Santana formation

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The Santana Formation is one of the most important fossil sites in the world. It is located in the Santana region in eastern Brazil in the Araripe Basin on the border between the states of Pernambuco , Piauí and Ceará . The find area is at the foot of the Araripe Plateau, the highest point in the Araripe Basin with a maximum height of 600 to 900 meters and an extension of around 200 kilometers from east to west. The fossils of the Santana Formation date from the early Cretaceous period about 110 million years ago.

The first fossils of the formation were discovered by the two Bavarian researchers Johann Baptist von Spix and Carl Friedrich Philipp von Martius in 1819 when they were exploring this then completely unexplored region and came across very well-preserved fossils of fish. The news of this find spread very quickly and reached paleontologists all over the world. The first pterosaur ( araripesaurus castilhoi ) was 1971 by Llewellyn Ivor Price scientifically (1905-1980) described .

Geology of the Araripe Basin

The Santana Formation formed during the Lower Cretaceous approximately 90 to 110 million years ago. At that time, the giant continent of Gondwana broke up and the two parts of South America and Africa grew apart. Accordingly, the living conditions changed rapidly in time and space at the time of the deposition, which is reflected in the sediments of the Santana Formation.

The sedimentary rocks are stored on a rock base of Proterozoic metamorphic rocks , mainly gneiss , and volcanic rocks . The sequence begins with the Cariri formation as the lowest layer element, which consists primarily of sandstone and gravel . This is followed by the Missao Velha Formation with red and green sandstone (Mudstone) and the Crato Formation, in which the sandstone has a very high proportion of organic matter and is interlocked with plate limestone. The next layer, the Ipubi Formation, consists of evaporite rocks , which are salt rocks that are classified as chemical sediments. This is followed by the Batateiras formation, which consists mainly of fine sand and gravel.

The Crato member, consisting of thin-plate limestone, is the older of the fossil-bearing strata members. It mainly contains fossils of terrestrial arthropods and plants. The actual Santana formation (also Romualdo layer member) with the well-known fish fossils lies above and consists essentially of fine-grained sandstone with well-developed fossil horizons, mostly in hard lime tubers. The end of the sequence of layers is formed by the exu formation characterized by further sandstones, coarse sand and gravel (nomenclature according to Martill, 1993).

Fossils of the Santana Formation

The Santana Formation mainly contains fossils of various fish species from the early Cretaceous period. There are also Santana fossils of various amphibians , reptiles (such as crocodiles and turtles ), pterosaurs ( Ornithocheirus and Tapejara ) and dinosaurs . Even insects , scorpions , spiders and flowering plants and ferns found in remarkable quality. The good preservation of the fossils and the attention to detail is mainly due to the rapid sedimentation and the fine grain of the substrate.

Fish fossils are particularly well known, abundant and important. This includes many species of bony fish , but also sharks and rays as well as coelacids . Many of these fish were discovered only here, some (such as the sprat-like Dastilbe crandalli ) also on the west coast of the African continent, whereby they are cited as evidence of the Gondwana theory.

Pterosaurs from the Santana Formation:

The formation is a particularly rich site for pterosaurs. Nowhere else in the world have so many different pterosaurs of the lower Cretaceous been discovered as here. In doing so, specimens of almost all pterosaur groups known at the time were discovered, some taxa are even only known through these specimens.

Among the dinosaurs it is mainly theropods that were discovered in the Santana Formation; For example, the Santana raptor discovered in 1999 and the spinosaurids Angaturama limai and Irritator challengeri , which, however, are very likely to represent fossils of the same species and thus synonyms.

Also noteworthy are the finds of some turtles in this place, such as the oldest known sea ​​turtle Santanachelys gaffneyi as well as the Araripemydidae Araripemys barretoi and the Bothremydidae Cearachelys placidoi .

There are thousands of finds of very well-preserved arthropods such as spiders, scorpions and insects ( dragonflies , two-winged birds , cicadas, etc.), as do the prints of flowering plants and ferns .


It is very likely that the Santana Formation originated from the sedimentation of a shallow inland lake that was filled with fresh or brackish water. With regard to salinity , there has been disagreement so far, mainly due to the fossil record, some fish speak for salt-free or low-salt water, others for salt water. The insect finds are more an indication of fresh water, the discovery of the Santanachelys gaffneyi in turn suggests salt water. The theory that it was a brackish lagoon that was connected to the sea is therefore most widely recognized . The climate was tropical and warm and is said to have largely corresponded to today's climate in Brazil.


  • David A. Grimaldi et al. a .: Insects from the Santana Formation, Lower Cretaceous, of Brazil. (PDF; 54.5 MB) In: Bulletin of the American Museum of Natural History. No. 195, 1990.
  • John G. Maisey (Ed.): Santana Fossils. An Illustrated Atlas. TFH Publications, Neptune 1991, ISBN 0-86622-549-8 .
  • David M. Martill: Fossils of the Santana and Crato Formations, Brazil. The Palaeontological Association, London 1993, ISBN 0-901702-46-3 , ( Field Guide to Fossils. 5).
  • David M. Martill, Günter Bechly, Robert F. Loverridge (Eds.): The Crato Fossil Beds of Brazil. Window into an Ancient World. Cambridge University Press, Cambridge 2007, ISBN 978-0-521-85867-0 .

Individual evidence

  1. ^ SP Davis & DM Martill: The Gonorynchiform Fish Dastilbe from the Lower Cretaceous of Brazil. In: Palaeontology. Volume 42, Part 4, 1999, pp. 715-740 ( digital copy )

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