Maevarano Formation
Encyclopedia
The Maevarano Formation is an Upper Cretaceous sedimentary rock formation found in the Mahajanga Province
of northwestern Madagascar
. It is most likely Maastrichtian
in age, and records a seasonal, semiarid environment with river
s that had greatly varying discharges
. Notable animal fossil
s recovered include the theropod dinosaur
Majungasaurus
, the early bird
Vorona
, the flying dromaeosaur Rahonavis
, the titanosaur
ian sauropod Rapetosaurus
, and the giant frog
Beelzebufo
.
The Maevarano Formation is well-exposed in the Mahajanga Basin, in particular near the village of Berivotra near the northwestern coast of the island where its outcrop
s have been heavily dissected by erosion
. At the time it was being deposited, its latitude
was between 30°S and 25°S as Madagascar drifted northward after splitting from India
about 88 million years ago. It is composed of three smaller units or members
. The lowest is the Masorobe Member, which is usually reddish and is at least 80 meters thick (262 ft). Its rocks are mostly poorly-sorted
coarse-grained sandstone
s with some finer-grained beds. It is separated by an erosional disconformity from the next member, the Anembalemba Member. The lower portion of the Anembalemba Member is fine to coarse clay
-rich sandstone, whitish or light grey in color, with cross-bedding
. The upper portion of this member is made of poorly-sorted clay-rich sandstone, light olive-grey in color, that lacks cross-bedding. Most vertebrate
fossils come from the Anembalemba Member, especially from the upper portion. The Miadana Member, the third and uppermost member, is not always present, and is up to 25 meters thick (82 ft); in some places. Elsewhere, it is replaced by the marine
Berivotra Formation. The Miadana Member is made up of claystone
, siltstone
, and sandstone, lacks cross-bedding, and has several colors of rock. The Maevarano Formation as a whole is underlain by the Marovoay beds and capped by the Berivotra Formation.
The age of the Maevarano Formation has been debated; the Berivotra Formation, which is partially contemporaneous with the upper portions of the formation, shows that at least the upper part of the Maevarano is Maastrichtian in age. There is no evidence that it is Campanian
, despite previous reports to that effect. The Berivotra Formation appears to include near its top a magnetic reversal, interpreted as the shift from Chron
30N to Chron 29R, which occurred approximately 65.8 million years ago (about 300 000 years before the K–T boundary
and associated Cretaceous–Tertiary extinction event. This suggests that Maevarano organisms also lived shortly before (geologically speaking
) the extinction event.
military physician Dr. Félix Salètes and his staff officer Landillon in 1895, and fossils and geologic data were sent to paleontologist Charles Depéret
. He briefly described the formation and named two dinosaurs from the remains (Titanosaurus
madagascariensis and Megalosaurus
crenatissimus, now Majungasaurus). Similar collections were made throughout the 20th century, yielding mostly fragmentary fossils; one such specimen, a rough partial skull roof, became the holotype
of supposed pachycephalosaur (bonehead dinosaur) Majungatholus in 1979. (This specimen was later shown to be part of the skull ornamentation of a Majungasaurus.) Large scale expeditions (seven to date), under the banner of the Mahajanga Basin Project, began in 1993. These expeditions, conducted jointly by Stony Brook University and the University of Antananarivo
, have greatly expanded knowledge of this formation and the organisms that lived while it was being deposited.
alluvial plain
that over time was covered by a marine transgression
. Broad, shallow rivers flowed to the northwest from central highlands; evidence for debris flow
s suggests that the discharges of the rivers varied greatly, with periods of dilute water flow, and periods of rapid erosion dumping sediment
into the channels. Paleosol
s are reddish and include root
casts. The paleosols and other sedimentologic
evidence indicate well-drained floodplain
s with abundant vegetation adapted to a relatively dry climate, strongly season
al (rainy
and dry season
s) and at times semiarid (not unlike the present climate of the area).
Animals found in the formation include frog
s (including Beelzebufo ampinga), turtle
s, snake
s, lizard
s, at least seven species
of crocodyliforms
(including species of Mahajangasuchus
and Trematochampsa
), abelisaurid theropod Majungasaurus, noasaurid
Masiakosaurus, two types of titanosaurian sauropods (Rapetosaurus and an unnamed second form), and at least five species of birds or very bird-like dinosaurs, including Rahonavis. The 6 to 7 meter long (20 to 23 ft
) Majungasaurus was likely the apex predator
in the terrestrial environment. Crocodyliforms were very diverse and abundant.
remains. Possible indeterminate spinosaurid remains.
s known from the Maevarano Formation include the gondwanathere Lavanify miolaka, known from two teeth, two more teeth that may represent a second gondwanathere, the broken tooth UA 8699
, which as been interpreted both as metatheria
n and as eutheria
n, a multituberculate tooth fragment, and a yet undescribed mammal known from an articulated skeleton.
