Isalo II Formation | |
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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 |
Approximate paleocoordinates | 23°06′S24°42′E / 23.1°S 24.7°E |
Region | Mahajanga & Toliara Provinces |
Country | Madagascar |
Extent | Morondava Basin, Mahajanga Basin |
Isalo II, also known as the Makay Formation, is an informal Triassic geological unit in Madagascar. [1]
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]
Amphibians | ||
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Taxon | Material | Notes |
Metoposauridae indet. | An interclavicle, skull fragments, and intercentra | Indeterminate 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. | Interclavicles | Indeterminate stereospondyl remains. May be from Isalo II or III. [3] |
Synapsids | ||
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Taxon | Material | Notes |
Archosauriformes sp. | Teeth, a coracoid, a centrum fragment, and cranial fragments | Various 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 postcrania | A 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 material | A tiny lagerpetid avemetatarsalian [12] |
Mambachiton fiandohana [13] | A partial skeleton | An armored basal avemetatarsalian [14] |
Phytosauria indet. | Teeth | Similar to Rutiodon teeth. [4] |
Procolophonidae sp. | A jaw fragment and other remains | An unnamed procolophonid parareptile [8] |
Pseudosuchia indet. | Osteoderms | Likely referable to stagonolepid aetosaurs, though similar to goniopholidid crocodylomorphs as well. [4] |
Silesauridae sp. | An unnamed silesaurid dinosauromorph [14] | |
Synapsids | ||
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Taxon | Material | Notes |
Chiniquodon kalanoro [15] | Part of a jaw | A 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 |
Chiniquodon is an extinct genus of carnivorous cynodonts, which lived during the Late Triassic (Carnian) in South America and Africa. Chiniquodon was closely related to the genus Aleodon, and close to the ancestry of mammals.
Azendohsaurus is an extinct genus of herbivorous archosauromorph reptile from roughly the late Middle to early Late Triassic Period of Morocco and Madagascar. The type species, Azendohsaurus laaroussii, was described and named by Jean-Michel Dutuit in 1972 based on partial jaw fragments and some teeth from Morocco. A second species from Madagascar, A. madagaskarensis, was first described in 2010 by John J. Flynn and colleagues from a multitude of specimens representing almost the entire skeleton. The generic name "Azendoh lizard" is for the village of Azendoh, a local village near where it was first discovered in the Atlas Mountains. It was a bulky quadruped that unlike other early archosauromorphs had a relatively short tail and robust limbs that were held in an odd mix of sprawled hind limbs and raised forelimbs. It had a long neck and a proportionately small head with remarkably sauropod-like jaws and teeth.
Trilophosaurs are lizard-like Triassic allokotosaur reptiles related to the archosaurs. The best known genus is Trilophosaurus, a herbivore up to 2.5 metres long. It had a short, unusually heavily built skull, equipped with massive, broad flattened cheek teeth with sharp shearing surfaces for cutting up tough plant material. Teeth are absent from the premaxilla and front of the lower jaw, which in life were probably equipped with a horny beak.
Avemetatarsalia is a clade of diapsid reptiles containing all archosaurs more closely related to birds than to crocodilians. The two most successful groups of avemetatarsalians were the dinosaurs and pterosaurs. Dinosaurs were the largest terrestrial animals for much of the Mesozoic Era, and one group of small feathered dinosaurs has survived up to the present day. Pterosaurs were the first flying vertebrates and persisted through the Mesozoic before dying out at the Cretaceous-Paleogene (K-Pg) extinction event. Both dinosaurs and pterosaurs appeared in the Triassic Period, shortly after avemetatarsalians as a whole. The name Avemetatarsalia was first established by British palaeontologist Michael Benton in 1999. An alternate name is Pan-Aves, or "all birds", in reference to its definition containing all animals, living or extinct, which are more closely related to birds than to crocodilians.
The Tecovas Formation is a geological formation in the Texas panhandle and eastern New Mexico. It is one of several formations encompassed by the Late Triassic Dockum Group.
Sterling Nesbitt is an American paleontologist best known for his work on the origin and early evolutionary patterns of archosaurs. He is currently an associate professor at Virginia Tech in the Department of Geosciences.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 2010.
