View source for Romualdo Formation

{{Short description|Brazilian geologic formation}}
{{Use dmy dates|date=June 2019}}
{{Infobox rockunit
| name           = Romualdo Formation
| image          = Anhanguera santanae.jpg
| caption        = Fossils of ''[[Anhanguera (pterosaur)|Anhanguera]]'' (top) and ''[[Santanadactylus]]'' (bottom) from the Romualdo Formation
| type           = [[Geological formation]]
| age            = [[Albian|Early Albian]]<br />~{{fossil range|111|108}}
| period         = Aptian
| prilithology   = [[Mudstone]]
| otherlithology = [[Limestone]], [[shale]]
| namedfor       = 
| namedby        =
| region         = [[Pernambuco]], [[Piauí]] & [[Ceará]]
| country        = [[Brazil]]
| coordinates    = {{coord|7.2|S|39.3|W|display=inline,title}}
| paleocoordinates = {{coord|12.2|S|10.7|W|display=inline}}
| unitof         = [[Santana Group]]
| subunits       = 
| underlies      = [[Exu Formation|Exu]] & [[Arajara Formation]]s
| overlies       = [[Crato Formation|Crato]] & [[Ipubi Formation]]s
| thickness      = {{convert|2|-|10|m|ft|abbr=on}}
| extent         = [[Araripe Basin]]
| area           =
| map            = Araripe Basin map - formations and resources.jpg
| map_caption    = Extent of the Santana Group, to which the Romualdo Formation belongs, in blue
}}

The '''Romualdo Formation''' is a geologic [[Lagerstätte|Konservat-Lagerstätte]] in northeastern [[Brazil]]'s [[Araripe Basin]] where the states of [[Pernambuco]], [[Piauí]] and [[Ceará]] come together. The geological formation, previously designated as the Romualdo Member of the '''[[Santana Group|Santana Formation]]''', named after the village of [[Santana do Cariri]], lies at the base of the [[Chapada do Araripe|Araripe Plateau]]. It was discovered by [[Johann Baptist von Spix]] in 1819. The [[Stratum|strata]] were deposited during the [[Aptian]] stage of the [[Early Cretaceous]] in a [[lacustrine]] [[rift basin]] with shallow marine incursions of the [[Iapetus Ocean|proto-Atlantic]]. At that time, the South Atlantic was opening up in a long narrow shallow sea.

The Romualdo Formation earns the designation of Lagerstätte due to an exceedingly well preserved and diverse [[fossil]] faunal assemblage. Some 25 species of [[fossil fish]]es are often found with stomach contents preserved, enabling paleontologists to study [[Predation|predator–prey]] relationships in this ecosystem. There are also fine examples of [[pterosaur]]s, [[reptile]]s and [[invertebrate]]s, and [[crocodylomorphs]]. Even dinosaurs are represented ([[Spinosauridae]], [[Tyrannosauroidea]], [[Compsognathidae]]). The unusual [[taphonomy]] of the site resulted in [[limestone]] [[Accretion (geology)|accretions]] that formed nodules around dead organisms, preserving even soft parts of their anatomy. In preservation, the nodules are etched away with acid, and the fossils often prepared by the [[transfer technique]].<ref name=Maisey1991_pp99_103>Maisey et al., 1991, pp. 99–103</ref>

Local mining activities for cement and construction damage the sites. [[Black market|Trade in illegally]] collected fossils has sprung up from the decade of 1970, 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.<ref>{{Cite journal|last=Gibney|first=Elizabeth|date=2014-03-06|title=Brazil clamps down on illegal fossil trade|journal=Nature|language=en|volume=507|issue=7490|pages=20|doi=10.1038/507020a|pmid=24598620|issn=0028-0836|bibcode=2014Natur.507...20G|doi-access=free}}</ref>

In addition, the [[weathering]] of Romualdo 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 Romualdo Formation rocks.

