''Coelurosauravus'' (meaning "hollow lizard grandfather") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of basal

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 a ...

reptiles 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 rhynchoceph ...

, known from 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, ...

of Madagascar. Like other members of the family Weigeltisauridae, members of this genus possessed long, rod-like ossifications projecting outwards from the body. These bony rods were not extensions of the ribs but were instead newly developed bones derived from the skin of the animal, a feature unique to weigeltisaurids. It is believed that during life, these structures formed folding wings used for

gliding flight Gliding flight is heavier-than-air flight without the use of thrust; the term volplaning also refers to this mode of flight in animals. It is employed by gliding animals and by aircraft such as gliders. This mode of flight involves flying a s ...

, similar to living gliding ''

Draco Draco is the Latin word for serpent or dragon. Draco or Drako may also refer to: People * Draco (lawgiver) (from Greek: Δράκων; 7th century BC), the first lawgiver of ancient Athens, Greece, from whom the term ''draconian'' is derived * ...

'' lizards. ''Coelurosauravus'' is solely known from the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specim ...

, ''C. elivensis'', which was named by Jean Piveteau in 1926 based on fossils from the Lower Sakamena Formation of

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 Afric ...

. The species '' Weigeltisaurus jaekeli'' from Europe was formerly considered a species of ''Coelurosauravus'', but is now considered distinct.

History of discovery

The only known specimens of ''Coelurosauravus'' were collected in 1907-1908 by J.-M. Colcanap, a captain of the French colonial infantry, in southwest Madagascar. The precise location is not known, but it is likely from Mount Eliva near the upstream part of the Sakamena River, a tributary of the

Onilahy River Onilahy is a river in Atsimo-Andrefana and Anosy (Toliara Province), southern Madagascar. It flows down from the hills near Betroka to the Mozambique Channel. It empties at St. Augustin (), and into the Bay of Saint-Augustin. Two species of cich ...

. In 1926, the specimens were described by Jean Piveteau as ''Coelurosauravus'' ''elivensis''. In 1930 '' Weigeltisaurus jaekeli'' was described from specimens

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...

. This European species is now known from numerous specimens found in Germany (and one in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

), of which some were very well preserved. In 1987, ''Weigeltisaurus jaekeli'' was synonymized with ''Coelurosauravus'' as a second species, ''Coelurosauravus jaekeli''. However, a 2015 study reinstated ''Weigeltisaurus'' as a separate genus for ''"Coelurosauravus" jaekeli,'' which has been retained by subsequent authors''.'' In 1979 Robert L. Carroll placed one of the ''C. elivensis'' specimens into the new genus and species ''Daedalosaurus madigascariensis'', based on supposed differences with the holotype specimen, but it has subsequently been regarded as not distinct from ''C. elivensis.''

List of specimens

*IP 1908-11-21a: Holotype of ''C. elivensis'' (Piveteau, 1926). A poorly preserved skull and partial skeleton. * IP 1908-11-22a: A part and counterpart (IP 1908-11-23a) containing skull fragments and the anterior half of a skeleton. * IP 1908-5-2: Holotype of ''Daedalosaurus madagascariensis'' (Carroll, 1978). A part and counterpart (IP 1908-5-2b) of a partial skeleton including skull pieces and gliding structures.

Description

The skull of ''Coelurosauravus'' is the smallest of the weigeltisaurids, with a mature skull length of 3.5 cm around half those of other weigeltisaurids. The total combined head and torso length is , reaching a length of at least including the preserved length of the tail. Like other weigeltisaurids, the skull bones are covered in cranial ornamentation, consisting of low tubercles and spikes, including a horned frill present on the

squamosal bone The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral c ...

. In contrast to ''Weigeltisaurus'', only tubercles, rather than spikes, are present on the

parietal bone The parietal bones () are two bones in the skull which, when joined at a fibrous joint, form the sides and roof of the cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is n ...

, which is also shared with ''

Glaurung J. R. R. Tolkien's Middle-earth legendarium features dragons based on those of European legend, but going beyond them in having personalities of their own, such as the wily Smaug, who has features of both Fafnir and the ''Beowulf'' dragon. ...

''. The teeth are simple and conical in shape and packed into a dense row. The teeth sequentially decrease in size posteriorly. Compared to ''Weigeltisaurus'', ''Coelourosauravus'' has a shorter neck and longer thorax (which is also flattened), and like other weigeltisaurids the tail is elongate. Like other weigeltisaurdis, the penultimate

phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

are elongated, which in combination with their recurved unguals indicative of

claws A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...

were likely an adaption to cling to tree bark. Approximately 29 pairs of long, rod-shaped bones project from the sides of the body, these are proposed to represent modified gastralia or a novel dermal ossification.

Paleobiology

Though no stomach contents have been found, ''Coelurosauravus'' and other weigeltisaurds have been interpreted as

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...

insectivores. The simple conical teeth of ''Coelurosauravus'' are well adapted to the piercing of arthropod cuticle. The cranial ornamentation may have served a display purpose.

Gliding

The rods originate from the lower-lateral surface of the body. The furling and unfurling of the gliding membrane were likely controlled by the

abdominal muscles The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

. Preserved fossils of ''Weigeltisaurus'' show that the bony rods had a high degree of flexiiblity, similar to the ribs of living gliding lizards. Due to the low-wing configuration, it is likely that the gliding surface was angled upwards to increase stability. In living gliding lizards, it has been found that the forelimbs grab hold of the membrane during flight, suggesting that the forelimbs are used to control the patagium while in flight. Similar behaviour has been proposed for weigeltisaurids. This is supported the presence of an additional phalange in the fourth digit of the hands of weigeltisaurids, which would have allowed them to more effectively grasp the wing. In a 2011 study comparing ''Coelurosauravus elivensis'' and other extinct gliding reptiles to modern ''Draco'' species, ''Coelurosauravus'' was found to be a less efficient glider than modern ''Draco'' due to its larger body size, with a

wing loading In aerodynamics, wing loading is the total mass of an aircraft or flying animal divided by the area of its wing. The stalling speed of an aircraft in straight, level flight is partly determined by its wing loading. An aircraft or animal with a ...

around 107.9 N/m², 4.5 times than higher than ''Draco,'' with a substantial drop in height per glide, corresponding with a steep descent angle of more than 45 degrees. However, some authors have considered that the unique configuration and aspect ratio of the wings of weigeltisaurids means that the comparison needs to be tested experimentally.

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 d ...

, 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. T ...

. 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'', the

glossopterid Glossopteridales is an extinct order of plants belonging to Pteridospermatophyta, or seed ferns, also known as Arberiales and Ottokariales. They arose at the beginning of the Permian () on the southern continent of Gondwana, but became extinct a ...

gymnosperm ''

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 na ...

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 ...

'', the neodiapsids ''

Hovasaurus ''Hovasaurus'' is an extinct genus of diapsid reptile belonging to the order Eosuchia. It lived in what is now Madagascar during the Late Permian and Early Triassic, being a survivor of the Permian–Triassic extinction event and the paleontolog ...

, Claudiosaurus, Thadeosaurus'', and '' Acerodontosaurus'', fragments of rhinesuchid temnospondyls, an indeterminate theriodont

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, typic ...

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

History of discovery

List of specimens

Description

Paleobiology

Gliding

Paleoenvironment

See also

References

Further reading