Crato Formation

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.Ribeiro et al., 2021

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,Scherer et al., 2013, p. 28. Retrieved 2018-10-05. later redefined as the Romualdo Formation of the Santana Group.Assine, 1992, p. 291. Retrieved 2018-10-05.Fabin et al., 2018, p. 2050. Retrieved 2018-10-05. 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.Martill et al., 2007. Retrieved 2018-10-06.

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. The Crato Formation is considered time equivalent with the Paracuru Formation.Leite da Silva, 2003. Retrieved 2018-10-06.

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 ImagesAraripenymphesMyskowiak, 2016A. seldoniNova Olinda MemberA Cratosmylidae lacewingAestuacridaA. stereofemorisNova Olinda MemberA Locustopsid GrasshopperA. mikronaulionNova Olinda MemberA Locustopsid GrasshopperCratomastaxC. mariellaaeNova Olinda MemberA Eumastacoid GrasshopperGracilepteryxG. pulchraAn Eolepidopterigidae mothMakarkiniaBechly et al., 2016. Retrieved 2018-10-06.M. adamsi M. kerneriA Kalligrammatid lacewingMickoleitiaM. longimanusA Coxoplectopteran insectNetoxenaN. nanaAn Eolepidopterigidae mothPrincipialaMakarkin & Menon, 2007. Retrieved 2018-10-06.P. incertaAn Ithonidae lacewing, type species of PrincipialaPsamateiaP. calipsaAn Eolepidopterigidae moth RafaelianaR. maxima Neuropterida incertae sedisUndopterixU. cariensisAn Eolepidopterigidae mothAstraeopteraA. vitreaAn Astraeopteridae mayfly.A. cretacicaA. oligovenataEosophobiaE. acutaAn Astraeopteridae mayfly.VulcanidrisV. cratensisA hell ant

Arachnids Arachnids of the Crato Formation Genus Species Presence Description Images Mesoproctus M. rayoli Whip Scorpion Protoischnurus 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 Cratoamia gondwanica Dastilbe Dastilbe crandalli Lepidotes Lepidotes wenzae Placidichthys Placidichthys bidorsalis Santanichthys Santanichthys diasii

Amphibians Amphibians of the Crato Formation Genus Species Presence Description Images ArariphrynusBáez et al., 2009. Retrieved 2018-10-06.Arariphrynus placidoi CratiaCratia gracilis CratopipaCratopipa novaolindensis EurycephalellaEurycephalella alcinae KururubatrachusKururubatrachus gondwanicus PipoideaPossible indeterminate pipoid remains.

Squamata Squamates of the Crato Formation Genus Species Presence Description ImagesCalangubanC. alamoi A non-iguana lizardTetrapodophisT. amplectusA stem group snake with limbs

Dinosaurs Dinosaurs of the Crato Formation Genus Species Presence Notes Images ?Avialae?Avialan species Numerous isolated feathers CratoavisC. cearensis An enantiornithine Kaririavisde Souza Carvalho et al., 2021K. mater An ornithuromorph ?Spinosauroidea?Spinosaur species Isolated tooth listed in a book appendix. It has later been suggested that the lithostratigraphic provenance of this specimen might have been incorrect. "Ubirajara""U. jubatus"An informally-named compsognathid known from a partial skeleton preserving integument SauropodaSauropoda footprints.

Crocodylomorphs Crocodylomorphs of the Crato Formation Genus Species Presence Description ImagesSusisuchus Susisuchus anatocepsSalisbury et al., 2003. Retrieved 2018-10-06. cf. Susisuchus sp.Figueiredo & Kellner, 2009. Retrieved 2018-10-06. Undescribed species

Pterosaurs Pterosaurs of the Crato Formation Genus Species Presence Description Images ArthurdactylusA. conandoylei AymberedactylusA. cearensis Nova Olinda Member A basal member of the Tapejarinae. BrasileodactylusB. sp.Likely represents a specimen of Ludodactylus LacusovagusL. magnificens Nova Olinda Member LudodactylusL. sibbicki An anhanguerid TupandactylusT. imperator T. navigans ?Tupuxuara?T. sp. Chaoyangopteridae indet. IndeterminateNova Olinda Member UFC 721, a series of four articulated cervical vertebrae; may be referrable to LacusovagusTapejaridae indet.IndeterminateAzhdarchidae indet.IndeterminateNova Olinda MemberSMNK 2342 PAL, a partially articulated, distal portion of a left wing; may be referrable to Lacusovagus

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.

Fungi Fungi of the Crato Formation Genus Species Presence Description ImagesGondwanagaricites Gondwanagaricites magnificus EdaphagaricitesEdaphagaricites conicus

Other fossils

Araripenaeus timidusPinheiro, 2014, p. 4. Retrieved 2018-10-06. †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

See also

Araripe Basin Botucatu Formation Elrhaz Formation Itapecuru Formation Quiricó Formation

References

Bibliography

Further reading