The Isalo III Formation is a geological formation in Madagascar, off the eastern coast of Africa. It dates back to the Middle Jurassic. 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. 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. 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. The formation is found in the northwest and in the southeast of the country and has provided a variety of fossils.

Fossil content

Pterosaur teeth referred to Rhamphorhynchoidea are known from the formation.

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon MorphotaxonNotes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
TaxonReclassified taxonTaxon falsely reported as presentDubious taxon or junior synonymIchnotaxonOotaxonMorphotaxon

Dinosaurs

Sauropods

Sauropods of the Isalo III Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
ArchaeodontosaurusA. descouensiAmbondromamy, MajungaTeeth and mandibleA eusauropod sauropod
LapparentosaurusL. madagascariensisFaritany Majunga"More than [four] partial skeletons lacking skulls and teeth"A cetiosaurid sauropod
NarindasaurusN. theveniniAnkinganivalakaRight tibia, left pubis, caudal vertebrae, right fibulaA turiasaurian sauropod
?Diplodocoidea IndetIndeterminateIIIbTeeth
?Titanosaurifomes IndetIndeterminateIIIbTeeth

Theropoda

Theropods of the Isalo III Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Abelisauridae indet.IndeterminateIIIbMSNM 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 crownsThe earliest record of Abelisauridae
Theropoda Indet.IndeterminateIIIbMSNM V6234 "a large, serrated tooth crown" MSNM V5804 vertebra, isolated teeth representing 8 morphotypes
Ceratosauria Indet.IndeterminateIIIbMSNM V6235 Pedal ungual

Crocodyliformes

Crocodyliformes of the Isalo III Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
AndrianavoayA. baroniIIIbA machimosaurine thelattosuchian
RazanandrongobeR. sakalavaeIIIbA notosuchian

See also

Bibliography

  • Royo Torres, Rafael; Cobos, Alberto; Mocho, Pedro; Alcalá, Luis (2021). . Zoological Journal of the Linnean Society. 191: 201–227. doi:.
  • Bindellini, Gabriele; Sasso, Cristiano Dal (2019). "Sauropod teeth from the Middle Jurassic of Madagascar, and the oldest record of Titanosauriformes". Papers in Palaeontology. 7: 137–161. doi:. S2CID .
  • Dal Sasso, Cristiano; Pasini, Giovanni; Fleury, Guillaume; Maganuco, Simone (2017). . PeerJ. 5 e3481. doi:. PMC . PMID .
  • Geiger, Markus; Clark, David Norman; Mette, Wolfgang (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. Bibcode:. doi:.
  • Weishampel, David B.; Dodson, Peter; Osmólska, Halszka, eds. (2004). (2nd ed.). Berkeley: University of California Press. pp. 1–880. ISBN 9780520941434.
  • Thevenin, A (1907). (PDF). Annales de Paléontologie. 2: 121–136.

Further reading

  • 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