Crato Formation

Crato Formation
Crato Formation
Stratigraphic range: Latest Aptian; ~115–113 Ma PreꞒ Ꞓ 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°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 Aptian age, about 113 million years ago. It thought to have been deposited in a semi-arid lacustrine wetland environment.^[1]

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,^[2] later redefined as the Romualdo Formation of the Santana Group.^[3]^[4] 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.^[5]

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.^[5] The Crato Formation is considered time equivalent with the Paracuru Formation.^[6]

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
Araripenymphes^[7]	A. seldoni	Nova Olinda Member	A Nymphid lacewing
Gracilepteryx	G. pulchra		An Eolepidopterigidae moth
Makarkinia^[8]	M. adamsi M. kerneri		A Kalligrammatid lacewing
Mickoleitia	M. longimanus		A Coxoplectopteran insect	Mickoleitia longimanus
Netoxena	N. nana		An Eolepidopterigidae moth
Principiala^[9]	P. incerta		An Ithonidae lacewing, type species of Principiala
Psamateia	P. calipsa		An Eolepidopterigidae moth
Rafaelia	R. maxima		Neuropterida incertae sedis
Undopterix	U. cariensis		An Eolepidopterigidae moth

Arachnids

Arachnids of the Crato Formation
Genus	Species	Presence	Description	Images
Protoischnurus	P. axelrodorum		Scorpion
Cratosolpuga	C. wunderlichi		Solifuge

Fish

Fish of the Crato Formation
Genus	Species	Presence	Description	Images	Notes
Araripelepidotes	Araripelepidotes temnurus				^[10]
Belonostomus	Belonostomus sp.				^[11]
Calamopleurus	Calamopleurus cylindricus				^[12]
Cladocyclus	Cladocyclus gardneri		An Ichthyodectidae fish		^[13]
Cratoamia	Cratoamia gondwanica				^[14]
Dastilbe	Dastilbe crandalli				^[15]
Lepidotes	Lepidotes wenzae				^[16]
Placidichthys	Placidichthys bidorsalis				^[17]
Santanichthys	Santanichthys diasii				^[18]

Amphibians

Amphibians of the Crato Formation
Genus	Species	Presence	Description	Images
Arariphrynus^[19]	Arariphrynus placidoi^[19]
Cratia^[19]	Cratia gracilis^[19]
Eurycephalella^[19]	Eurycephalella alcinae^[19]
Pipoidea^[19]	Possible indeterminate pipoid remains.^[19]

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

Dinosaurs

Dinosaurs of the Crato Formation
Genus	Species	Presence	Notes	Images
?Avialae	?Avialan species		Numerous isolated feathers
Cratoavis	C. cearensis		An enantiornithine
Kaririavis^[20]	K. mater		An ornithuromorph
?Spinosauroidea	?Spinosaur species		Isolated tooth
Ubirajara	U. jubatus		A compsognathid

Crocodylomorphs

Crocodylomorphs of the Crato Formation
Genus	Species	Presence	Description	Images
Susisuchus	Susisuchus anatoceps^[21]
Susisuchus	cf. Susisuchus sp.^[22]		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.	Holotype
Brasileodactylus	B. sp.
Lacusovagus	L. magnificens	Nova Olinda Member
Ludodactylus	L. sibbicki		An anhanguerid	Ludodactylus sp.
Tupandactylus	T. imperator T. navigans			Tupandactylus navigans
?Tupuxuara	?T. sp.			Tupuxuara 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.	^[23]