== Geology and dating ==
[[File:Romualdo Formation - outcrop and interpretation.jpg|thumb|right|200px|Outcrop and interpretation of the Romualdo Formation]]
[[File:Ipubi and Romualdo Formations - outcrop.jpg|thumb|right|200px|Outcrop of the Romualdo and Ipubi Formations]]
{{main|Santana Group#Basin history}}
The [[Crato Formation]] was previously considered the lowest member of the then Santana Formation, but has been elevated to a formal formation. The Crato Formation is the product of a single phase, where complicated sequence of sediment [[stratum|strata]] reflect changeable conditions in the opening sea. The age of the Romualdo Formation, formerly known as the Romualdo Member of the Santana Formation, has been controversial, though most workers have agreed that it lies on or near the [[Aptian]]-[[Albian]] boundary, about 112 million years ago. Nevertheless, a [[Cenomanian]] age cannot be ruled out.<ref name=martilletal2007>Martill et al., 2007</ref><ref name="martill2007b">Martill, 2007</ref>

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 Romualdo Formation, which is about 10 Ma younger.<ref name=martilletal2007/>

== Fossil content ==

=== Archosaurs ===
Indeterminate remains of non-avian [[Theropoda|theropods]], [[Avialae|avialans]], [[ornithischia]]ns, and possibly [[Oviraptorosauria|oviraptorosaurs]] have been found in Ceara state, Brazil.<ref name="cretaceousdistribution" /> The oviraptorosaurian remains have been re-identified as [[megaraptora]]n fossils.<ref>{{Cite journal|last1=Aranciaga Rolando|first1=Alexis M.|last2=Brissón Egli|first2=Federico|last3=Sales|first3=Marcos A.F.|last4=Martinelli|first4=Agustín G.|last5=Canale|first5=Juan I.|last6=Ezcurra|first6=Martín D.|date=2018|title=A supposed Gondwanan oviraptorosaur from the Albian of Brazil represents the oldest South American megaraptoran|journal=Cretaceous Research|language=en|volume=84|pages=107–119|doi=10.1016/j.cretres.2017.10.019|bibcode=2018CrRes..84..107A |issn=0195-6671|hdl=11336/93821|hdl-access=free}}</ref>

==== Dinosaurs ====
{| class="wikitable" align="center"
|-
! colspan="5" align="center" | '''[[Dinosaur]]s'''
|-
! Genus !! Species !! Presence !! Notes !! Images
|-
| style="background:#E6E6E6;" | ''[[Angaturama]]''<ref name="cretaceousdistribution">Weishampel, 2004, pp. 563–570</ref>
| style="background:#E6E6E6;" | ''A. limai''
| style="background:#E6E6E6;" | Ceará
| style="background:#E6E6E6;" | [[Spinosauridae]]. Partial skull (rostralmost portion).<ref name="table-4-1-73">"Table 4.1," in Weishampel, et al. (2004). Page 73.</ref> Possible junior synonym of ''Irritator challengeri''.
| [[File:Angaturama limai skeleton.jpg|center|150px]]
|-
| ''[[Aratasaurus]]''<ref>{{Cite journal|author1=Juliana Manso Sayão |author2=Antônio Álamo Feitosa Saraiva |author3=Arthur Souza Brum |author4=Renan Alfredo Machado Bantim |author5=Rafael Cesar Lima Pedroso de Andrade |author6=Xin Cheng |author7=Flaviana Jorge de Lima |author8=Helder de Paula Silva |author9=Alexander W. A. Kellner |year=2020 |title=The first theropod dinosaur (Coelurosauria, Theropoda) from the base of the Romualdo Formation (Albian), Araripe Basin, Northeast Brazil |journal=Scientific Reports |volume=10 |issue=1 |pages=Article number 10892 |doi=10.1038/s41598-020-67822-9 |pmid=32651406 |pmc=7351750 |doi-access=free |bibcode=2020NatSR..1010892S }}</ref>
| ''A. museunacionali''
| Ceará 
| A [[coelurosaur]]. Partial right hindlimb.
| [[File:Aratasaurus museunacionali.jpg|center|150px]]
|-
| ''[[Irritator]]''<ref name="cretaceousdistribution" /><ref>{{Cite journal|last1=Martill|first1=D. M.|last2=Cruickshank|first2=A. R. I.|last3=Frey|first3=E.|last4=Small|first4=P. G.|last5=Clarke|first5=M.|date=1996-02-01|title=A new crested maniraptoran dinosaur from the Santana Formation (Lower Cretaceous) of Brazil|journal=Journal of the Geological Society|language=en|volume=153|issue=1|pages=5–8|doi=10.1144/gsjgs.153.1.0005|issn=0016-7649|bibcode=1996JGSoc.153....5M|s2cid=131339386|url=http://doc.rero.ch/record/14940/files/PAL_E2087.pdf }}</ref>
| ''I. challengeri''
| Ceará
| [[Spinosauridae]]. Partial skull (posterior half); one of the most complete spinosaurid skulls known.
| [[File:Irritator Life Reconstruction.jpg|center|150px]]
|-
| ''[[Mirischia]]''<ref name="cretaceousdistribution" />
| ''M. asymmetrica''
| Pernambuco
| [[Compsognathidae]]. Pelvis and partial left hindlimb.
| [[File:Mirischia asymmetrica by Ademar Pereira.JPG|center|150px]]
|-
| ''[[Santanaraptor]]''<ref name="cretaceousdistribution" />
| ''S. placidus''
| Ceará
| A possible [[tyrannosauroidea|tyrannosauroid]]. Some caudal vertebrae, partial pelvis, most of both hindlimbs.<ref name="table-5-1-114">"Table 5.1," in Weishampel, et al. (2004). Page 114.</ref>
| [[File:Santanaraptor.jpg|center|150px]]
|-
|}

