{{Short description|Informal Triassic geological unit in Madagascar}} {{Infobox rockunit | name = Isalo II Formation | period = Carnian | age = [[Ladinian]]-[[Carnian]] | image = | imagesize = | caption = | type = [[Geological formation]] | prilithology = [[Sandstone]], [[mudstone]] | otherlithology = | unitof = [[Isalo Group]] | subunits = | underlies = [[Isalo III Formation]] ([[unconformity]]) | overlies = [[Isalo I Formation]] | thickness = | area = | map = {{Location map+ | Madagascar | relief = 1 | width = 160 | float = center | places = {{Location map~ | Madagascar | lat_deg = -20.3 | lon_deg = 45.4 | mark = Pink ff0080 pog.svg | marksize = 12 }} }} | map_caption = | location = | coordinates = {{coord|20.3|S|45.4|E|display=inline,title}} | paleocoordinates = {{coord|23.1|S|24.7|E|display=inline}} | region = [[Mahajanga Province|Mahajanga]] & [[Toliara Province]]s | country = [[Madagascar]] | extent = [[Morondava Basin]], [[Mahajanga Basin]] }} '''Isalo II''', also known as the '''Makay Formation''', is an informal [[Triassic]] geological unit in [[Madagascar]].<ref name="nesbitt2015">{{cite journal|last1=Nesbitt|first1=S.J.|last2=Flynn|first2=J.J.|last3=Pritchard|first3=A.C.|last4=Parrish|first4=M.J.|last5=Ranivoharimanana|first5=L.|last6=Wyss|first6=A.R.|year=2015|title=Postcranial osteology of ''Azendohsaurus madagaskarensis'' (?Middle to Upper Triassic, Isalo Group, Madagascar) and its systematic position among stem archosaur reptiles.|url=https://www.researchgate.net/publication/286412354|journal=Bulletin of the American Museum of Natural History|volume=398|pages=1–126|doi=10.1206/amnb-899-00-1-126.1|issn=0003-0090|hdl-access=free|hdl=2246/6624|s2cid=86289421}}</ref>
It is described as "thick beds of mottled red or green clays associated with soft cross-bedded sandstones, light in colour and much finer-grained than the Isalo I sandstones." It is prominent in the [[Makay Massif]].<ref>Brenon, P. (1972). The Geology of Madagascar. In: Battistini, R., Richard-Vindard, G. (eds) ''Biogeography and Ecology in Madagascar''. Monographiae Biologicae, vol 21. Springer, Dordrecht. https://doi.org/10.1007/978-94-015-7159-3_2</ref>
== Fossil content == === Amphibians === {| class="wikitable" align="center" |- ! colspan="3" align="center" | '''Amphibians''' |- ! Taxon ! Material ! Notes |- | [[Metoposauridae]] indet. | An [[interclavicle]], skull fragments, and intercentra | Indeterminate [[metoposaurid]] remains similar to those of [[India]]n metoposaurids. Some fossils were the basis for the dubious species "''[[Metoposaurus|Metoposaurus hoffmani]]''". May be from Isalo II or III.<ref name="Isalotemnos">{{Cite journal|last1=Fortuny|first1=Josep|last2=Arbez|first2=Thomas|last3=Mujal|first3=Eudald|last4=Steyer|first4=J. Sébastien|date=2019-01-02|title=Reappraisal of 'Metoposaurus hoffmani' Dutuit, 1978, and description of new temnospondyl specimens from the Middle–Late Triassic of Madagascar (Morondava Basin)|journal=Journal of Vertebrate Paleontology|volume=39|issue=1|article-number=e1576701|doi=10.1080/02724634.2019.1576701|bibcode=2019JVPal..39E6701F |s2cid=146075668|issn=0272-4634}}</ref> |- | [[Stereospondyli]] indet. | Interclavicles | Indeterminate [[stereospondyl]] remains. May be from Isalo II or III.<ref name="Isalotemnos"/> |- |}
