewing, type species of Principiala
Psamateia	P. calipsa		A Eolepidopterigidae moth
Rafaelia	R. maxima		Neuropterida incertae sedis
Undopterix	U. cariensis		An Eolepidopterigidae moth

Arthropods

Arthropods of the Crato Formation
Genus	Species	Presence	Description	Images
Protoischnurus	P. axelrodorum		Scorpion

Fish

Fish of the Crato Formation
Genus	Species	Presence	Description	Images	Notes
Araripelepidotes	Araripelepidotes temnurus				^[9]
Belonostomus	Belonostomus sp.				^[10]
Calamopleurus	Calamopleurus cylindricus				^[11]
Cladocyclus	Cladocyclus gardneri		An Ichthyodectidae fish		^[12]
Cratoamia	Cratoamia gondwanica				^[13]
Dastilbe	Dastilbe crandalli				^[14]
Lepidotes	Lepidotes wenzae				^[15]
Placidichthys	Placidichthys bidorsalis				^[16]
Santanichthys	Santanichthys diasii				^[17]

Amphibians

Amphibians of the Crato Formation
Genus	Species	Presence	Description	Images
Arariphrynus^[18]	Arariphrynus placidoi^[18]
Cratia^[18]	Cratia gracilis^[18]
Eurycephalella^[18]	Eurycephalella alcinae^[18]
Pipoidea^[18]	Possible indeterminate pipoid remains.^[18]

Squamata

Squamatans of the Crato Formation
Genus	Species	Presence	Description	Images
Calanguban	C. alamoi		A non-iguana lizard
Tetrapodophis	T. amplectus		A stem group snake with limbs

Dinosauria

Dinosaurs and birds of the Crato Formation
Genus	Species	Presence	Notes	Images
?Avialae	?Avialan species		Numerous isolated feathers
Cratoavis	C. cearensis		Enantiornithine	Reconstruction of Cratoavis and Mirischia
?Spinosauroidea	?Spinosaur species		Isolated tooth

Crurotarsans

Crocodylomorphs of the Crato Formation
Genus	Species	Presence	Description	Images
Susisuchus	Susisuchus anatoceps^[19]
Susisuchus	cf. Susisuchus sp.^[20]		Undescribed species

Pterosaurs

Pterosaurs of the Crato Formation
Genus	Species	Presence	Description	Images
Arthurdactylus	A. conandoylei
Aymberedactylus	A. cearensis		A basal member of the Tapejarinae.
Brasileodactylus	B. sp.
Lacusovagus	L. magnificens	Nova Olinda Member
Ludodactylus	L. sibbicki		An ornithocheirid
Tupandactylus	T. imperator T. navigans
?Tupuxuara	?T. sp.

Flora

Flora of the Crato Formation
Species	Notes
Araucaria cartellei, Brachyphyllum obesum, B. castilhoi, B. insigne, Iara iguassu, Caytoniales sp., Ephedra sp., Araripia florifera, Araucarites vulcanoi, Cariria orbiculiconiformis, Cearania heterophylla, Cratonia cotyledon, Endressinia brasiliana,Klitzchophyllites flabellatus, Novaolindia dubia, Pluricarpellatia peltata, Podozamites lanceolatus, Protananas lucenae, Ruffordia goeppertii, Tomaxellia biforme, Welwitschiaprisca austroamericana, Welwitschiophyllum brasiliense, Welwitschiostrobus murili, Araucariostrobus sp., Frenelopsis sp., Isoetites sp., Lindleycladus sp., Schizoneura sp.	^[21]