==== Crocodylomorphs ====
{| class="wikitable" align="center"
|-
! colspan="5" align="center" | '''[[Crocodylomorph]]s'''
|-
! Genus !! Species !! Presence !! Notes !! Images
|-
| ''[[Araripesuchus]]''
| ''A. gomesii''
| Romualdo Formation
| Type specimen 423-R is a single skull articulating with part of a lower jaw. A more complete specimen, AMNH 24450, is at the [[American Museum of Natural History]].
| [[File:Araripesuchus wegeneri.jpg|center|150px]]
|-
|''[[Caririsuchus]]''
|''C. camposi''
|Romualdo Formation
|A [[Peirosauridae|peirosaurid]] crocodyliform.
|
|-
|}

=== Pterosaurs ===
{| class="wikitable" align="center"
|-
! colspan="4" align="center" | '''[[Pterosaur]]s'''
|-
! Genus !! Species !! Presence !! Images
|-
| ''[[Anhanguera (pterosaur)|Anhanguera]]''
|
* ''A. blittersdorffi''

*''A. santanae''
* ''A. araripensis''
* ''A. robustus''
* ''A. piscator''
* ''A. spielbergi''
| 
| [[File:Anhanguera blittersdorffi Life Restoration by Matt Martyniuk.png|center|150px|''[[Anhanguera (pterosaur)|Anhanguera]]'']]
|-
| style="background:#E6E6E6;" | ''[[Araripedactylus]]''
| style="background:#E6E6E6;" | ''A. dehmi''
| style="background:#E6E6E6;" |
|
|-
| ''[[Araripesaurus]]''
| ''A. castilhoi''
|
|
|-
| ''[[Barbosania]]''<ref name=Elgin2011>Elgin & Frey, 2011</ref>
| ''B. gracilirostris''
|
|
|-
| ''[[Brasileodactylus]]''
| ''B. araripensis''
| 
| 
|-
| rowspan="2" | ''[[Cearadactylus]]''
| ''C. atrox''
| 
| rowspan=2 | [[File:Cearadactylus.jpg|center|150px]]
|-
| style="background:#fbdddb;"|"C." ''ligabuei''<ref name=UDM02>{{cite journal |last=Unwin |first=D. M. |year=2002 |title=On the systematic relationships of ''Cearadactylus atrox'', an enigmatic Early Cretaceous pterosaur from the Santana Formation of Brazil |journal=Mitteilungen Museum für Naturkunde Berlin, Geowissenschaftlichen Reihe |volume=5 |issue=1 |pages=1239–263|doi=10.5194/fr-5-239-2002 |doi-access=free |bibcode=2002FossR...5..239U }}</ref>
| 
|-
| ''[[Kariridraco]]''
| ''K. dianae''
| 
| [[File:Kariridraco by Júlia d’Oliveira.jpg|center|150px]]
|-
| ''[[Maaradactylus]]''
| ''M. kellneri''
| 
| [[File:Coloborhynchus spielbergi2.jpg|center|150px]]
|-
| ''[[Santanadactylus]]''
| 
* ''S. brasilensis''
* ?''S. pricei''
* ''S. spixi''
|
| [[File:Anhanguera santanae.jpg|150px|center]]
|-
| ''[[Tapejara (pterosaur)|Tapejara]]''
| ''T. wellnhoferi''
|
| [[File:Cast of Tapejara wellnhoferi - Pterosaurs Flight in the Age of Dinosaurs.jpg|center|150px]]
|-
| ''[[Thalassodromeus]]''
| ''T. sethi''
|
| [[File:Thalassodromeus.jpg|center|150px]]
|-
| ''[[Tropeognathus]]''
| ''T. mesembrinus''
|
| [[File:TropeognathusDB22.jpg|center|150px]]
|-
| ''[[Tupuxuara]]''
|
* ''T. deliradamus''
* ''T. leonardii''
* ''T. longicristatus''
|
| [[File:Tupuxuara.jpg|center|150px]]
|-
| ''[[Unwindia]]''
| ''U. trigonus''
|
|
|-
|}

