''Hovasaurus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

diapsid Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The group first appeared about three hundred million years ago ...

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

belonging to the order

Eosuchia Eosuchians are an extinct order of diapsid reptiles. Depending on which taxa are included the order may have ranged from the late Carboniferous to the Eocene but the consensus is that eosuchians are confined to the Permian and Triassic. Eosuch ...

. It lived in what is now

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

during the

Late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

and

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...

, being a survivor of the

Permian–Triassic extinction event The Permian–Triassic (P–T, P–Tr) extinction event, also known as the Latest Permian extinction event, the End-Permian Extinction and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as ...

and the paleontologically youngest member of the

Tangasauridae Tangasauridae is a family of diapsids. Specimens have been found that are of Late Permian to Early Triassic in age from the Sakamena Group of western Madagascar. They lived alongside other taxa present from the Sakamena Group, including temnosp ...

. Fossils have been found in the Permian

Lower Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eight ...

and Triassic

Middle Sakamena Formation Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ...

s of the

Sakamena Group Sakamena is a village near Betroka in the region of Anosy in Madagascar. Sakamena is also the name of a Permian sedimentary geological formation that has yielded many vertebrate fossil, including Triadobatrachus (the first lissamphibian), Claudio ...

, where it is amongst the commonest fossils. Its morphology suggests an aquatic ecology.

Description

''Hovasaurus'' resembled a slender lizard, two thirds of total length was taken up by its long tail. It had snout-vent length up to long, with long tail. It was well adapted to an aquatic life, with the tail being laterally flattened like that of a

sea snake Sea snakes, or coral reef snakes, are elapid snakes that inhabit marine environments for most or all of their lives. They belong to two subfamilies, Hydrophiinae and Laticaudinae. Hydrophiinae also includes Australasian terrestrial snakes, wher ...

. Some stones have been found in the abdomen of fossil ''Hovasaurus'', indicating the creatures swallowed these for

ballast Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship, ...

, preventing them from floating to the surface when hunting fish.

Paleoenvironment

The Lower Sakamamena Formation was deposited in a wetland environment situated within a North-South orientated

rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear dep ...

, perhaps similar to

Lake Tanganyika Lake Tanganyika () is an African Great Lake. It is the second-oldest freshwater lake in the world, the second-largest by volume, and the second-deepest, in all cases after Lake Baikal in Siberia. It is the world's longest freshwater lake. ...

. The climate at the time of deposition was temperate, warm, and humid, with seasonal rainfall and possible monsoons Flora from the formation includes the equisetalean '' Schizoneura'', ''

Glossopteris ''Glossopteris'' tymology: from Ancient Greek γλῶσσα (glôssa, " tongue ") + πτερίς (pterís, " fern ")is the largest and best-known genus of the extinct Permian order of seed ferns known as Glossopteridales (also known as Arberia ...

'', and seed fern ''

Lepidopteris ''Lepidopteris'' ("scaly fern") is a form genus for leaves of Late Permian to Late Triassic Period Pteridospermatophyta, or seed ferns, which lived from around 260 to 200 million years ago in what is now Australia, Antarctica, India, South Amer ...

.'' Other vertebrates known from the Lower Sakamena Formation include the

palaeoniscoid Palaeoniscidae is an extinct family of ray-finned fishes (Actinopterygii) ascribed to the order Palaeonisciformes. The family includes the genus '' Palaeoniscum'' and potentially other Palaeozoic and Mesozoic early actinopterygian genera. The n ...

fish '' Atherstonia'', the

procolophonid Procolophonidae is an extinct family of small, lizard-like parareptiles known from the Late Permian to Late Triassic that were distributed across Pangaea, having been reported from Europe, North America, China, South Africa, South America, Antarc ...

parareptile ''

Barasaurus ''Barasaurus'' is an extinct genus of owenettid procolophonoid parareptile known from the late Late Permian and early Early Triassic of Madagascar. It contains a single species, ''Barasaurus besairiei''. Discovery ''Barasaurus besairiei'', the t ...

'', the gliding weigeltisaurid reptile ''

Coelurosauravus ''Coelurosauravus'' (meaning "hollow lizard grandfather") is a genus of basal diapsid reptiles, known from the Late Permian of Madagascar. Like other members of the family Weigeltisauridae, members of this genus possessed long, rod-like ossifica ...

'', neodiapsids ''

Claudiosaurus ''Claudiosaurus'' (''claudus'' is Latin for 'lameness' and ''saurus'' means 'lizard') is an extinct genus of diapsid reptiles from the Permian Sakamena Formation of the Morondava Basin, Madagascar. The pattern of the vertebrate, girle, and limbs ...

Thadeosaurus ''Thadeosaurus'' is an extinct genus of diapsid reptile belonging to the family Younginidae. Fossils have been found in the Lower Sakamena Formation (Sakamena Group) of the Morondava Basin, Madagascar in 1981, and date to the late Permian to the ...

'', and '' Acerodontosaurus'', fragments of rhinesuchid

temnospondyls Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carb ...

, an indeteriminate

theriodont The theriodonts (clade Theriodontia) are a major group of therapsids which appeared during the Middle Permian and which includes the gorgonopsians and the eutheriodonts, itself including the therocephalians and the cynodonts. Naming In 1876, Rich ...

therapsid Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more ...

and the

dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typicall ...

Oudenodon ''Oudenodon'' is an extinct genus of dicynodont. It was common throughout southern Africa during the Late Permian. Several species of ''Oudenodon'' are known. Both ''O. bainii'', the type species, and ''O. grandis'' are known from South Africa ...

.''Smith, R. M. H. 2000. Sedimentology and taphonomy of Late Permian vertebrate fossil localities in Southwestern Madagascar. Paleontologia Africana 36:25–41

Description

Paleoenvironment

References

Further reading