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Cretaceous locust fossil

Fossil of a locust from the Santana Formation.

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. The strata were laid down during the early Cretaceous, specifically during the late Aptian to Cenomanian, 108 to 92 million years ago, 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: 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.

Crato memberEdit

The Crato Member is the product of a single phase in the Santana Formation, where complicated sequence of sediment strata reflect changeable conditions in the opening sea.

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 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.

Notable taxaEdit

DinosaursEdit

Indeterminate remains of non-avian theropods, avialans, ornithischians, and possibly oviraptorosaurs have been found in Estado do Ceara, Brazil.[1]

Dinosaurs and Birds of the Santana Formation
Genus Species Presence Notes Images

Angaturama[1]

A. limai[1]

Geographically present in Estado do Ceara, Brazil.[1]

Spinosauridae. "Rostral portion of [a] skull."[2] Junior synonym of Irritator challengeri.

Irritator[1]

I. challengeri[1]

Geographically present in Estado do Ceara, Brazil.[1]

Spinosauridae. "Partial skull."[2]

Mirischia[1]

M. asymmetrica[1]

Geographically present in Estado do Ceara, Brazil.[1]

Compsognathidae

Santanaraptor[1]

S. placidus[1]

Geographically present in Estado do Ceara, Brazil.[1]

"Partial postcranium."[3]

PterosaursEdit

Pterodactyls of the Santana Formation
Genus Species Presence Description Images

Araripedactylus

Araripedactylus dehmi

Araripesaurus

Araripesaurus castilhoi

Barbosania[4]

Barbosania gracilirostris

Cearadactylus

Cearadactylus atrox

"Pricesaurus"

"Pricesaurus megalodon"

Santanadactylus

Santanadactylus brasilensis

Tapejara

Tapejara wellnhoferi

Thalassodromeus

Thalassodromeus sethi

Tropeognathus

Tropeognathus mesembrinus

Tupuxuara

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

Romualdo Member

TurtlesEdit

Turtles of the Santana Formation
Genus Species Presence Description Images

Santanachelys

Protostegidae, Cryptodira

See also Edit

External linksEdit

Further readingEdit

  • 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

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