=== Turtles ===
{| class="wikitable" align="center"
|-
! colspan="5" align="center" | '''Turtles'''
|-
! Genus !! Species !! Presence !! Notes !! Images
|-
| ''[[Santanachelys]]''
| ''S. gaffneyi''
|
| align=center | <ref>[https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=90355 ''Santanachelys gaffneyi''] at [[Fossilworks]].org</ref>
| [[File:Santanachelys.jpg|center|150px]]
|-
| ''[[Cearachelys]]''
| ''C. placidoi''
|
| align=center | <ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=128568 Juazeiro do Norte] at [[Fossilworks]].org</ref>
| [[File:Cearachelys placidoi MN 01.jpg|center|150px]]
|-
| ''[[Araripemys]]''
| ''A. barretoi''
| 
| align=center | <ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=128565 ''Araripemys barretoi'' type locality] at [[Fossilworks]].org</ref>
| [[File:Araripemys_barretoi.JPG|center|150px]]
|-
| ''[[Euraxemys]]''
| ''E. essweini''
| 
| align=center | <ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=83306 Crato] at [[Fossilworks]].org</ref>
| 
|-
| ''[[Brasilemys]]''
| ''B. josai''
| 
| align=center | <ref name=Chapada>[https://paleobiodb.org/classic/displayCollResults?collection_no=92290 Chapada do Araripe] at [[Fossilworks]].org</ref>
| 
|-
|}

{{paleobiota-key-compact}}

=== Fish ===
{{div col|colwidth=20em}}
* ''[[Araripelepidotes]]''
* ''[[Axelrodichthys|Axelrodichthys araripensis]]''.<ref name="Custódio&al.2017">{{cite journal|last=Custódio|first=M.A.|author2=Guaglio, F.|author3=Warren, L.V.|author4=Simões, M.G.|author5=Fürsich, F.T.|author6=Perinotto, J.A.|author7=Assine, M.L.|title=The transgressive-regressive cycle of the Romualdo Formation (Araripe Basin): Sedimentary archive of the Early Cretaceous marine ingression in the interior of Northeast Brazil|journal=Sedimentary Geology|year=2017|volume=359|issue=359|pages=1–15|doi=10.1016/j.sedgeo.2017.07.010|bibcode=2017SedG..359....1C|hdl=11449/175030|hdl-access=free}}</ref>
* ''[[Beurlenichthys|Beurlenichthys ouricuriensis]]''<ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=133574 Casa de Pedra] at [[Fossilworks]].org</ref>
* ''[[Brannerion]]''<ref name=Fara2005_p152/>
* ''[[Calamopleurus]]''<ref name=Fara2005_p152>Fara et al., 2005, p.152</ref>
* ''[[Cladocyclus]]''<ref name=Fara2005_p152/><ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=28052 Buxéxé, Santana do Cariri] at [[Fossilworks]].org</ref>
* ''[[Enneles|Enneles audax]]''<ref>[http://palaeo.gly.bris.ac.uk/Palaeofiles/Lagerstatten/santana/FosCrd25.htm ''Enneles audax'']</ref>
* ''[[Iemanja (fish)|Iemanja palma]]''<ref>[http://palaeo.gly.bris.ac.uk/Palaeofiles/Lagerstatten/santana/FosCrd6.htm ''Iemanja palma'']</ref>
* ''[[Lepidotes|Lepidotes wenzai]]''<ref name=Chapada/>
* ''[[Microdon|Microdon penalvai]]''<ref name=Chapada/>
* ''[[Notelops]]''<ref name=Fara2005_p152/>
* ''[[Obaichthys]]''<ref name=Chapada/>
* ''[[Oshunia|Oshunia brevis]]''<ref name=Chapada/>
* ''[[Placidichthys|Placidichthys bidorsalis]]''<ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=124310 ''Placidichthys'' type locality] at [[Fossilworks]].org</ref>
* ''[[Rhacolepis]]''<ref name=Fara2005_p152/>
* ''[[Iansan (fish)|Iansan beurleni]]''<ref name=Chapada/><ref>{{Cite journal |last=Maisey |first=John G. |date=2000-04-01 |title=Continental break up and the distribution of fishes of Western Gondwana during the Early Cretaceous |url=https://www.sciencedirect.com/science/article/pii/S0195667199901957 |journal=Cretaceous Research |language=en |volume=21 |issue=2 |pages=281–314 |doi=10.1006/cres.1999.0195 |bibcode=2000CrRes..21..281M |issn=0195-6671|url-access=subscription }}</ref>
* ''[[Santanaclupea|Santanaclupea silvasantosi]]''
* ''[[Tharrhias]]''<ref name=Fara2005_p152/>
* ''[[Tribodus|Tribodus limae]]''<ref name=Chapada/>
* ''[[Vinctifer]]''<ref name=Fara2005_p152/><ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=165422 Ze Gomes] at [[Fossilworks]].org</ref>
{{colend}}

