{{Short description|Geological formation in Madagascar}}{{Infobox rockunit | name = Isalo III Formation | period = Bathonian | age = Bathonian-Callovian<br>~{{fossilrange|168|165}} | image = | imagesize = | caption = | type = Geological formation | prilithology = Sandstone | otherlithology = Claystone, marl | unitof = | subunits = Isalo IIIa or Beronono Formation<br>Isalo IIIb or Sakaraha Formation | underlies = | overlies = Isalo II Formation (unconformity) | thickness = | area = | map = {{Location map+ | Madagascar | relief = 1 | width = 250 | float = center | caption = | places = {{Location map~ | Madagascar | lat_deg = -21.4 | lon_deg = 47.5 | mark = Blue pog.svg | marksize = 10 }} {{Location map~ | Madagascar | lat_deg = -15.6 | lon_deg = 47.7 | mark = Blue pog.svg | marksize = 10 }} {{Location map~ | Madagascar | lat_deg = -14.6 | lon_deg = 48.0 | mark = Blue pog.svg | marksize = 10 }} {{Location map~ | Madagascar | lat_deg = -16.4 | lon_deg = 47.2 | mark = Blue pog.svg | marksize = 10 }} {{Location map~ | Madagascar | lat_deg = -17.0 | lon_deg = 46.2 | mark = Blue pog.svg | marksize = 10 }} }} | map_caption = | location = | coordinates = {{coord|16.6|S|47.0|E|display=inline,title}} | paleocoordinates = {{coord|23.9|S|25.1|E|display=inline}} | region = Mahajanga & Fianarantsoa Provinces | country = Madagascar | extent = Mahajanga Basin }} The '''Isalo III Formation''' is a geological formation in Madagascar, off the eastern coast of Africa. It dates back to the Middle Jurassic.<ref name="jurassicdistribution">Weishampel et al., 2004, pp.542-543</ref> 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.<ref name=":1">Geiger et al., 2004</ref> 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'''.<ref name=":0" /> 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.<ref name=":1" /> 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.<ref>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.</ref>

{{paleobiota-key-compact}}

=== Dinosaurs ===

==== Sauropods ==== {| class="wikitable" align="center" |- ! colspan="7" align="center" | 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 | center|150px |- | ''Lapparentosaurus''<ref>{{cite journal |author1=Miky Lova Tantely Raveloson |author2=Neil D. L. Clark |author3=Armand H. Rasoamiaramana |year=2019 |title=New information on the Madagascan Middle Jurassic sauropod ''Lapparentosaurus madagascariensis'' |journal=Geosciences |volume=9 |issue=12 |article-number=498 |doi=10.3390/geosciences9120498 |bibcode=2019Geosc...9..498R |doi-access=free |url=https://eprints.gla.ac.uk/210400/1/210400.pdf }}</ref> | ''L. madagascariensis'' | Faritany Majunga | | "More than [four] partial skeletons lacking skulls and teeth" | A cetiosaurid sauropod | center|frameless |- | ''Narindasaurus''<ref>{{Cite journal|author1=Rafael Royo-Torres |author2=Alberto Cobos |author3=Pedro Mocho |author4=Luis Alcalá |year=2020 |title=Origin and evolution of turiasaur dinosaurs set by means of a new 'rosetta' specimen from Spain |journal=Zoological Journal of the Linnean Society |volume=191 |issue=1 |pages=201–227 |doi=10.1093/zoolinnean/zlaa091 |doi-access=free |url=http://publication.plazi.org/id/FFCFFF96FFDBFF84FFE5F109A843CC31 }}</ref> | ''N. thevenini'' | Ankinganivalaka | | Right tibia, left pubis, caudal vertebrae, right fibula | A turiasaurian sauropod | center|frameless |- | ?Diplodocoidea indet.<ref name=":2">Bindellini & Dal Sasso, 2019</ref> | Indeterminate | IIIb | Teeth | | |- | ?Titanosaurifomes indet.<ref name=":2" /> | Indeterminate | IIIb | Teeth | | |- |}

==== Theropoda ==== {| class="wikitable" align="center" |- ! colspan="7" align="center" | 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<ref>{{Cite journal |last1=Hendrickx |first1=C. |last2=Soto Núñez |first2=M. |last3=Araújo |first3=R. |last4=Meso |first4=J. G. |last5=Maganuco |first5=S. |last6=Ben-Salahuddin |first6=A. |year=2025 |title=Isolated abelisaurid teeth from Gondwana and dental evolution in Abelisauridae |url=https://www.ameghiniana.org.ar/index.php/ameghiniana/libraryFiles/downloadPublic/145 |journal=Ameghiniana |doi=10.5710/AMGH.17.09.2025.3654}}</ref> |The earliest record of Abelisauridae | |- | Theropoda indet. | Indeterminate | IIIb | | MSNM V6234 "a large, serrated tooth crown"<ref name=":4">'''Maganuco S, Cau A, Dal Sasso C, Pasini G.''' '''2007'''. [https://www.researchgate.net/publication/257651213_Evidence_of_large_theropods_from_the_Middle_Jurassic_of_the_Mahajanga_Basin_NW_Madagascar_with_implications_for_ceratosaurian_pedal_ungual_evolution 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</ref> MSNM V5804 vertebra, isolated teeth representing 8 morphotypes<ref>Maganuco S., Cau A. & Pasini G.. 2005 [https://www.researchgate.net/publication/257651210_First_description_of_theropod_remains_from_the_Middle_Jurassic_Bathonian_of_Madagascar 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.</ref> | | |- | Ceratosauria indet. | Indeterminate | IIIb | | MSNM V6235 Pedal ungual<ref name=":4" /> | | |- |}