=== Reptiles === {| class="wikitable" align="center" |- ! colspan="3" align="center" | '''Synapsids''' |- ! Taxon ! Material ! Notes |- | [[Archosauriformes]] sp. | Teeth, a coracoid, a centrum fragment, and cranial fragments | Various indeterminate fragments, some of which may belong to dinosaurs.<ref name="B06">{{Cite journal|last1=Burmeister|first1=Kurtis C.|last2=Flynn|first2=John J.|last3=Parrish|first3=J. Michael|last4=Wyss|first4=Andre R.|date=2006|title=Paleogeographic and biostratigraphic implications of new early Mesozoic vertebrates from Poamay, central Morondava Basin, Madagascar|url=https://books.google.com/books?id=ulvmCQAAQBAJ&pg=PA457|journal=New Mexico Museum of Natural History & Science Bulletin|volume=37|pages=457–475}}</ref> |- | ''[[Azendohsaurus madagaskarensis]]''<ref name="F99earlydinosaurs">{{Cite journal|last1=Flynn|first1=John J.|last2=Parrish|first2=J. Michael|last3=Rakotosamimanana|first3=Berthe|last4=Simpson|first4=William F.|last5=Whatley|first5=Robin L.|last6=Wyss|first6=André R.|date=1999-10-22|title=A Triassic Fauna from Madagascar, Including Early Dinosaurs|journal=Science|language=en|volume=286|issue=5440|pages=763–765|doi=10.1126/science.286.5440.763|jstor=2899382|issn=0036-8075|pmid=10531059}}</ref> | Numerous skulls and postcranial fossils<ref name="nesbitt2015"/> | An [[allokotosauria]]n [[archosauromorph]],<ref name="SVP08Azendoh">{{Cite journal|last1=Flynn|first1=John|last2=Nesbitt|first2=Sterling|last3=Parrish|first3=Michael|last4=Ranivoharimanana|first4=Lovasoa|last5=Wyss|first5=Andre|date=2008|title=A new species of basal archosauromorph from the Late Triassic of Madagascar|url=http://vertpaleo.org/Annual-Meeting/Future-Past-Meetings/MeetingPdfs/JVPabstracts2008.aspx#page=80|journal=Journal of Vertebrate Paleontology|volume=28|issue=sup3|pages=78A|archive-date=2019-12-06|access-date=2020-06-27|archive-url=https://web.archive.org/web/20191206154859/http://vertpaleo.org/Annual-Meeting/Future-Past-Meetings/MeetingPdfs/JVPabstracts2008.aspx#page=80|url-status=dead}}</ref><ref name="Azendoh2010">{{Cite journal|last1=Flynn|first1=John J.|last2=Nesbitt|first2=Sterling J.|last3=Parrish|first3=J. Michael|last4=Ranivoharimanana|first4=Lovasoa|last5=Wyss|first5=André R.|date=2010|title=A new species of ''Azendohsaurus'' (Diapsida: Archosauromorpha) from the Triassic Isalo Group of southwestern Madagascar: cranium and mandible|journal=Palaeontology|language=en|volume=53|issue=3|pages=669–688|doi=10.1111/j.1475-4983.2010.00954.x|bibcode=2010Palgy..53..669F |s2cid=82341339 |issn=1475-4983|doi-access=free}}</ref><ref name="nesbitt2015"/> originally mistakenly identified as a "prosauropod" dinosaur.<ref name="F99earlydinosaurs"/> |- | ''[[Isalorhynchus genovefae]]'' | Numerous fossils representing parts of the skull and postcrania | A [[rhynchosaur]] sometimes considered a species of ''[[Hyperodapedon]]''.<ref name="Isalorhynchus">{{Cite journal|last1=Langer|first1=Max|last2=Boniface|first2=Michael|last3=Cuny|first3=Gilles|last4=Barbieri|first4=Laurent|date=2000-04-01|title=The phylogenetic position of ''Isalorhynchus genovefae'', a Late Triassic rhynchosaur from Madagascar|url=http://www.paleolab.com.br/assets/uploads/files/pdf/Langer_et_al_2000a.pdf|journal=Annales de Paléontologie|language=en|volume=86|issue=2|pages=101–127|doi=10.1016/S0753-3969(00)80002-6|bibcode=2000AnPal..86..101L |issn=0753-3969}}</ref> Possibly represents two taxa.<ref name="Whatley99">{{Cite journal|last1=Whatley|first1=R.L.|last2=Flynn|first2=J.J.|last3=Parrish|first3=J.M.|last4=Simpson|first4=W.|last5=Wyss|first5=A.R.|date=1999|title=''Isalorhynchus'' revisited: two rhynchosaur skeletons from southwestern Madagascar|journal=Journal of Vertebrate Paleontology|volume=19|issue=sup3|pages=84A|jstor=4524027}}</ref> Reported [[sphenodontian]]<ref name="F99earlydinosaurs" /> fossils are most likely juvenile rhynchosaurs instead.