Other fossils

Araripenaeus timidus^[24]
†Cratoalloneura
- †Cratoalloneura acuminata
- †Cratoalloneura verdandia
†Cratoatractocerus
- †Cratoatractocerus grimaldii
†Cratoborellia
- †Cratoborellia gorbi
†Cratochrysa
- †Cratochrysa martinsnetoi
- †Cratochrysa sublapsa
- †Cratochrysa willmanni
†Cratocora
- †Cratocora crassa
†Cratocordulia
- †Cratocordulia borschukewitzi
†Cratocoris
- †Cratocoris shevchenkoae
†Cratocorydalopsis
- †Cratocorydalopsis brasiliensis
†Cratocossus
- †Cratocossus magnus
†Cratodactylus
- †Cratodactylus ferreirai
- †Cratodactylus kellneri
†Cratoelcana
- †Cratoelcana damianii
- †Cratoelcana zessini
†Cratoenigma
- †Cratoenigma articulata
†Cratogomphus
- †Cratogomphus erraticus
†Cratogryllus
- †Cratogryllus cigueli
- †Cratogryllus guimaraesae
- †Cratogryllus pentagonalis
†Cratohagenius
- †Cratohagenius erichweberi
†Cratohaglopsis
- †Cratohaglopsis santanaensis
†Cratohexagenites
- †Cratohexagenites longicercus
- †Cratohexagenites minor
†Cratokalotermes
- †Cratokalotermes santanensis
†Cratolindenia
- †Cratolindenia knuepfae
†Cratolocustopsis
- †Cratolocustopsis araripensis
- †Cratolocustopsis contumax’ – type locality for species
- †Cratolocustopsis cretacea
†Cratomacer
- †Cratomacer ephippiger
- †Cratomacer immersus
†Cratomastotermes
- †Cratomastotermes wolfschwenningeri
†Cratomyia
- †Cratomyia cretacica
- †Cratomyia macrorrhyncha
†Cratonemonyx
- †Cratonemonyx martinsnetoi
†Cratonemopteryx
- †Cratonemopteryx audax
- †Cratonemopteryx robusta
- †Cratonemopteryx speciosa
†Cratonepa
- †Cratonepa enigmatica
†Cratonerthra
- †Cratonerthra corinthiana
- †Cratonerthra estevezae
†Cratoneura
- †Cratoneura dividens
- †Cratoneura longissima
- †Cratoneura pulchella
†Cratonympha
- †Cratonympha microcelata
†Cratopelocoris
- †Cratopelocoris carpinteroi
†Cratopetalia
- †Cratopetalia whiteheadi
†Cratopetalura
- †Cratopetalura petruleviciusi
- †Cratopetalura petruleviciusi
†Cratopsychopsis
- †Cratopsychopsis maiseyi
†Cratopteryx
- †Cratopteryx nemopteroides
- †Cratopteryx robertosantosi
†Cratoraricrus
- †Cratoraricrus oberlii
†Cratoscalapha
- †Cratoscalapha electroneura
†Cratosirex
- †Cratosirex sennlaubi
†Cratosisyrops
- †Cratosisyrops gonzagai
†Cratosmylus
- †Cratosmylus magnificus
†Cratostenophlebia
- †Cratostenophlebia schwickerti
†Cratotabanus
- †Cratotabanus stonemyomorphus
†Cratotetraspinus
- †Cratotetraspinus fossorius
†Cratotipula
- †Cratotipula latialata
†Cratovitisma
- †Cratovitisma oldreadi
†Cratovoluptia
- †Cratovoluptia criptoneura
†Cratozeunerella
- †Cratozeunerella amedegnatoi
- †Cratozeunerella godoii
- †Cratozeunerella neotropica
- †Cratozeunerella nervosa
- †Cratozeunerella soaresi
- †Cratozeunerella titanella

References

^ Ribeiro, Alexandre Cunha; Ribeiro, Guilherme Cunha; Varejão, Filipe Giovanini; Battirola, Leandro Dênis; Pessoa, Edlley Max; Simões, Marcello Guimarães; Warren, Lucas Veríssimo; Riccomini, Claudio; Poyato-Ariza, Francisco José (May 2021). "Towards an actualistic view of the Crato Konservat-Lagerstätte paleoenvironment: A new hypothesis as an Early Cretaceous (Aptian) equatorial and semi-arid wetland". Earth-Science Reviews. 216: 103573. doi:10.1016/j.earscirev.2021.103573.
^ 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. 41 (4): e1988623. doi:10.1080/02724634.2021.1988623. S2CID 244059488.
^ Salisbury et al., 2003
^ Figueiredo & Kellner, 2009
^ Jorge de Lima et al., 2015, p.102
^ Pinheiro, 2014, p.4