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]
at 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 ...
.org
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