=== Crocodyliformes === {| class="wikitable" align="center" |- ! colspan="7" align="center" | Crocodyliformes of the Isalo III Formation |- ! Genus ! Species ! Location ! Stratigraphic position ! Material ! Notes ! Images |- | ''Andrianavoay''<ref name=JohnsonMM>{{cite journal |author1=Michela M. Johnson |author2=Mark T. Young |author3=Stephen L. Brusatte |year=2020 |title=The phylogenetics of Teleosauroidea (Crocodylomorpha, Thalattosuchia) and implications for their ecology and evolution |journal=PeerJ |volume=8 |article-number=e9808 |doi=10.7717/peerj.9808 |pmid=33083104 |pmc=7548081 |doi-access=free }}</ref> | ''A. baroni'' | IIIb | | | A machimosaurine thelattosuchian | |- | ''Razanandrongobe''<ref name=":0">Dal Sasso et al., 2017</ref> | ''R. sakalavae'' | IIIb | | | A notosuchian | center|frameless |- |}

== See also == * List of dinosaur-bearing rock formations * List of fossiliferous stratigraphic units in Madagascar * Geology of Madagascar

== References == {{Reflist|3}}

=== Bibliography === <!--most recent first--> * {{cite journal |first1=Rafael |last1=Royo Torres |first2=Alberto |last2=Cobos |first3=Pedro |last3=Mocho |first4=Luis |last4=Alcalá |title=Origin and evolution of turiasaur dinosaurs set by means of a new 'rosetta' specimen from Spain |journal=Zoological Journal of the Linnean Society |year=2021 |volume=191 |issue= |pages= 201–227|doi=10.1093/zoolinnean/zlaa091|doi-access=free }} * {{cite journal |last1=Bindellini |first1=Gabriele |last2=Sasso |first2=Cristiano Dal |year=2019 |title=Sauropod teeth from the Middle Jurassic of Madagascar, and the oldest record of Titanosauriformes |journal=Papers in Palaeontology |volume=7 |pages= 137–161|doi=10.1002/spp2.1282|s2cid=203376597 }} * {{cite journal |last1=Dal Sasso |first1=Cristiano |last2=Pasini |first2=Giovanni |last3=Fleury |first3=Guillaume |last4=Maganuco |first4=Simone |year=2017 |title=''Razanandrongobe sakalavae'', a gigantic mesoeucrocodylian from the Middle Jurassic of Madagascar, is the oldest known notosuchian |journal=PeerJ |volume=5 |article-number=e3481|doi=10.7717/peerj.3481 |pmid=28690926 |pmc=5499610 |doi-access=free }} * {{cite journal |last1=Geiger |first1=Markus |last2=Clark |first2=David Norman |last3=Mette |first3=Wolfgang |year=2004 |title=Reappraisal of the timing of the breakup of Gondwana based on sedimentological and seismic evidence from the Morondava Basin, Madagascar |journal=Journal of African Earth Sciences |volume=38 |issue=4 |pages=363–381|doi=10.1016/j.jafrearsci.2004.02.003 |bibcode=2004JAfES..38..363G }} * {{cite book |editor-last1=Weishampel |editor-first1=David B. |editor-last2=Dodson |editor-first2=Peter |editor-last3=Osmólska |editor-first3=Halszka |year=2004 |title=The Dinosauria |edition=2nd |url=https://books.google.com/books?id=vtZFDb_iw40C |location=Berkeley |publisher=University of California Press |pages=1–880 |isbn=9780520941434}} * {{cite journal |last=Thevenin |first=A |year=1907 |title=Paléontologie de Madagascar. IV Dinosauriens |url=https://paleoglot.org/files/Thevenin_07.pdf |journal=Annales de Paléontologie |volume=2 |pages=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

Category:Geologic formations of Madagascar Category:Jurassic System of Africa Category:Middle Jurassic Africa Category:Jurassic Madagascar Category:Bajocian Stage Category:Bathonian Stage Category:Sandstone formations Category:Shale formations Category:Marl formations Category:Paleontology in Madagascar