Mahajanga Province
Mahajanga is a former province of Madagascar with an area of 150,023 km². It had a population of 1,896,000 . Its capital was Mahajanga.Except for Fianarantsoa, Mahajanga Province bordered all of the country's other provinces:...
of northwestern Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
. It is most likely Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
in age, and records a seasonal, semiarid environment with river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
s that had greatly varying discharges
Discharge (hydrology)
In hydrology, discharge is the volume rate of water flow, including any suspended solids , dissolved chemical species and/or biologic material , which is transported through a given cross-sectional area...
. Notable animal fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s recovered include the theropod dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
Majungasaurus
Majungasaurus
Majungasaurus is a genus of abelisaurid theropod dinosaur that lived in Madagascar from 70 to 65.5 million years ago, at the end of the Cretaceous Period. Only one species has been identified...
, the early bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
Vorona
Vorona
Vorona is a monotypic genus of prehistoric birds. It was described from fossils found in a Maevarano Formation quarry near the village of Berivotra, Mahajanga Province, Madagascar. The age is Late Cretaceous, probably Campanian . V...
, the flying dromaeosaur Rahonavis
Rahonavis
Rahonavis is a genus of bird-like dinosaur from the Late Cretaceous of what is now northwestern Madagascar. It is known from a partial skeleton found in Maevarano Formation rocks at a quarry near Berivotra, Mahajanga Province...
, the titanosaur
Titanosaur
Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes...
ian sauropod Rapetosaurus
Rapetosaurus
Rapetosaurus is a genus of sauropod dinosaur that lived in Madagascar from 70 to 65 million years ago, at the end of the Cretaceous Period. Only one species Rapetosaurus is a genus of sauropod dinosaur that lived in Madagascar from 70 to 65 million years ago, at the end of the Cretaceous Period....
, and the giant frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
Beelzebufo
Beelzebufo
Beelzebufo ampinga was a particularly large species of prehistoric frog first identified in 2007. Common names assigned by the popular media include "Devil Frog", "Devil Toad", and "The Frog From Hell"...
.
Description
Outcrop
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...
s have been heavily dissected by erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
. At the time it was being deposited, its latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
was between 30°S and 25°S as Madagascar drifted northward after splitting from India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
about 88 million years ago. It is composed of three smaller units or members
Geologic unit
A geological unit is a volume of rock or ice of identifiable origin and age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features that characterize it....
. The lowest is the Masorobe Member, which is usually reddish and is at least 80 meters thick (262 ft). Its rocks are mostly poorly-sorted
Sorting (sediment)
Sorting indicates the distribution of grain size of sediments, either in unconsolidated deposits or in sedimentary rocks. Poorly sorted indicates that the sediment sizes are mixed ; whereas well sorted indicates that the sediment sizes are similar .The degree of sorting may also indicate the energy...
coarse-grained sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
s with some finer-grained beds. It is separated by an erosional disconformity from the next member, the Anembalemba Member. The lower portion of the Anembalemba Member is fine to coarse clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
-rich sandstone, whitish or light grey in color, with cross-bedding
Cross-bedding
In geology, the sedimentary structures known as cross-bedding refer to horizontal units that are internally composed of inclined layers. This is a case in geology in which the original depositional layering is tilted, and the tilting is not a result of post-depositional deformation...
. The upper portion of this member is made of poorly-sorted clay-rich sandstone, light olive-grey in color, that lacks cross-bedding. Most vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
fossils come from the Anembalemba Member, especially from the upper portion. The Miadana Member, the third and uppermost member, is not always present, and is up to 25 meters thick (82 ft); in some places. Elsewhere, it is replaced by the marine
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
Berivotra Formation. The Miadana Member is made up of claystone
Claystone
Claystone is a geological term used to describe a clastic sedimentary rock that is composed primarily of clay-sized particles ....
, siltstone
Siltstone
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...
, and sandstone, lacks cross-bedding, and has several colors of rock. The Maevarano Formation as a whole is underlain by the Marovoay beds and capped by the Berivotra Formation.
The age of the Maevarano Formation has been debated; the Berivotra Formation, which is partially contemporaneous with the upper portions of the formation, shows that at least the upper part of the Maevarano is Maastrichtian in age. There is no evidence that it is Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
, despite previous reports to that effect. The Berivotra Formation appears to include near its top a magnetic reversal, interpreted as the shift from Chron
Polarity chron
A Polarity Chron, or chron, is a term used in stratigraphy to name the time interval represented by a magnetostratigraphic polarity unit. It represents a certain time period in geologic history where the Earth's magnetic field was in a "normal" and "reversed" position. Chrons are numbered in order...
