Weigeltisauridae is a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of gliding

neodiapsid Neodiapsida is a clade, or major branch, of the reptilian family tree, typically defined as including all diapsids apart from some early primitive types known as the araeoscelidians. Modern reptiles and birds belong to the neodiapsid subclade ...

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 rhynchocephalia ...

s that lived 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, ...

, between 258 and 252 million years ago. Fossils of weigeltisaurids have been found in Madagascar, Germany, Great Britain, and Russia. A possible weigeltisaurid, '' Wapitisaurus'', been found in Early

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest per ...

strata in North America, but its poor preservation makes referral to the group questionable. They are characterized by long, hollow rod-shaped bones extending from the torso that probably supported wing-like membranes. Similar membranes are also found in several other extinct reptiles such as

kuehneosaurid Kuehneosauridae is an extinct family of small, lizard-like gliding diapsids known from the Triassic period of Europe and North America. They are distinguished from other diapsids by their 'wings' formed by elongated ribs. These allowed the an ...

s and '' Mecistotrachelos'', as well as living

gliding lizard ''Draco'' is a genus of agamid lizards that are also known as flying lizards, flying dragons or gliding lizards. These lizards are capable of gliding flight via membranes that may be extended to create wings ( patagia), formed by an enlarged set ...

s, although each group evolved these structures independently.

Skeleton

The skulls and jaws of weigeltisaurids are ornamented with horns and tubercles, including chameleon-like frills. The torso and limbs are slender. The skeletons of weigeltisaurds are lightened by large air spaces ( skeletal pneumaticity) within the bones. The

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. ...

of the hands and feet are elongate contrasting strongly with those of most other primitive diapsids, but are similar to those of modern arboreal lizards. Unique to weigeltisaurids, the group possesses between 25 and 30 pairs of long, hollow rod-like bones, which project from the lower abdomen. These have been proposed to be modified

gastralia Gastralia (singular gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods. They are found between the sternum and pelvis, and do not articulate with the vertebrae. In thes ...

or otherwise a novel bone ossification. Weigeltisaurus jaekeli diagram

Paleobiology

Weigeltisaurids have been suggested to be arboreal insectivores. Their limb morphology was well adapted for grasping tree bark, including vertical tree trunks. Due to their limb morphology, they were highly adapted for movement in the trees, and would likely have not been capable of moving quickly or efficiently on the ground. The cranial ornamentation may have served a display purpose.

Gliding

The gliding membrane of weigeltisaurids is distinct from those of other gliding reptiles, which are modified ribs originating from the upper-lateral surface of the body. In contrast, in weigeltisaurids, 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 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, which 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'' 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 substantial drop in height per glide.

Relationships

Weigeltisaurids have generally been interpreted as primitive

neodiapsids Neodiapsida is a clade, or major branch, of the reptilian family tree, typically defined as including all diapsids apart from some early primitive types known as the araeoscelidians. Modern reptiles and birds belong to the neodiapsid subclade Sau ...

, that lie outside of

Sauria Sauria is the clade containing the most recent common ancestor of archosaurs (such as crocodilians, dinosaurs, etc.) and lepidosaurs ( lizards and kin), and all its descendants. Since most molecular phylogenies recover turtles as more closely ...

. It has been proposed that they are closely related to the drepanosaurs, a group of arboreal basal neodiapsids native to northern Pangaea during the

Late Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch ...

. The proposed

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

containing the two groups was named

Avicephala Avicephala ("bird heads") is an extinct, potentially polyphyletic grouping of diapsid reptiles that lived during the Late Permian and Triassic periods characterised by superficially bird-like skulls and arboreal lifestyles. As a clade, Avicephala ...

by Senter in 2004. Proposed

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ha ...

of the clade include "absence of intercentra in cervical region; absence of intercentra in dorsal region;

scapulocoracoid The scapulocoracoid is the unit of the pectoral girdle that contains the coracoid and scapula. The coracoid itself is a beak-shaped bone that is commonly found in most vertebrates with a few exceptions. The scapula is commonly known as the ''shoulde ...

, ratio of anteroposterior length at base of scapular blade to dorsoventral height of

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eith ...

r blade between 0.4 and 0.25; outer process of fifth

metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the me ...

absent."

Taxonomy

* ''

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 ossific ...

'' Lower Sakamena Formation, Madagascar * ''

Weigeltisaurus ''Weigeltisaurus'' is an extinct genus of weigeltisaurid reptile from the Late Permian Kupferschiefer of Germany and Marl Slate of England. It has a single species, originally named as ''Palaechamaeleo jaekeli'' in 1930 and later assigned the na ...

Kupferschiefer The Kupferschiefer ( German for Copper Shale, also called Copper Slate) or Kupfermergel (Copper Marl), (T1 or Z1) is an extensive and remarkable sedimentary unit in Central Europe. The relatively monotonous succession is typically and maximum t ...

, Germany, Marl Slate, England * '' Rautiania'' Vyasovka Formation, Russia * ''

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. ...

'' Kupferschiefer, Germany

References

Permian diapsids Triassic diapsids Avicephalans Lopingian first appearances Early Triassic extinctions Prehistoric reptile families {{triassic-reptile-stub