<ref>{{Cite journal |last=Langer |first=Max Cardoso |date=2005 |title=Studies on continental Late Triassic tetrapod biochronology. II. The Ischigualastian and a Carnian global correlation |url=https://www.paleolab.com.br/assets/uploads/files/pdf/(005)%20Langer%202005b.pdf |journal=Journal of South American Earth Sciences |volume=19 |issue=2 |pages=219–239 |doi=10.1016/j.jsames.2005.04.002 |bibcode=2005JSAES..19..219L |issn=0895-9811}}</ref> |- | ''[[Kongonaphon kely]]''<ref>{{Cite journal|last1=Kammerer|first1=Christian F.|last2=Nesbitt|first2=Sterling J.|last3=Flynn|first3=John J.|last4=Ranivoharimanana|first4=Lovasoa|last5=Wyss|first5=André R.|date=2020-07-02|title=A tiny ornithodiran archosaur from the Triassic of Madagascar and the role of miniaturization in dinosaur and pterosaur ancestry|journal=Proceedings of the National Academy of Sciences|volume=117|issue=30|pages=17932–17936|language=en|doi=10.1073/pnas.1916631117|pmid=32631980|s2cid=220386589|issn=0027-8424|pmc=7395432|bibcode=2020PNAS..11717932K |doi-access=free }}</ref> | A maxilla and postcranial material | A tiny [[lagerpetid]] [[avemetatarsalia]]n<ref name="SVP19lagerpetid">{{Cite journal|last1=Kammerer|first1=Christian F.|last2=Nesbitt|first2=Sterling J.|last3=Flynn|first3=John J.|last4=Ranivoharimanana|first4=Lovasoa|last5=Wyss|first5=Andre|date=October 2019|title=A new lagerpetid archosaur from the Triassic of Madagascar and the importance of miniaturization in ornithodiran evolution|url=http://vertpaleo.org/Annual-Meeting/Annual-Meeting-Home/SVP-Program-book-v5_w-covers.aspx#page=128|journal=Society of Vertebrate Paleontology Abstracts of Papers, 79th Annual Meeting|page=127|access-date=2020-06-27|archive-date=2020-12-15|archive-url=https://web.archive.org/web/20201215024254/http://vertpaleo.org/Annual-Meeting/Annual-Meeting-Home/SVP-Program-book-v5_w-covers.aspx#page=128}}</ref> |- |''[[Mambachiton|Mambachiton fiandohana]]''<ref>{{Cite journal |last1=Nesbitt |first1=Sterling J. |last2=Patellos |first2=Emily |last3=Kammerer |first3=Christian F. |last4=Ranivoharimanana |first4=Lovasoa |last5=Wyss |first5=Andre´ R. |last6=Flynn |first6=John J. |date=25 July 2023 |title=The earliest-diverging avemetatarsalian: a new osteoderm-bearing taxon from the Triassic (?Earliest Late Triassic) of Madagascar and the composition of avemetatarsalian assemblages prior to the radiation of dinosaurs |journal=Zoological Journal of the Linnean Society |volume=199 |issue=zlad038 |pages=327–353 |doi=10.1093/zoolinnean/zlad038|doi-access=free }}</ref> |A partial skeleton |An armored [[basal (phylogenetics)|basal]] avemetatarsalian<ref name="SVP19armoredave">{{Cite journal |last1=Patellos |first1=Emily A. |last2=Nesbitt |first2=Sterling J. |last3=Kammerer |first3=Christian F. |last4=Wyss |first4=Andre |last5=Flynn |first5=John J. |last6=Ranivoharimanana |first6=Lovasoa |date=October 2019 |title=A new reptile from the ?Middle Triassic of Madagascar may represent the earliest-diverging Avemetatarsalia (Archosauria) |url=http://vertpaleo.org/Annual-Meeting/Annual-Meeting-Home/SVP-Program-book-v5_w-covers.aspx#page=168 |journal=Society of Vertebrate Paleontology Abstracts of Papers, 79th Annual Meeting |page=167 |archive-url=https://web.archive.org/web/20201215024254/http://vertpaleo.org/Annual-Meeting/Annual-Meeting-Home/SVP-Program-book-v5_w-covers.aspx#page=168 |archive-date=2020-12-15 |access-date=2020-06-27}}</ref> |- | [[Phytosauria]] indet. | Teeth | Similar to ''[[Rutiodon]]'' teeth.<ref name="B06"/> |- | [[Procolophonidae]] sp. | A jaw fragment and other remains | An unnamed [[procolophonid]] [[parareptile]]<ref name="Isalorhynchus"/> |- | [[Pseudosuchia]] indet. | Osteoderms | Likely referable to [[stagonolepid]] [[aetosaurs]], though similar to [[goniopholidid]] [[crocodylomorph]]s as well.<ref name="B06"/> |- | [[Silesauridae]] sp. | | An unnamed [[silesaurid]] [[dinosauromorph]]<ref name="SVP19armoredave"/> |- |}
