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 (top) and Santanadactylus (bottom) from the Romualdo Formation
| type = Geological formation
| age = Early Albian
~{{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 & Arajara Formations
| overlies = Crato & Ipubi Formations
| 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 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 Formation, named after the village of Santana do Cariri, lies at the base of the Araripe Plateau. It was discovered by Johann Baptist von Spix in 1819. The strata were deposited during the Aptian stage of the Early Cretaceous in a lacustrine rift basin with shallow marine incursions of the 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 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 invertebrates, and crocodylomorphs. Even dinosaurs are represented (Spinosauridae, Tyrannosauroidea, Compsognathidae). The unusual taphonomy of the site resulted in limestone 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.Maisey et al., 1991, pp. 99–103
Local mining activities for cement and construction damage the sites. 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.{{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}}
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
File:Ipubi and Romualdo Formations - outcrop.jpg
{{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 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.Martill et al., 2007Martill, 2007
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.
Fossil content
= Archosaurs =
Indeterminate remains of non-avian theropods, avialans, ornithischians, and possibly oviraptorosaurs have been found in Ceara state, Brazil. The oviraptorosaurian remains have been re-identified as megaraptoran fossils.{{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}}
== Dinosaurs ==
== Crocodylomorphs ==
| class="wikitable" align="center" | ||||
| colspan="5" align="center" | Crocodylomorphs | ||||
|---|---|---|---|---|
| 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. | ||||
| Caririsuchus
|C. camposi |Romualdo Formation |A peirosaurid crocodyliform. | |
= Pterosaurs =
= Turtles =
| class="wikitable" align="center" | ||||
| colspan="5" align="center" | Turtles | ||||
|---|---|---|---|---|
| Genus | Species | Presence | Notes | Images |
| Santanachelys
| S. gaffneyi | | align=center | [https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=90355 Santanachelys gaffneyi] at Fossilworks.org | ||||
| Cearachelys
| C. placidoi | | align=center | [https://paleobiodb.org/classic/displayCollResults?collection_no=128568 Juazeiro do Norte] at Fossilworks.org | ||||
| Araripemys
| A. barretoi | | align=center | [https://paleobiodb.org/classic/displayCollResults?collection_no=128565 Araripemys barretoi type locality] at Fossilworks.org | ||||
| Euraxemys
| E. essweini | | align=center | [https://paleobiodb.org/classic/displayCollResults?collection_no=83306 Crato] at Fossilworks.org | | ||||
| Brasilemys
| B. josai | | align=center | [https://paleobiodb.org/classic/displayCollResults?collection_no=92290 Chapada do Araripe] at Fossilworks.org | |
{{paleobiota-key-compact}}
= Fish =
{{div col|colwidth=20em}}
- Araripelepidotes
- Axelrodichthys araripensis.{{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}}
- Beurlenichthys ouricuriensis[https://paleobiodb.org/classic/displayCollResults?collection_no=133574 Casa de Pedra] at Fossilworks.org
- Brannerion
- CalamopleurusFara et al., 2005, p.152
- Cladocyclus[https://paleobiodb.org/classic/displayCollResults?collection_no=28052 Buxéxé, Santana do Cariri] at Fossilworks.org
- Enneles audax[http://palaeo.gly.bris.ac.uk/Palaeofiles/Lagerstatten/santana/FosCrd25.htm Enneles audax]
- Iemanja palma[http://palaeo.gly.bris.ac.uk/Palaeofiles/Lagerstatten/santana/FosCrd6.htm Iemanja palma]
- Lepidotes wenzai
- Microdon penalvai
- Notelops
- Obaichthys
- Oshunia brevis
- Placidichthys bidorsalis[https://paleobiodb.org/classic/displayCollResults?collection_no=124310 Placidichthys type locality] at Fossilworks.org
- Rhacolepis
- Iansan beurleni{{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 }}
- Santanaclupea silvasantosi
- Tharrhias
- Tribodus limae
- Vinctifer[https://paleobiodb.org/classic/displayCollResults?collection_no=165422 Ze Gomes] at Fossilworks.org
{{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:Geologic formations of Brazil
Category:Cretaceous paleontological sites of South America
Category:Paleontology in Brazil
Category:Environment of Pernambuco