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The Ambolafotsy Formation is a Turonian aged geological formation in the Diego Basin of Antsiranana Province in Madagascar. It is a mostly terrestrial unit deposited during a marine regression close to the shoreline. The dinosaur '' Dahalokely'' has been discovered in the formation.


Description

The section containing the Dahalokely site is informally termed the "Ambolafotsy Formation" and is divided into lower, middle (containing the type locality), and upper units. The lower unit has produced several biostratigraphically informative foraminifera, including '' Whiteinella aprica'', ''W. baltica'', '' Helvetoglobotruncana praehelvetica'', and ''H. helvetica'', and the nannofossil '' Quadrum gartneri'', placing the sample within the ''Q. gartneri'' and ''H. helvetica'' zones. The upper unit contains the
ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...
'' Subprionocyclus neptuni''. The sediments of most of the middle unit of the Ambolafotsy Formation are interpreted as terrestrial, deposited during a marine regression. Carbonized plant fragments are quite common in the middle unit, along with claystones, shales, and cross-bedded sandstones. Marine microfossils and macrofossils are generally absent, although a deposit of ostreids several meters above the type locality for ''Dahalokely'' suggests that the area was deposited close to the shoreline.Near Ampandriambengy, around the area of Antsiranana
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Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...
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See also

* List of fossiliferous stratigraphic units in Madagascar * Geology of Madagascar


References

{{reflist Geologic formations of Madagascar Cretaceous Madagascar Paleontology in Madagascar Upper Cretaceous Series of Africa Turonian Stage Shale formations Sandstone formations Formations