Dadadon is an extinct genus of traversodontid cynodonts which existed in Madagascar during the late Middle Triassic. The only species in the genus is Dadadon isaloi.
Menadon is an extinct genus of traversodontid cynodonts. The type and only species is Menadon besairiei.
Lagerpetidae is a family of basal avemetatarsalians. Though traditionally considered the earliest-diverging dinosauromorphs, fossils described in 2020 suggest that lagerpetids may instead be pterosauromorphs. Lagerpetid fossils are known from the Triassic of Argentina, Arizona, Brazil, Madagascar, New Mexico, and Texas. They were typically small, although some lagerpetids, like Dromomeron gigas and a specimen from the Santa Rosa Formation attributed to Dromomeron sp., were able to get quite large. Lagerpetid fossils are rare; the most common finds are bones of the hindlimbs, which possessed a number of unique features.
Christian Alfred Sidor is an American vertebrate paleontologist. He is currently a Professor in the Department of Biology, University of Washington in Seattle, as well as Curator of Vertebrate Paleontology and Associate Director for Research and Collections at the Burke Museum of Natural History and Culture. His research focuses on Permian and Triassic tetrapod evolution, especially on therapsids.
Gomphodontosuchinae is a subfamily of Triassic traversodontid cynodonts. It includes the genera Gomphodontosuchus, Exaeretodon, Santagnathus, Siriusgnathus, Menadon, Proexaeretodon,Protuberum, Ruberodon and Scalenodontoides.
Protorosauria is an extinct, likely paraphyletic group of basal archosauromorph reptiles from the latest Middle Permian to the end of the Late Triassic of Asia, Europe and North America. It was named by the English anatomist and paleontologist Thomas Henry Huxley in 1871 as an order, originally to solely contain Protorosaurus. Other names which were once considered equivalent to Protorosauria include Prolacertiformes and Prolacertilia.
Massetognathinae is an extinct subfamily of cynodonts in the family Traversodontidae. It includes four species from the Middle and Late Triassic: Massetognathus pascuali from Argentina, Massetognathus ochagaviae and Santacruzodon hopsoni from southern Brazil, and Dadadon isaloi from Madagascar. Massetognathines have several distinguishing characteristics, including flattened skulls, small canine teeth, and postcanine teeth with three cusps on their outer edges. Massetgognathinae was defined by Kammerer et al. (2012) as the clade containing all traversodontids more closely related to Massetognathus pascuali than to Gomphodontosuchus brasiliensis, and is the sister taxon of the traversodontid subfamily Gomphodontosuchinae, which was defined by Kammerer et al. (2008) as all traverodontids more closely related to G. brasiliensis than to M. pascuali.
Epipophyses are bony projections of the cervical vertebrae found in archosauromorphs, particularly dinosaurs. These paired processes sit above the postzygapophyses on the rear of the vertebral neural arch. Their morphology is variable and ranges from small, simple, hill-like elevations to large, complex, winglike projections. Epipophyses provided large attachment areas for several neck muscles; large epipophyses are therefore indicative of a strong neck musculature.
The Yerrapalli Formation is a Triassic rock formation consisting primarily of mudstones that outcrops in the Pranhita–Godavari Basin in southeastern India. The Yerrapalli Formation preserves fossils of freshwater and terrestrial vertebrates as well as trace fossils of invertebrates. The tetrapod fauna includes temnospondyl amphibians, archosauromorph reptiles, and dicynodonts.
Allokotosauria is a clade of early archosauromorph reptiles from the Middle to Late Triassic known from Asia, Africa, North America and Europe. Allokotosauria was first described and named when a new monophyletic grouping of specialized herbivorous archosauromorphs was recovered by Sterling J. Nesbitt, John J. Flynn, Adam C. Pritchard, J. Michael Parrish, Lovasoa Ranivoharimanana and André R. Wyss in 2015. The name Allokotosauria is derived from Greek meaning "strange reptiles" in reference to unexpected grouping of early archosauromorph with a high disparity of features typically associated with herbivory.
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.
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.
Mambachiton is an extinct genus of basal avemetatarsalian from the Middle/Upper Triassic Makay Formation of Madagascar. The genus contains a single species, M. fiandohana, known from a partial skeleton with articulated osteoderms.