Santana Formation

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Santana Formation
Stratigraphic range: Albian-?Cenomanian
Cretaceous Orthoptera fossil.jpg
Fossil of a cricket from the Santana Formation
Type Geological formation
Unit of Araripina Group
Overlies Crato Formation
Location
Country Brazil

The Santana Formation is a geologic Lagerstätte (undisturbed fossil accumulation) in northeastern Brazil's Araripe Basin where the states of Pernambuco, Piauí and Ceará come together. The geological 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 laid down between the late Early Cretaceous and early Late Cretaceous in a shallow inland sea. At that time, the South Atlantic was opening up in a long narrow shallow sea.

The Santana 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 (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.[1]

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 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 Santana Formation rocks.

Geology and dating[edit]

The Crato Formation has often historically been considered the lowest member of the Santana Formation (or, alternatively, the Araripina Formation). 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 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.[2][3]

The extent of the Crato unit and its relationship to the Santana 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.[2]

Notable taxa[edit]

Dinosaurs[edit]

Indeterminate remains of non-avian theropods, avialans, ornithischians, and possibly oviraptorosaurs have been found in Estado do Ceara, Brazil.[4]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Dinosaurs and Birds of the Santana Formation
Genus Species Presence Notes Images

Angaturama[4]

A. limai[4]

Geographically present in Estado do Ceara, Brazil.[4]

Spinosauridae. "Rostral portion of [a] skull."[5] Junior synonym of Irritator challengeri.

Irritator[4]

I. challengeri[4]

Geographically present in Estado do Ceara, Brazil.[4]

Spinosauridae. "Partial skull."

Mirischia[4]

M. asymmetrica[4]

Geographically present in Estado do Ceara, Brazil.[4]

Compsognathidae

Santanaraptor[4]

S. placidus[4]

Geographically present in Estado do Ceara, Brazil.[4]

"Partial postcranium."[6]

Pterosaurs[edit]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Pterosaurs of the Santana Formation
Genus Species Presence Description Images
Anhanguera * A. blittersdorffi
  • A. santanae
  • A. araripensis
  • A. robustus
  • A. piscator
  • A. spielbergi
Romualdo Member Includes "Pricesaurus"
Araripedactylus Araripedactylus dehmi
Araripesaurus Araripesaurus castilhoi
Barbosania[7] Barbosania gracilirostris
Brasileodactylus Brasileodactylus araripensis Romualdo Member
Cearadactylus Cearadactylus atrox Romualdo Member
"Cearadactylus" "Cearadactylus" ligabuei Romualdo Member
Maaradactylus Maaradactylus kellneri Romualdo Member
Santanadactylus
  • Santanadactylus brasilensis
  • ?Santanadactylus pricei
  • "S." spixi
Tapejara Tapejara wellnhoferi

Thalassodromeus

Thalassodromeus sethi

Tropeognathus

Tropeognathus mesembrinus

Tupuxuara

  • T. deliradamus
  • T. leonardii
  • T. longicristatus

Romualdo Member

Unwindia Unwindia trigonus

Turtles[edit]

Turtles of the Santana Formation
Genus Species Presence Description Images

Santanachelys

Protostegidae, Cryptodira

Fish[edit]

See also[edit]

References[edit]

  1. ^ Maisey, J.G., Rutzky, I., Blum, S. & W. Elvers (1991): Laboratory Preparation Techniques. In Maisey, j:G. (ed): Santana Fossils: An Illustrated Atlas, Tfh Pubns Inc.ISBN 0866225498. pp 99–103.
  2. ^ a b Martill, D.M., Bechly, G. and Loveridge, R.F. (2007). The Crato fossil beds of Brazil: window into an ancient world. Cambridge University Press. ISBN 0-521-85867-4, ISBN 978-0-521-85867-0
  3. ^ Martill, D.M. (2007). "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". Cretaceous Research. 28 (6): 895–920. doi:10.1016/j.cretres.2007.01.002. 
  4. ^ a b c d e f g h i j k l m Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, South America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 563–570. ISBN 0-520-24209-2.
  5. ^ "Table 4.1," in Weishampel, et al. (2004). Page 73.
  6. ^ "Table 5.1," in Weishampel, et al. (2004). Page 114.
  7. ^ Ross A. Elgin and Eberhard Frey (2011) A new ornithocheirid, Barbosania gracilirostris gen. et sp. nov. (Pterosauria, Pterodactyloidea) from the Santana Formation (Cretaceous) of NE Brazil Swiss Journal of Palaeontology (advance online publication) doi:10.1007/s13358-011-0017-4 [1]

External links[edit]

Further reading[edit]

  • David A. Grimaldi (ed.) 1990. Insects from the Santana Formation, Lower Cretaceous, of Brazil, Bulletin of the American Museum of Natural History no. 195
  • John G. Maisey (ed.) 1991. Santana Fossils – An Illustrated Atlas (T.H.F. Publ.)
  • 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
  • David M. Martill, Günter Bechly and Robert F. Loverridge (eds) 2007. The Crato Fossil Beds of Brazil: Window into an Ancient World (Cambridge University Press) ISBN 978-0-521-85867-0