''Coelurosauravus'' (meaning "hollow-tailed lizard grandfather") is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of gliding reptile, known from the

Late Permian Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudonym used by Dave Groh ...

of Madagascar. Like other members of the family

Weigeltisauridae Weigeltisauridae is a family of gliding neodiapsid reptiles that lived during the Late Permian, between 259.51 and 251.9 million years ago. Fossils of weigeltisaurids have been found in Madagascar, Germany, Great Britain, and Russia. They are cha ...

, 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 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 flying and gliding animals, gliding animals and by aircraft such as glider (aircraft), gl ...

, similar to living gliding '' Draco'' lizards. ''Coelurosauravus'' is solely known from the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

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

Lower Sakamena Formation Lower may refer to: * ''Lower'' (album), 2025 album by Benjamin Booker *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 sit ...

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

. The species '' Weigeltisaurus jaekeli'' from Europe was formerly considered a species of ''Coelurosauravus'', but is now placed in its own genus.

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. 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 lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

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

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

), 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 Robert "Bob" Lynn Carroll (May 5, 1938 – April 7, 2020) was an American–Canadian vertebrate paleontologist who specialised in Paleozoic and Mesozoic amphibians and reptiles. Biography Carroll was an only child and grew up on a farm nea ...

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 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 ...

. 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 known as a cranial suture, form the sides and roof of the neurocranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four bord ...

, which is also shared with '' Glaurung''. 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 weigeltisaurids, the penultimate

phalanges The phalanges (: phalanx ) are digit (anatomy), digital bones in the hands and foot, feet of most vertebrates. In primates, the Thumb, thumbs and Hallux, big toes have two phalanges while the other Digit (anatomy), digits have three phalanges. ...

are elongated, which in combination with their recurved

ungual An ungual (from Latin ''unguis'', i.e. ''nail'') is a highly modified distal toe bone which ends in a hoof, claw, or nail. Elephants and ungulates have ungual phalanges, as did the sauropod Sauropoda (), whose members are known as sauropods (; ...

s indicative of

claw 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 Arthro ...

s were likely an adaption to cling to tree bark. At least 29 pairs of long, elongate rod-shaped bones project from the sides of the body, dubbed "patagials". These are roughly equally spaced along the trunk. The first nine patagials show a rapid increase in size, with the ninth being the longest of all of the patagials, with the remaining pairs gradually decreasing in size posteriorly. When fully opened, each patagial membrane would have had a wingspan of .

Paleobiology

Though no stomach contents have been found, ''Coelurosauravus'' and other weigeltisaurids 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 (scansorial), but others are exclusively arboreal. The hab ...

insectivore file:Common brown robberfly with prey.jpg, A Asilidae, robber fly eating a hoverfly An insectivore is a carnivore, carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the Entomophagy ...

s. 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 Abdominal muscles cover the anterior and lateral abdominal region and meet at the anterior midline. These muscles of the anterolateral abdominal wall can be divided into four groups: the external obliques, the internal obliques, the transversus abd ...

. Preserved fossils of ''Weigeltisaurus'' show that the bony rods had a high degree of flexibility, 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 weight of an aircraft or flying animal divided by the area of its wing. The stalling speed, takeoff speed and landing speed of an aircraft are partly determined by its wing loading. The faster an airc ...

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 Sakamena 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 produced 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 ...

, perhaps similar to

Lake Tanganyika Lake Tanganyika ( ; ) is an African Great Lakes, African Great Lake. It is the world's List of lakes by volume, second-largest freshwater lake by volume and the List of lakes by depth, second deepest, in both cases after Lake Baikal in Siberia. ...

. 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 gymnosperm '' Glossopteris'', and seed fern ''

Lepidopteris ''Lepidopteris'' ("scaly fern") is a form classification, form genus for leaves of Peltaspermaceae, an extinct family of seed plants, which lived from around 260 to 190 million years ago, from the Late Permian to Early Jurassic. Fossils of the ge ...

.'' Other vertebrates known from the Lower Sakamena Formation include the palaeoniscoid fish '' Atherstonia'', the procolophonid parareptile '' Barasaurus'', the neodiapsids '' Hovasaurus,

Claudiosaurus ''Claudiosaurus'' (''claudus'' is Latin for 'lameness' and ''saurus'' means 'lizard') is an extinct genus of diapsid reptiles from the Late Permian Sakamena Formation of the Morondava Basin, Madagascar. It has been suggested to be semi-aquatic. ...

, Thadeosaurus'', and '' Acerosodontosaurus'', fragments of rhinesuchid

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

, an indeterminate

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, ...

therapsid and the

dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivores that typically bore a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, t ...

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