The Ankazomihaboka Formation is a

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...

geologic formation in the

Mahajanga Basin Mahajangā (French: Majunga) is a city and an administrative district on the northwest coast of Madagascar. The city of Mahajanga (Mahajanga I) is the capital of the Boeny Region. The district (identical to the city) had a population of 258,068 ...

of northwestern

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

. The formation comprises

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone and shale. Most of the particles of which the stone is composed are less than and are too small to ...

s and

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s deposited in a

fluvial A river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of its course if it ru ...

lacustrine A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from t ...

environment.MAD 96
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org The formation is overlain by the Marovoay Beds and overlies

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

.Rogers et al., 2000, p.280

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

remains diagnostic to the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

level are among the fossils that have been recovered from the formation.Weishampel, et al. (2004). "Dinosaur distribution" Pp. 517-607. in Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. . " Pp. 517-607.

Fossil content

* "Titanosaurus" madagascariensis * ''

Majungasaurus crenatissimus ''Majungasaurus'' (; ) is a genus of abelisaurid theropod dinosaur that lived in Madagascar from 70 to 66 million years ago, at the end of the Cretaceous Period (geology), Period, making it one of the last-known non-avian dinosaurs that went e ...

'' (theropod indet.) * '' Axelrodichthys sp.'' * '' Ferganoceratodus madagascariensis''

References

Bibliography

* {{citation , last1=Rogers , first1=Raymond R. , last2=Hartman , first2=Joseph H. , last3=Krause , first3=David W. , year=2000 , title=Stratigraphic Analysis of Upper Cretaceous Rocks in the Mahajanga Basin, Northwestern Madagascar: Implications for Ancient and Modern Faunas , url=https://www.researchgate.net/publication/12547766 , journal=

Journal of Geology ''The Journal of Geology'' publishes research on geology, geophysics, geochemistry, sedimentology, geomorphology, petrology, plate tectonics, volcanology, structural geology, mineralogy, and planetary sciences. Its content ranges from planetary ev ...

, volume=108 , issue=3 , pages=275–301 , doi=10.1086/314403 , pmid=10769157 , bibcode=2000JG....108..275R , accessdate=2018-08-30

Fossil content

See also

References

Bibliography

Further reading