Crato Formation

Coordinates: 7°06′S 39°42′W / 7.1°S 39.7°W / -7.1; -39.7
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Crato Formation
Stratigraphic range: Latest Aptian
~115–113 Ma
TypeGeological formation
Unit ofSantana Group
Sub-unitsNova Olinda Member
UnderliesRomualdo & Ipubi Formations
OverliesBarbalha Formation
Lithology
PrimaryMudstone, limestone
OtherSiltstone
Location
Coordinates7°06′S 39°42′W / 7.1°S 39.7°W / -7.1; -39.7
Approximate paleocoordinates8°36′S 8°00′W / 8.6°S 8.0°W / -8.6; -8.0
Region Ceará,  Pernambuco
Country Brazil
ExtentAraripe Basin
Type section
Named forCrato, 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[edit]

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[edit]

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,[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[edit]

Insects[edit]

(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
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

Rafaeliana

R. maxima

Neuropterida incertae sedis

Undopterix

U. cariensis

An Eolepidopterigidae moth

Astraeoptera[10] A. vitrea An Astraeopteridae mayfly.
A. cretacica
A. oligovenata
Eosophobia[10] E. acuta An Astraeopteridae mayfly.

Arachnids[edit]

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

Fish[edit]

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 Cratoamia gondwanica
Dastilbe Dastilbe crandalli
Lepidotes Lepidotes wenzae
Placidichthys Placidichthys bidorsalis
Santanichthys Santanichthys diasii

Amphibians[edit]

Amphibians of the Crato Formation
Genus Species Presence Description Images

Arariphrynus[20]

Arariphrynus placidoi[20]

Cratia[20]

Cratia gracilis[20]

Eurycephalella[20]

Eurycephalella alcinae[20]

Pipoidea[20]

Possible indeterminate pipoid remains.[20]

Squamata[edit]

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[edit]

Dinosaurs of the Crato Formation
Genus Species Presence Notes Images

?Avialae

?Avialan species

Numerous isolated feathers

Cratoavis

C. cearensis

An enantiornithine

Kaririavis[21]

K. mater

An ornithuromorph

?Spinosauroidea

?Spinosaur species

Isolated tooth listed in a book appendix.[5] It has later been suggested that the lithostratigraphic provenance of this specimen might have been incorrect.[22]

"Ubirajara"

"U. jubatus"

An informally-named compsognathid known from a partial skeleton preserving integument

Sauropoda

Sauropoda footprints.[23]

Crocodylomorphs[edit]

Crocodylomorphs of the Crato Formation
Genus Species Presence Description Images

Susisuchus

Susisuchus anatoceps[24]

cf. Susisuchus sp.[25]

Undescribed species

Pterosaurs[edit]

Pterosaurs of the Crato Formation
Genus Species Presence Description Images

Arthurdactylus

A. conandoylei

Aymberedactylus

A. cearensis

A basal member of the Tapejarinae.
Holotype
Holotype

Brasileodactylus

B. sp.

Lacusovagus

L. magnificens

Nova Olinda Member

Ludodactylus

L. sibbicki

An anhanguerid

Ludodactylus sp.
Ludodactylus sp.

Tupandactylus

T. imperator
T. navigans

Tupandactylus navigans
Tupandactylus navigans

?Tupuxuara

?T. sp.

Tupuxuara sp.
Tupuxuara sp.

Flora[edit]

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.

Other fossils[edit]

See also[edit]

References[edit]

  1. ^ Ribeiro et al., 2021
  2. ^ Scherer et al., 2013, p. 28. Retrieved 2018-10-05.
  3. ^ Assine, 1992, p. 291. Retrieved 2018-10-05.
  4. ^ Fabin et al., 2018, p. 2050. Retrieved 2018-10-05.
  5. ^ a b c Martill et al., 2007. Retrieved 2018-10-06.
  6. ^ Leite da Silva, 2003. Retrieved 2018-10-06.
  7. ^ Myskowiak, 2016
  8. ^ Bechly et al., 2016. Retrieved 2018-10-06.
  9. ^ Makarkin & Menon, 2007. Retrieved 2018-10-06.
  10. ^ a b Storari, Arianny P.; Staniczek, Arnold H.; Godunko, Roman J. (2023-07-20). "A new Gondwanan mayfly family from the Lower Cretaceous Crato Formation, Brazil (Ephemeroptera: Siphlonuroidea: Astraeopteridae fam. nov.)". Scientific Reports. 13 (1): 11735. doi:10.1038/s41598-023-36778-x. ISSN 2045-2322. PMC 10359310. PMID 37474555.
  11. ^ Aparecida et al., 2015, p. 25
  12. ^ Aparecida et al., 2015, p. 35
  13. ^ Aparecida et al., 2015, p. 29
  14. ^ Aparecida et al., 2015, p. 36
  15. ^ Aparecida et al., 2015, p. 31
  16. ^ Aparecida et al., 2015, p. 51
  17. ^ Aparecida et al., 2015, p. 26
  18. ^ Aparecida et al., 2015, p. 33
  19. ^ Aparecida et al., 2015, p. 47
  20. ^ a b c d e f g h Báez et al., 2009. Retrieved 2018-10-06.
  21. ^ de Souza Carvalho et al., 2021
  22. ^ Caetano, João Marcus Vale; Delcourt, Rafael & Ponciano, Luiza Corral Martins de Oliveira (March 2023). "A taxon with no name: Ubirajara jubatus (Saurischia: Compsognathidae) is an unavailable name and has no nomenclatural relevance". Zootaxa. 5254 (3): 443–446. doi:10.11646/zootaxa.5254.3.10. PMID 37044710.
  23. ^ Ismar de Souza, Carvalho Vale; Leonardi, Giuseppe; Rios-Netto, Aristoteles de Moraes; Borghi, Leonardo; Freitas, Alexandre de Paula; Andrade, José Artur & Freitas, Francisco Idalécio (2021). "Dinosaur trampling from the Aptian of Araripe Basin, NE Brazil, as tools for paleoenvironmental interpretation". Cretaceous Research. 117: 104626. Bibcode:2021CrRes.11704626C. doi:10.1016/j.cretres.2020.104626.
  24. ^ Salisbury et al., 2003. Retrieved 2018-10-06.
  25. ^ Figueiredo & Kellner, 2009. Retrieved 2018-10-06.
  26. ^ Jorge de Lima et al., 2015, p.102
  27. ^ Pinheiro, 2014, p. 4. Retrieved 2018-10-06.

Bibliography[edit]

Further reading[edit]