Other fossils

Araripenaeus timidus^[22]
† Cratoalloneura – type locality for genus
- † Cratoalloneura acuminata – type locality for species
- † Cratoalloneura verdandia – type locality for species
† Cratoatractocerus – type locality for genus
- † Cratoatractocerus grimaldii – type locality for species
† Cratoborellia – type locality for genus
- † Cratoborellia gorbi – type locality for species
† Cratochrysa – type locality for genus
- † Cratochrysa martinsnetoi – type locality for species
- † Cratochrysa sublapsa – type locality for species
- † Cratochrysa willmanni – type locality for species
† Cratocora – type locality for genus
- † Cratocora crassa – type locality for species
† Cratocordulia – type locality for genus
- † Cratocordulia borschukewitzi – type locality for species
† Cratocoris – type locality for genus
- † Cratocoris shevchenkoae – type locality for species
† Cratocorydalopsis – type locality for genus
- † Cratocorydalopsis brasiliensis – type locality for species
† Cratocossus – type locality for genus
- † Cratocossus magnus – type locality for species
† Cratodactylus – type locality for genus
- † Cratodactylus ferreirai – type locality for species
- † Cratodactylus kellneri – type locality for species
† Cratoelcana – type locality for genus
- † Cratoelcana damianii – type locality for species
- † Cratoelcana zessini – type locality for species
† Cratoenigma – type locality for genus
- † Cratoenigma articulata – type locality for species
† Cratogomphus – type locality for genus
- † Cratogomphus erraticus – type locality for species
† Cratogryllus – type locality for genus
- † Cratogryllus cigueli – type locality for species
- † Cratogryllus guimaraesae – type locality for species
- † Cratogryllus pentagonalis – type locality for species
† Cratohagenius – type locality for genus
- † Cratohagenius erichweberi – type locality for species
† Cratohaglopsis – type locality for genus
- † Cratohaglopsis santanaensis – type locality for species
† Cratohexagenites – type locality for genus
- † Cratohexagenites longicercus – type locality for species
- † Cratohexagenites minor – type locality for species
† Cratokalotermes – type locality for genus
- † Cratokalotermes santanensis – type locality for species
† Cratolindenia – type locality for genus
- † Cratolindenia knuepfae – type locality for species
† Cratolocustopsis
- † Cratolocustopsis araripensis – type locality for species
- † Cratolocustopsis contumax’ – type locality for species
- † Cratolocustopsis cretacea – type locality for species
† Cratomacer – type locality for genus
- † Cratomacer ephippiger – type locality for species
- † Cratomacer immersus – type locality for species
† Cratomastotermes – type locality for genus
- † Cratomastotermes wolfschwenningeri – type locality for species
† Cratomyia – type locality for genus
- † Cratomyia cretacica – type locality for species
- † Cratomyia macrorrhyncha – type locality for species
† Cratonemonyx – type locality for genus
- † Cratonemonyx martinsnetoi – type locality for species
† Cratonemopteryx – type locality for genus
- † Cratonemopteryx audax – type locality for species
- † Cratonemopteryx robusta – type locality for species
- † Cratonemopteryx speciosa – type locality for species
† Cratonepa – type locality for genus
- † Cratonepa enigmatica – type locality for species
† Cratonerthra – type locality for genus
- † Cratonerthra corinthiana – type locality for species
- † Cratonerthra estevezae – type locality for species
† Cratoneura – type locality for genus
- † Cratoneura dividens – type locality for species
- † Cratoneura longissima – type locality for species
- † Cratoneura pulchella – type locality for species
† Cratonympha – type locality for genus
- † Cratonympha microcelata – type locality for species
† Cratopelocoris – type locality for genus
- † Cratopelocoris carpinteroi – type locality for species
† Cratopetalia – type locality for genus
- † Cratopetalia whiteheadi – type locality for species
† Cratopetalura – type locality for genus
† Cratopetalura
- † Cratopetalura petruleviciusi – type locality for species
- † Cratopetalura petruleviciusi
† Cratopsychopsis – type locality for genus
- † Cratopsychopsis maiseyi – type locality for species
† Cratopteryx – type locality for genus
† Cratopteryx
- † Cratopteryx nemopteroides – type locality for species
- † Cratopteryx robertosantosi – type locality for species
† Cratoraricrus – type locality for genus
- † Cratoraricrus oberlii – type locality for species
† Cratoscalapha – type locality for genus
- † Cratoscalapha electroneura – type locality for species
† Cratosisyrops – type locality for genus
- † Cratosisyrops gonzagai – type locality for species
† Cratosmylus – type locality for genus
- † Cratosmylus magnificus – type locality for species
† Cratosolpuga
- † Cratosolpuga wunderlichi – type locality for species
† Cratostenophlebia – type locality for genus
- † Cratostenophlebia schwickerti – type locality for species
† Cratotabanus – type locality for genus
- † Cratotabanus stonemyomorphus – type locality for species
† Cratotetraspinus – type locality for genus
- † Cratotetraspinus fossorius – type locality for species
† Cratotipula – type locality for genus
- † Cratotipula latialata – type locality for species
† Cratovitisma – type locality for genus
- † Cratovitisma oldreadi – type locality for species
† Cratovoluptia – type locality for genus
- † Cratovoluptia criptoneura – type locality for species
† Cratozeunerella – type locality for genus
- † Cratozeunerella amedegnatoi – type locality for species
- † Cratozeunerella godoii – type locality for species
- † Cratozeunerella neotropica – type locality for species
- † Cratozeunerella nervosa – type locality for species
- † Cratozeunerella soaresi – type locality for species
- † Cratozeunerella titanella – type locality for species

References

↑ Scherer et al., 2013, p.28
↑ Assine, 1992, p.291
↑ Fabin et al., 2018, p.2050
1 2 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
1 2 3 4 5 6 7 8 Báez et al., 2009
↑ Salisbury et al., 2003
↑ Figueiredo & Kellner, 2009
↑ Jorge de Lima et al., 2015, p.102
↑ Pinheiro, 2014, p.4

Bibliography

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Assine, Mario L. 1992. Análise estratigráfica da Bacia do Araripe, Nordeste do Brasil. Revista Brasileira de Geociências 22. 289–300. Accessed 2018-10-05.
Báez, A.M.; G.J.B. Moura, and R.O. Gómez. 2009. 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.
Bechly, G., and V. N. Makarkin. 2016. 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.
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Makarkin, V.N., and F. Menon. 2007. 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.
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Pinheiro, Allysson P.; Antônio Á.F. Saraiva, and William Santana. 2014. 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.
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