== See also ==
{{div col}}
* [[List of fossil sites]] ''(with link directory)''
* [[List of dinosaur-bearing rock formations]]
* [[Araripe Basin]]
* [[Cerro Barcino Formation]]
* [[Elrhaz Formation]]
* [[Guarujá Formation]]
* [[Itapecuru Formation]]
* [[Mata Amarilla Formation]]
{{div col end}}

== References ==
{{Reflist}}

=== Bibliography ===
* {{cite journal |last1=Cavalcanti Duque |first1=Rudah Ruano |last2=Franca Barreto |first2=Alcina Magnólia |year=2018 |title=Novos Sítios Fossilíferos da Formação Romualdo, Cretáceo Inferior, Bacia do Araripe, Exu, Pernambuco, Nordeste do Brasil - New Fossiliferous Sites of the Romualdo Formation, Lower Cretaceous, Araripe Basin, Exu, Pernambuco, Northeast of Brazil |url=https://www.researchgate.net/publication/324900728 |journal=Anuário do Instituto de Geociências, UFRJ |volume=41 |pages=5–14 |doi=10.11137/2018_1_05_14 |accessdate=2018-10-06|doi-access=free }}
*{{Cite journal|last1=Elgin|first1=Ross A.|last2=Frey|first2=Eberhard|date=2011-04-20|title=A new ornithocheirid, Barbosania gracilirostris gen. et sp. nov. (Pterosauria, Pterodactyloidea) from the Santana Formation (Cretaceous) of NE Brazil|journal=[[Swiss Journal of Palaeontology]]|language=en|volume=130|issue=2|pages=259|doi=10.1007/s13358-011-0017-4|s2cid=89178816|issn=1664-2384|doi-access=free|bibcode=2011SwJP..130..259E }}
* {{cite journal |last1=Fabin |first1=Carlos E. |last2=Correia Filho |first2=Osvaldo J. |last3=Alencar |first3=Márcio L. |last4=Barbosa |first4=José A. |last5=de Miranda |first5=Tiago S. |last6=Neumann |first6=Virgínio H. |last7=Gomes |first7=Igor F. |last8=de Santana |first8=Felipe R. |year=2018 |title=Stratigraphic Relations of the Ipubi Formation: Siliciclastic-Evaporitic Succession of the Araripe Basin |url=http://www.scielo.br/pdf/aabc/v90n2s1/0001-3765-aabc-201820170526.pdf |journal=[[Anais da Academia Brasileira de Ciências]] |volume=90 |issue=2 suppl 1 |pages=2049–2071 |doi=10.1590/0001-3765201820170526 |pmid=29947671 |accessdate=2018-10-05}}
* {{cite journal |last1=Fara |first1=Emmanuel |last2=Saraiva |first2=Antônio Á.F. |last3=Campos |first3=Díogenes de Almeida |last4=Moreira |first4=João K.R. |last5=de Carvalho Siebra |first5=Daniele |last6=Kellner |author6-link=Alexander Kellner |first6=Alexander W.A. |year=2005 |title=Controlled excavations in the Romualdo Member of the Santana Formation (Early Cretaceous, Araripe Basin, northeastern Brazil): stratigraphic, palaeoenvironmental and palaeoecological implications |url=http://biogeosciences.u-bourgogne.fr/documents/articles_pdf/2005_Fara_PalaeogeogrPalaeoclimatPalaeoecol.pdf |journal=[[Palaeogeography, Palaeoclimatology, Palaeoecology]] |volume=218 |issue=1–2 |pages=145–160 |doi=10.1016/j.palaeo.2004.12.012 |bibcode=2005PPP...218..145F |accessdate=2018-10-06}}
* {{cite book |last1=Maisey |first1=J.G. |last2=Rutzky |first2=I. |last3=Blum |first3=S. |last4=Elvers |first4=W. |year=1991 |title=Laboratory Preparation Techniques. In Maisey, j:G. (ed): Santana Fossils: An Illustrated Atlas |publisher=Tfh Publications Inc. |pages=99–103 |isbn=0866225498}}
* {{cite book |last1=Martill |first1=David M. |last2=Bechly |first2=Günter |last3=Loveridge |first3=Robert F. |year=2007 |title=The Crato Fossil Beds of Brazil: Window into an Ancient World |url=https://books.google.com/books?id=5ZBh_-QvX2MC&pg=PA236 |publisher=[[Cambridge University Press]] |pages=236 |accessdate=2018-10-06 |isbn=978-1-139-46776-6}}
* {{cite journal |last=Martill |first=D.M |year=2007 |title=The age of the Cretaceous Santana Formation fossil Konservat Lagerstätte of north-east Brazil: a historical review and an appraisal of the biochronostratigraphic utility of its palaeobiota |url=https://doi.org/10.1016/j.cretres.2007.01.002 |journal=[[Cretaceous Research]] |volume=28 |issue=6 |pages=895–920 |doi=10.1016/j.cretres.2007.01.002 |bibcode=2007CrRes..28..895M |accessdate=2018-10-06|url-access=subscription }}
* {{cite book |last=Weishampel |first=David B. |author2=Paul M. Barrett |author3=Rodolfo A. Coria |author4=Jean Le Loeuff |author5=Xu Xing |author6=Zhao Xijin |author7=Ashok Sahni |author8=Elizabeth M. P. Gomani |author9=Christopher R. Noto |display-authors=1 |year=2004 |title=Dinosaur distribution (Early Cretaceous, South America) ''in:'' Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria |publisher=Berkeley: University of California Press |pages=563–570 |isbn=0-520-24209-2}}