=== Synapsids === {| class="wikitable" align="center" |- ! colspan="3" align="center" | '''Synapsids''' |- ! Taxon ! Material ! Notes |- | ''[[Chiniquodon kalanoro]]''<ref name="Chiniquodon2010">{{Cite journal|last1=Kammerer|first1=Christian F.|last2=Flynn|first2=John J.|last3=Ranivoharimanana|first3=Lovasoa|last4=Wyss|first4=André R.|date=2010-12-02|title=The first record of a probainognathian (Cynodontia: Chiniquodontidae) from the Triassic of Madagascar|journal=Journal of Vertebrate Paleontology|volume=30|issue=6|pages=1889–1894|doi=10.1080/02724634.2010.520784|jstor=25790814|bibcode=2010JVPal..30.1889K |s2cid=85868922|issn=0272-4634}}</ref> | Part of a jaw | A [[chiniquodontid]] [[cynodont]] |- | ''[[Dadadon isaloi]]''<ref name="cynodonts2000">{{Cite journal|last1=Flynn|first1=John J.|last2=Parrish|first2=J. Michael|last3=Rakotosamimanana|first3=Berthe|last4=Ranivoharimanana|first4=Lovasoa|last5=Simpson|first5=William F.|last6=Wyss|first6=André R.|date=2000-09-25|title=New Traversodontids (Synapsida: Eucynodontia) from the Triassic of Madagascar|journal=Journal of Vertebrate Paleontology|volume=20|issue=3|pages=422–427|doi=10.1671/0272-4634(2000)020[0422:NTSEFT]2.0.CO;2|s2cid=130041740 |issn=0272-4634}}</ref> | Several skulls and jaw fragments<ref name="Dadadon2011">{{Cite journal|last1=Ranivoharimanana|first1=Lovasoa|last2=Kammerer|first2=Christian F.|last3=Flynn|first3=John J.|last4=Wyss|first4=André R.|date=2011-11-01|title=New material of ''Dadadon isaloi'' (Cynodontia, Traversodontidae) from the Triassic of Madagascar|journal=Journal of Vertebrate Paleontology|volume=31|issue=6|pages=1292–1302|doi=10.1080/02724634.2011.618154|jstor=41407685|bibcode=2011JVPal..31.1292R |s2cid=220437281|issn=0272-4634}}</ref><ref name="Dadadon2012">{{Cite journal|last1=Kammerer|first1=Christian F.|last2=Flynn|first2=John J.|last3=Ranivoharimanana|first3=Lovasoa|last4=Wyss|first4=André R.|date=October 2012|title=Ontogeny in the Malagasy Traversodontid ''Dadadon isaloi'' and a Reconsideration of its Phylogenetic Relationships|journal=Fieldiana Life and Earth Sciences|volume=2012|issue=5|pages=112–125|doi=10.3158/2158-5520-5.1.112|s2cid=84651546|issn=2158-5520}}</ref> | A [[massetognathine]]<ref name="Dadadon2012"/> [[traversodontid]] cynodont |- | [[Kannemeyeriiformes]] sp. | | An unnamed [[kannemeyeriiform]] [[dicynodont]]<ref name="F99earlydinosaurs"/><ref name="Chiniquodon2010"/><ref name="nesbitt2015"/> |- | ''[[Menadon besairiei]]''<ref name="cynodonts2000"/> | Skulls, jaws, and postcranial material<ref name="Menadon08">{{Cite journal|last1=Kammerer|first1=Christian F.|last2=Flynn|first2=John J.|last3=Ranivoharimanana|first3=Lovasoa|last4=Wyss|first4=André R.|date=2008-06-12|title=New material of ''Menadon besairiei'' (Cynodontia: Traversodontidae) from the Triassic of Madagascar|journal=Journal of Vertebrate Paleontology|volume=28|issue=2|pages=445–462|doi=10.1671/0272-4634(2008)28[445:NMOMBC]2.0.CO;2|s2cid=140720709 |issn=0272-4634}}</ref> | A [[traversodontid]] cynodont |- |}
== References == {{reflist}}
[[Category:Geologic formations of Madagascar]] [[Category:Triassic System of Africa]] [[Category:Triassic Madagascar]] [[Category:Ladinian Stage]] [[Category:Carnian Stage]] [[Category:Sandstone formations]] [[Category:Mudstone formations]] [[Category:Paleontology in Madagascar]]