30N to Chron 29R, which occurred approximately 65.8 million years ago (about 300 000 years before the K–T boundary
K–T boundary
The K–T boundary is a geological signature, usually a thin band, dated to 65.5 ± 0.3 Ma ago. K is the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period...
and associated Cretaceous–Tertiary extinction event. This suggests that Maevarano organisms also lived shortly before (geologically speaking
Deep time
Deep time is the concept that the Geologic time scale is vast because the Earth is very old. The modern philosophical concept was developed in the 18th century by Scottish geologist James Hutton...
) the extinction event.
History of exploration
The Maevarano Formation was first explored by FrenchFrench people
The French are a nation that share a common French culture and speak the French language as a mother tongue. Historically, the French population are descended from peoples of Celtic, Latin and Germanic origin, and are today a mixture of several ethnic groups...
military physician Dr. Félix Salètes and his staff officer Landillon in 1895, and fossils and geologic data were sent to paleontologist Charles Depéret
Charles Depéret
Charles Jean Julien Depéret was a French geologist and paleontologist. He was a member of the French Academy of Sciences, the Société géologique de France and dean of the Science faculty of Lyon....
. He briefly described the formation and named two dinosaurs from the remains (Titanosaurus
Titanosaurus
Titanosaurus is a genus of sauropod dinosaur, first described by Lydekker in 1877. It is known from the Maastrichtian Lameta Formation of India...
madagascariensis and Megalosaurus
Megalosaurus
Megalosaurus is a genus of large meat-eating theropod dinosaurs of the Middle Jurassic period of Europe...
crenatissimus, now Majungasaurus). Similar collections were made throughout the 20th century, yielding mostly fragmentary fossils; one such specimen, a rough partial skull roof, became the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
of supposed pachycephalosaur (bonehead dinosaur) Majungatholus in 1979. (This specimen was later shown to be part of the skull ornamentation of a Majungasaurus.) Large scale expeditions (seven to date), under the banner of the Mahajanga Basin Project, began in 1993. These expeditions, conducted jointly by Stony Brook University and the University of Antananarivo
University of Antananarivo
University of Antananarivo is the primary public university of Madagascar, located in the capital Antananarivo.The school traces its founding to 16 December 1955 and the formation of the Institute for Advanced Studies in Antananarivo. It quickly established itself as the main center for higher...
, have greatly expanded knowledge of this formation and the organisms that lived while it was being deposited.
Paleoenvironment
The Maevarano Formation is interpreted as a low-reliefRelief
Relief is a sculptural technique. The term relief is from the Latin verb levo, to raise. To create a sculpture in relief is thus to give the impression that the sculpted material has been raised above the background plane...
alluvial plain
Alluvial plain
An alluvial plain is a relatively flat landform created by the deposition of sediment over a long period of time by one or more rivers coming from highland regions, from which alluvial soil forms...
that over time was covered by a marine transgression
Transgression (geology)
A marine transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in flooding. Transgressions can be caused either by the land sinking or the ocean basins filling with water...
. Broad, shallow rivers flowed to the northwest from central highlands; evidence for debris flow
Debris flow
A debris flow is a fast moving, liquefied landslide of unconsolidated, saturated debris that looks like flowing concrete. It is differentiated from a mudflow in terms of the viscosity and textural properties of the flow. Flows can carry material ranging in size from clay to boulders, and may...
s suggests that the discharges of the rivers varied greatly, with periods of dilute water flow, and periods of rapid erosion dumping sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
into the channels. Paleosol
Paleosol
In the geosciences, paleosol can have two meanings. The first meaning, common in geology and paleontology, refers to a former soil preserved by burial underneath either sediments or volcanic deposits , which in the case of older deposits have lithified into rock...
s are reddish and include root
Root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
casts. The paleosols and other sedimentologic
Sedimentology
Sedimentology encompasses the study of modern sediments such as sand, mud , and clay, and the processes that result in their deposition. Sedimentologists apply their understanding of modern processes to interpret geologic history through observations of sedimentary rocks and sedimentary...
evidence indicate well-drained floodplain
Floodplain
A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...
s with abundant vegetation adapted to a relatively dry climate, strongly season
Season
A season is a division of the year, marked by changes in weather, ecology, and hours of daylight.Seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earth's axis relative to the plane of revolution...
al (rainy
Wet season
The the wet season, or rainy season, is the time of year, covering one or more months, when most of the average annual rainfall in a region occurs. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the...
and dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...
s) and at times semiarid (not unlike the present climate of the area).