== Further reading ==
* David M. Martill, 1993. ''Fossils of the Santana and Crato Formations, Brazil'' (Field Guide to Fossils no. 5) (The Palaeontological Association) {{ISBN|0-901702-46-3}}
* {{cite journal |last1=Neumann |first1=V.H. |last2=Borrego |first2=A.G. |last3=Cabrera |first3=L. |last4=Dino |first4=R. |year=2003 |title=Organic matter composition and distribution through the Aptian–Albian lacustrine sequences of the Araripe Basin, northeastern Brazil |journal=[[International Journal of Coal Geology]] |volume=54 |issue=1–2 |pages=21–40|doi=10.1016/S0166-5162(03)00018-1 |bibcode=2003IJCG...54...21N }} {{doi|10.1016/S0166-5162(03)00018-1}}
* {{cite journal |last1=Pinheiro |first1=Allysson P. |last2=Saraiva |first2=Antônio Á. |last3=Santana |first3=William |year=2014 |title=Shrimps from the Santana Group (Cretaceous: Albian): new species (Crustacea: Decapoda: Dendrobranchiata) and new record (Crustacea: Decapoda: Caridea) |journal=[[Anais da Academia Brasileira de Ciências]] |volume=86 |issue=2 |pages=663–670|doi=10.1590/0001-3765201420130338 |pmid=24789213 |doi-access=free }} {{doi|10.1590/0001-3765201420130338|doi-access=free}} {{PMID|24789213}} {{issn|0001-3765}}
* {{cite web |url=https://www.amnh.org/explore/news-blogs/on-exhibit-posts/pterosaurs-diorama-depicts-ancient-brazilian-coast |title=Pterosaurs Diorama Depicts Ancient Brazilian Coast |last= |first= |date=2014-04-14 |website=[[American Museum of Natural History]] |access-date=2019-12-21}}

[[Category:Romualdo Formation| ]]
[[Category:Geologic formations of Brazil]]
[[Category:Cretaceous Brazil]]
[[Category:Cretaceous paleontological sites of South America]]
[[Category:Paleontology in Brazil]]
[[Category:Mudstone formations of Brazil]]
[[Category:Deltaic deposits]]
[[Category:Environment of Ceará]]
[[Category:Environment of Pernambuco]]
[[Category:Environment of Piauí]]
[[Category:Landforms of Ceará]]
[[Category:Landforms of Pernambuco]]
[[Category:Landforms of Piauí]]
[[Category:Northeast Region, Brazil]]