Isalo II

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Isalo II Formation
Stratigraphic range: Ladinian-Carnian
Type Geological formation
Unit of Isalo Group
Underlies Isalo III Formation (unconformity)
Overlies Isalo I Formation
Lithology
Primary Sandstone, mudstone
Location
Coordinates 20°18′S45°24′E / 20.3°S 45.4°E / -20.3; 45.4
Approximate paleocoordinates 23°06′S24°42′E / 23.1°S 24.7°E / -23.1; 24.7
Region Mahajanga & Toliara Provinces
CountryFlag of Madagascar.svg  Madagascar
Extent Morondava Basin, Mahajanga Basin
Madagascar physical map.svg
Pink ff0080 pog.svg
Isalo II (Madagascar)

Isalo II, also known as the Makay Formation, is an informal Triassic geological unit in Madagascar. [1]

Contents

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. [2]

Fossil content

Amphibians

Amphibians
TaxonMaterialNotes
Metoposauridae indet.An interclavicle, skull fragments, and intercentraIndeterminate metoposaurid remains similar to those of Indian metoposaurids. Some fossils were the basis for the dubious species " Metoposaurus hoffmani ". May be from Isalo II or III. [3]
Stereospondyli indet.InterclaviclesIndeterminate stereospondyl remains. May be from Isalo II or III. [3]

Reptiles

Synapsids
TaxonMaterialNotes
Archosauriformes sp.Teeth, a coracoid, a centrum fragment, and cranial fragmentsVarious indeterminate fragments, some of which may belong to dinosaurs. [4]
Azendohsaurus madagaskarensis [5] Numerous skulls and postcranial fossils [1] An allokotosaurian archosauromorph, [6] [7] [1] originally mistakenly identified as a "prosauropod" dinosaur. [5]
Isalorhynchus genovefae Numerous fossils representing parts of the skull and postcraniaA rhynchosaur sometimes considered a species of Hyperodapedon . [8] Possibly represents two taxa. [9] Reported sphenodontian [5] fossils are most likely juvenile rhynchosaurs instead. [10]
Kongonaphon kely [11] A maxilla and postcranial materialA tiny lagerpetid avemetatarsalian [12]
Mambachiton fiandohana [13] A partial skeletonAn armored basal avemetatarsalian [14]
Phytosauria indet.TeethSimilar to Rutiodon teeth. [4]
Procolophonidae sp.A jaw fragment and other remainsAn unnamed procolophonid parareptile [8]
Pseudosuchia indet.OsteodermsLikely referable to stagonolepid aetosaurs, though similar to goniopholidid crocodylomorphs as well. [4]
Silesauridae sp.An unnamed silesaurid dinosauromorph [14]

Synapsids

Synapsids
TaxonMaterialNotes
Chiniquodon kalanoro [15] Part of a jawA chiniquodontid cynodont
Dadadon isaloi [16] Several skulls and jaw fragments [17] [18] A massetognathine [18] traversodontid cynodont
Kannemeyeriiformes sp.An unnamed kannemeyeriiform dicynodont [5] [15] [1]
Menadon besairiei [16] Skulls, jaws, and postcranial material [19] A traversodontid cynodont

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Azendohsauridae is a family of allokotosaurian archosauromorphs that lived during the Middle to Late Triassic period, around 242-216 million years ago. The family was originally named solely for the eponymous Azendohsaurus, marking out its distinctiveness from other allokotosaurs, but as of 2022 the family now includes four other genera: the basal genus Pamelaria, the large horned herbivore Shringasaurus, and two carnivorous genera grouped into the subfamily-level subclade Malerisaurinae, Malerisaurus and Puercosuchus, and potentially also the dubious genus Otischalkia. Most fossils of azendohsaurids have a Gondwanan distribution, with multiple species known across Morocco and Madagascar in Africa as well as India, although fossils of malerisaurine azendohsaurids have also been found in the southwestern United States of North America.

<i>Kongonaphon</i> Extinct genus of reptiles

Kongonaphon is an extinct genus of lagerpetid avemetatarsalians from the Middle to Late Triassic of Madagascar. It contains a single species, Kongonaphon kely, which is known from a fragmentary partial skeleton. This fossil hails from the late Ladinian or early Carnian-age "basal Isalo II beds". As the first lagerpetid found in Africa, Kongonaphon extends the range of the family significantly. It possessed a combination of features from various other lagerpetids, but developed particularly long and slender leg bones. Kongonaphon is also the first lagerpetid for which fossils of the snout and teeth are known. It was likely an insectivore based on the shape and texture of its teeth.

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References

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