Coordinates: 16°36′S 47°00′E / 16.6°S 47.0°E / -16.6; 47.0

Isalo III Formation

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Isalo III Formation
Stratigraphic range: Bajocian-Bathonian
~168–165 Ma
↓
TypeGeological formation
Sub-unitsIsalo IIIa or Beronono Formation
Isalo IIIb or Sakaraha Formation
OverliesIsalo II Formation (unconformity)
Lithology
PrimarySandstone
OtherClaystone, marl
Location
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Approximate paleocoordinatesLua error: callParserFunction: function "#coordinates" was not found.
RegionMahajanga & Fianarantsoa Provinces
CountryMadagascar
ExtentMahajanga Basin

The Isalo III Formation is a geological formation in Madagascar, off the eastern coast of Africa. It dates back to the Middle Jurassic.[1] The use of the term "Isalo III" is somewhat controversial as the two prior units Isalo I and II are Triassic cross-bedded sandstone units that form a continuous depositional sequence, while the "Isalo III" sandstones are not part of the same depositional sequence, and were deposited considerably later. and are perhaps better treated as part of several separate formations.[2] It is traditionally divided into two subunits the lower, Bajocian aged Isalo IIIa unit also known as the Beronono Formation and the upper, Bathonian aged Isalo IIIb unit also known as the Sakaraha Formation or Sakahara Formation.[3] The Sakaraha Formation consists of sandstones, marls and carbonates and represents a coastal plain environment, and is laterally equivalent to the predominantly carbonate Bemaraha Formation, which represents a coastal barrier lagoon complex.[2] The formation is found in the northwest and in the southeast of the country and has provided a variety of fossils.

Fossil content

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Pterosaur teeth referred to Rhamphorhynchoidea are known from the formation.[4]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Dinosaurs

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Sauropods

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Sauropods of the Isalo III Formation
Genus Species Location Stratigraphic position Material Notes Images
Archaeodontosaurus A. descouensi Ambondromamy, Majunga Teeth and mandible A eusauropod sauropod
File:Archaeodontosaurus dent fond.jpg
Lapparentosaurus[5] L. madagascariensis Faritany Majunga "More than [four] partial skeletons lacking skulls and teeth" A cetiosaurid sauropod
File:Lapparentosaurus femur.png
Narindasaurus[6] N. thevenini Ankinganivalaka Right tibia, left pubis, caudal vertebrae, right fibula A turiasaurian sauropod
File:Lapparentosaurus madagascariensis left pubis.jpg
?Diplodocoidea Indet[7] Indeterminate IIIb Teeth
?Titanosaurifomes Indet[7] Indeterminate IIIb Teeth

Theropoda

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Theropods of the Isalo III Formation
Genus Species Location Stratigraphic position Material Notes Images
Abelisauridae indet. Indeterminate IIIb MSNM V5778, V5779, V5781, V5789, V5799, V5809; FC-DPV 3531; PVL 3672, 515 4062-1 to 4062-4, 4173, 4174, 4175; NHMUK R4190 - all isolated shed crowns[8] The earliest record of Abelisauridae
Theropoda Indet. Indeterminate IIIb MSNM V6234 "a large, serrated tooth crown"[9] MSNM V5804 vertebra, isolated teeth representing 8 morphotypes[10]
Ceratosauria Indet. Indeterminate IIIb MSNM V6235 Pedal ungual[9]

Crocodyliformes

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Crocodyliformes of the Isalo III Formation
Genus Species Location Stratigraphic position Material Notes Images
Andrianavoay[11] A. baroni IIIb A machimosaurine thelattosuchian
Razanandrongobe[3] R. sakalavae IIIb A notosuchian
File:Razanandrongobe-fig2-MNHTspecimens.jpg

See also

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References

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  1. ^ Weishampel et al., 2004, pp.542-543
  2. ^ a b Geiger et al., 2004
  3. ^ a b Dal Sasso et al., 2017
  4. ^ Dal Sasso C. & Pasini G., 2003 - First record of pterosaurs (Pterosauria, Archosauromorpha, Diapsida) in the Middle Jurassic of Madagascar. Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale in Milano, 144 (II): 281-296.
  5. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  6. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  7. ^ a b Bindellini & Dal Sasso, 2019
  8. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  9. ^ a b Maganuco S, Cau A, Dal Sasso C, Pasini G. 2007. Evidence of large theropods from the Middle Jurassic of the Mahajanga Basin, NW Madagascar, with implications for ceratosaurian pedal ungual evolution. Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale in Milano 148(II):261-271
  10. ^ Maganuco S., Cau A. & Pasini G.. 2005 First description of theropod remains from the Middle Jurassic (Bathonian) of Madagascar. Atti Soc. it. Sci. nat. Museo civ. Stor. nat. Milano. 146, 165–202.
  11. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).

Bibliography

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  • Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  • Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  • Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  • Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  • Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).

Further reading

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  • É. Buffetaut. 2005. A new sauropod dinosaur with prosauropod-like teeth from the Middle Jurassic of Madagascar. Bulletin de la Société Géologique de France 176(5):467-473
  • S. Maganuco, C. Dal Sasso, and G. Pasini. 2006. A new large predatory archosaur from the Middle Jurassic (Bathonian) of Madagascar. Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano 147(1):19-51
  • J. J. Flynn, J. M. Parrish, B. Rakotosamimanana, W. F. Simpson, and A. R. Wyss. 1999. A Middle Jurassic mammal from Madagascar. Nature 401:57-60
  • A. Ogier. 1975. Etude de Nouveaux Ossements de Bothriospondylus (Sauropode) d'un Gisement du Bathonien de Madagascar [Study of New Bones of Bothriospondylus (Sauropod) from a Locality from the Bathonian of Madagascar]. Sciences Naturelles, Université de Paris VI 1-111
  • M. Collignon. 1954. Decouverte de dinosauriens a Tsinjorano, district d'Ambato-Boeni [Discovery of dinosaurs at Tsinjorano, Ambato-Boeni district]. Bulletin de l'Académie Malgache 31:59-61
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