Vertebrate paleofauna
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s (including Beelzebufo ampinga), turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s, snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s, lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s, at least seven species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of crocodyliforms
Crocodylomorpha
The Crocodylomorpha are an important group of archosaurs that include the crocodilians and their extinct relatives.During Mesozoic and early Tertiary times the Crocodylomorpha were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. These were...
(including species of Mahajangasuchus
Mahajangasuchus
Mahajangasuchus is an extinct genus of crocodyliform which had blunt, conical teeth. The type species, M. insignis, lived during the Late Cretaceous; its fossils have been found in the Maevarano Formation in northern Madagascar.Sereno et al....
and Trematochampsa
Trematochampsa
Trematochampsa is an extinct genus of crocodyliform from the Late Cretaceous In Beceten Formation of Niger. The type species, T. taqueti, was described by Eric Buffetaut in 1974. A second species, T. oblita, was named from Madagascar in 1979...
), abelisaurid theropod Majungasaurus, noasaurid
Noasauridae
Noasaurids were a group of theropod dinosaurs from the Cretaceous Period . They were generally small in size...
Masiakosaurus, two types of titanosaurian sauropods (Rapetosaurus and an unnamed second form), and at least five species of birds or very bird-like dinosaurs, including Rahonavis. The 6 to 7 meter long (20 to 23 ft
Ft
Ft or ft. may mean:* Foot , a unit of distance or length* Hungarian forint, the currency of Hungary* Fair Trade, the principle to give a fair price when trading* Fort, a fortified place, especially in place names...
) Majungasaurus was likely the apex predator
Apex predator
Apex predators are predators that have no predators of their own, residing at the top of their food chain. Zoologists define predation as the killing and consumption of another organism...
in the terrestrial environment. Crocodyliforms were very diverse and abundant.
Amphibians
| Amphibian Amphibian Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods... s of the Maevarano Formation |
||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Beelzebufo Beelzebufo Beelzebufo ampinga was a particularly large species of prehistoric frog first identified in 2007. Common names assigned by the popular media include "Devil Frog", "Devil Toad", and "The Frog From Hell"... |
Beelzebufo ampinga |
A large frog Frog Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail... . |
 |
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Dinosaurs
Indeterminate Lithostrotia remains formerly attributed to the titanosauridae. Undescribed Lithostrotia form. Indeterminate EnantiornithesEnantiornithes
Enantiornithes is an extinct group of primitive birds. They were the most abundant and diverse avialans of the Mesozoic. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 50 species of Enantiornithines have been named, but some...
remains. Possible indeterminate spinosaurid remains.
| Dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s reported from the Maevarano Formation |
||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Majungasaurus Majungasaurus Majungasaurus is a genus of abelisaurid theropod dinosaur that lived in Madagascar from 70 to 65.5 million years ago, at the end of the Cretaceous Period. Only one species has been identified... |
M. crenatissimus |
"Partial mandible." |
An abelisaur Abelisaur Abelisaurs were a group of ceratosaurian dinosaurs which lived in the Southern hemisphere during the Cretaceous period. Some well-known dinosaurs of this group include Abelisaurus, Carnotaurus, and Majungasaurus. They are known for their small arms... . |
  |
||
Masiakasaurus Masiakasaurus Masiakasaurus was a small predatory theropod dinosaur from the Late Cretaceous of Madagascar. It was named in 2001 by Scott D. Sampson, Matthew Carrano, and Catherine A. Forster. Unlike most theropods, the front teeth of Masiakasaurus projected forward instead of straight down... |
M. knopfleri |
"Disarticulated remains of at least 6 individuals," as well as other isolated fossils. |
A noasaurid abelisaur. |
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Rahonavis Rahonavis Rahonavis is a genus of bird-like dinosaur from the Late Cretaceous of what is now northwestern Madagascar. It is known from a partial skeleton found in Maevarano Formation rocks at a quarry near Berivotra, Mahajanga Province... |
R. ostromi |
"Partial postcranial skeleton." |
A dromaeosaurid. |
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Rapetosaurus Rapetosaurus Rapetosaurus is a genus of sauropod dinosaur that lived in Madagascar from 70 to 65 million years ago, at the end of the Cretaceous Period. Only one species Rapetosaurus is a genus of sauropod dinosaur that lived in Madagascar from 70 to 65 million years ago, at the end of the Cretaceous Period.... |
Rapetosaurus krausei |
"[Three] skulls, at least [one] postcranial skeleton." |
