Isalo III Formation

Isalo III Formation
Stratigraphic range: Bajocian-Bathonian
↓
Type Geological formation
Unit of Isalo Group
Sub-units Isalo IIIa / Beronono Formation, Isalo IIIb / Sakaraha Formation
Overlies Isalo II Formation
Lithology
Primary Sandstone
Other Claystone, marl
Location
Coordinates 16°36′S 47°00′E / 16.6°S 47.0°E / -16.6; 47.0Coordinates: 16°36′S 47°00′E / 16.6°S 47.0°E / -16.6; 47.0
Approximate paleocoordinates 23°54′S 25°06′E / 23.9°S 25.1°E / -23.9; 25.1
Region Mahajanga & Fianarantsoa Provinces
Country  Madagascar
Extent Mahajanga Basin
Outcrops of the formation in Madagascar

The Isalo III Formation is a geological formation in Madagascar, off the eastern coast of Africa. It dates back to the Middle Jurassic.[1] It is 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.[2] The formation comprises claystones, sandstones and marls deposited in a terrestrial environment. The formation is found in the northwest and in the southeast of the country and has provided a variety of fossils.

Vertebrate fauna

Dinosaurs

Dinosaurs of the Isalo III Formation
Taxon Species Presence Notes Images

?Allosauroidea[1]

 Indeterminate Geographically located in Faritany Majunga, Madagascar.[1]
Lapparentosaurus[1] L. madagascariensis Geographically located in Faritany Majunga, Madagascar.[1]

"More than [four] partial skeletons lacking skulls and teeth."[3]
Archaeodontosaurus A. descouensi Ambondromamy, Majunga, Madagascar Teeth and mandible
Sauropoda[1] Indeterminate Geographically located in Faritany Majunga, Madagascar.[1]

(=Bothriospondylus madagascariensis) [1] "Isolated vertebrae, limb elements of at least [ten] individuals."[4]

Crocodyliformes

Crocodyliformes of the Isalo III Formation
Taxon Species Presence Notes Images
Razanandrongobe[5] R. sakalavae IIIb Notosuchian

Mammals

Mammals of the Isalo III Formation
Taxon Species Presence Notes Images
AmbondroA. mahaboIIIb[6]

See also

References

  1. 1 2 3 4 5 6 7 8 Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Africa)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 542-543. ISBN 0-520-24209-2.
  2. ↑ Geiger, Markus; Clark, David Norman; Mette, Wolfgang (March 2004). "Reappraisal of the timing of the breakup of Gondwana based on sedimentological and seismic evidence from the Morondava Basin, Madagascar". Journal of African Earth Sciences. 38 (4): 363–381. doi:10.1016/j.jafrearsci.2004.02.003. ISSN 1464-343X.
  3. ↑ "Table 13.1," in Weishampel, et al. (2004). Page 266.
  4. ↑ "Table 13.1," in Weishampel, et al. (2004). Page 270.
  5. ↑ Dal Sasso, Cristiano; Pasini, Giovanni; Fleury, Guillaume; Maganuco, Simone (2017-07-04). "Razanandrongobe sakalavae, a gigantic mesoeucrocodylian from the Middle Jurassic of Madagascar, is the oldest known notosuchian". PeerJ. 5: e3481. doi:10.7717/peerj.3481. ISSN 2167-8359. PMC 5499610. PMID 28690926.
  6. ↑ Ambondromahabo, M-8 at Fossilworks.org

Further reading

  • E. Buffetaut. 2005. A new sauropod dinosaur with prosauropod-like teeth from the Middle Jurassic of MadagascarBulletin de la Societé Géologique de France. Bulletin de la Societé Géologique de France 176(5):467-473
  • 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
  • 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
  • S. Maganuco, A. Cau, C. Dal Sasso and G. Pasini. 2007. Evidence of large theropods from the Middle Jurassic of the Mahajanga Basin, NW Madagascar, with implications for ceratosaurian peal ungual evolution. Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano 148(2):261-271
  • 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
  • S. Maganuco, A. Cau, and G. Pasini. 2005. First description of theropod remains from the Middle Jurassic (Bathonian) of Madagascar. Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano 146(2):165-202
  • 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
  • C. Dal Sasso and G. Pasini. 2003. First record of pterosaurs (Diapsida, Archosauromorpha, Pterosauria) in the Middle Jurassic of Madagascar. Atti della Societa Italiana di Scienze Naturali e del Museo Civico di Storia Naturale in Milano 144:281-296
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