A titanosaur Titanosaur Titanosaurs were a diverse group of sauropod dinosaurs, which included Saltasaurus and Isisaurus. It includes some of the heaviest creatures ever to walk the earth, such as Argentinosaurus and Paralititan — which some believe have weighed up to 100 tonnes... . |
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Stegosaurus Stegosaurus Stegosaurus is a genus of armored stegosaurid dinosaur. They lived during the Late Jurassic period , some 155 to 150 million years ago in what is now western North America. In 2006, a specimen of Stegosaurus was announced from Portugal, showing that they were present in Europe as well... |
S. madagascariensis |
"Teeth." |
Possible indeterminate ornithischian remains. |
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Titanosaurus Titanosaurus Titanosaurus is a genus of sauropod dinosaur, first described by Lydekker in 1877. It is known from the Maastrichtian Lameta Formation of India... |
T. madagascariensis |
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Vorona Vorona Vorona is a monotypic genus of prehistoric birds. It was described from fossils found in a Maevarano Formation quarry near the village of Berivotra, Mahajanga Province, Madagascar. The age is Late Cretaceous, probably Campanian . V... |
V. berivotrensis |
"Partial hindlimbs." |
An ornithuromorph. |
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Crocodylomorphs
| Crocodylomorphs of the Maevarano Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Mahajangasuchus Mahajangasuchus Mahajangasuchus is an extinct genus of crocodyliform which had blunt, conical teeth. The type species, M. insignis, lived during the Late Cretaceous; its fossils have been found in the Maevarano Formation in northern Madagascar.Sereno et al.... |
M. insignis |
A peirosaurid. |
  |
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Miadanasuchus Miadanasuchus Miadanasuchus is an extinct genus of trematochampsid which existed in Maevarano Formation of Madagascar during the late Cretaceous period . It was first named by Erin L. Rasmusson Simons and Gregory A. Buckley in 2009 and the type species is Miadanasuchus oblita.... |
M. oblita |
Formerly known as Trematochampsa oblita. |
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Simosuchus Simosuchus Simosuchus is an extinct genus of notosuchian crocodylomorphs from the Late Cretaceous of Madagascar. It is named for its unusually short skull. Fully grown individuals were about in length. The type species is S. clarki, found from the Maevarano Formation in Mahajanga Province.The teeth of S... |
S. clarki |
A chimaerasuchid. |
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Trematochampsa Trematochampsa Trematochampsa is an extinct genus of crocodyliform from the Late Cretaceous In Beceten Formation of Niger. The type species, T. taqueti, was described by Eric Buffetaut in 1974. A second species, T. oblita, was named from Madagascar in 1979... |
T. oblita |
A trematochampsid Trematochampsidae Trematochampsidae is an extinct family of mesoeucrocodylian crocodylomorph. Fossils are present from Madagascar, Morocco, Niger, Argentina, and Brazil... . Later referred to Miadanasuchus oblita Miadanasuchus Miadanasuchus is an extinct genus of trematochampsid which existed in Maevarano Formation of Madagascar during the late Cretaceous period . It was first named by Erin L. Rasmusson Simons and Gregory A. Buckley in 2009 and the type species is Miadanasuchus oblita.... |
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Araripesuchus Araripesuchus Araripesuchus is a genus of extinct crocodyliform whose species existed during the Cretaceous period of the late Mesozoic era some 125 to 65 million years ago. They are generally considered to be notosuchians , characterized by their varied teeth types and distinct skull elements... |
A. tsangatsangana |
A notosuchia Notosuchia Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Cretaceous. Fossils have been found from South America, Africa, and Asia... n. |
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Mammals
MammalMammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s known from the Maevarano Formation include the gondwanathere Lavanify miolaka, known from two teeth, two more teeth that may represent a second gondwanathere, the broken tooth UA 8699
UA 8699
UA 8699 is a fossil mammalian tooth from the Cretaceous of Madagascar. A broken lower molar about 3.5 mm long, it is from the Maastrichtian of the Maevarano Formation in northwestern Madagascar...
, which as been interpreted both as metatheria
Metatheria
Metatheria is a grouping within the animal class Mammalia. First proposed by Thomas Henry Huxley in 1880, it is nearly synonymous with the earlier taxon Marsupialia though it is slightly wider since it also contains the nearest fossil relatives of marsupial mammals.The earliest known...
n and as eutheria
Eutheria
Eutheria is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals than to living marsupials . They are distinguished from noneutherians by various features of the feet, ankles, jaws and teeth...
n, a multituberculate tooth fragment, and a yet undescribed mammal known from an articulated skeleton.