Weigeltisauridae

{{Short description|Extinct family of reptiles}} {{Automatic taxobox | taxon = Weigeltisauridae | fossil_range = Lopingian {{fossilrange|259.51|251.9}} {{period fossil range|Permian|Lopingian}} | image = SMNK-PAL 2882.png | image_caption = Skeleton of ''Weigeltisaurus'' | authority = Kuhn, 1939 | subdivision_ranks = Genera | subdivision = *{{extinct}}''Coelurosauravus'' *{{extinct}}''Glaurung''<ref>V. V. Bulanov; A. G. Sennikov (2015). "Glaurung schneideri gen. et sp. nov., a New Weigeltisaurid (Reptilia) from the Kupfershiefer (Upper Permian) of Germany". Paleontological Journal. 49 (12): 1353–1364. doi:10.1134/S0031030115120035.</ref> *{{extinct}}''Rautiania'' *{{extinct}}''Weigeltisaurus'' | synonyms = * Coelurosauravidae <small>Evans, 1982</small> }} '''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 characterized by long, hollow rod-shaped bones dubbed "patagials", which are unique to weigeltisaurids, extending from the lower torso that are suggested to have supported wing-like membranes.<ref>{{cite journal |title= The first gliding reptiles from the upper Permian of Russia|journal=Paleontological Journal|volume=40|issue=5|pages=S567–S570|doi=10.1134/S0031030106110037|date=October 2006|last1=Sennikov|first1=A. G.|last2=Bulanov|first2=V. V.|bibcode=2006PalJ...40S.567B |s2cid=84310001}}</ref><ref name=":4" /> Similar membranes have also evolved in other extinct reptiles such as kuehneosaurids and ''Mecistotrachelos'', as well as living gliding lizards, which are instead supported by the ribs.

== Description ==

{{multiple image | align = center | width = | footer = | image2 = Gliding reptile size comparison.svg | image1 = Coelurosauravus.svg | image3 = Weigeltisaurus jaekeli diagram.png | total_width = 800 | caption1 = Skull diagram of ''Coelurosauravus'' | caption3 = Diagram of the skeleton of ''Weigeltisaurus'' (gastralia are omitted) | caption2 = Comparison of the size and body proportions of two weigeltisaurids (''Coelurosauravus'' and ''Weigeltisaurus'', left) compared to a human hand, the much smaller living gliding lizard ''Draco volans'', and various unrelated extinct gliding reptiles | direction = horizontal }}

Weigeltisaurid skulls range from around {{Convert|3.4-3.7|cm}} long in ''Coelurosauravus'' to {{Convert|6|cm}} in length in ''Weigeltisaurus''.<ref name=":1">{{Cite journal|last1=Bulanov|first1=V.V.|last2=Sennikov|first2=A.G.|date=2015|title=Substantiation of Validity of the Late Permian Genus ''Weigeltisaurus'' Kuhn, 1939 (Reptilia, Weigeltisauridae)|url=https://www.researchgate.net/publication/284156582|journal=Paleontological Journal|volume=49|issue=10|pages=1101–1111|doi=10.1134/S0031030115110039|bibcode=2015PalJ...49.1101B|s2cid=85660972}}</ref> ''Coelurosauravus'' had a combined head and trunk length (snout-vent length) of around {{Convert|18|cm}} and a total length of at least {{Convert|32|cm}} including the tail.<ref name=":3" /> The skulls and jaws of weigeltisaurids are ornamented with horns and tubercles, including chameleon-like frills.<ref name=":0" /> The torso and limbs are slender. The skeletons of weigeltisaurds are lightened by large air spaces (skeletal pneumaticity) within the bones. The phalanges of the hands and feet are elongate contrasting strongly with those of most other primitive diapsids, but are similar to those of modern arboreal (tree-climbing) lizards.<ref name="BS10">{{Cite journal |last1=Bulanov |first1=V. V. |last2=Sennikov |first2=A. G. |year=2010 |title=New data on the morphology of Permian gliding weigeltisaurid reptiles of Eastern Europe |journal=Paleontological Journal |volume=44 |issue=6 |page=682 |doi=10.1134/S0031030110060109 |bibcode=2010PalJ...44..682B |s2cid=85212782}}</ref><ref name=":0" /> Unique to weigeltisaurids, the group possesses between 25 and 30 pairs of long, hollow rod-like bones, which project from the lower abdomen dubbed "patagials" <ref name=":0" /> These patagial bones, which appear to be novel (neomorphic) bones not found in any other reptile group, have a 1 to 1 correspondence with the gastralia (elongate, thin, crescent-shaped bones found in the lower belly) and appear to articulate with the lateral (outer) gastralia elements. In life, these patagials are thought to have been embedded in a membrane, which connected them, forming a foldable wing. This differs from the situation in living gliding lizards, and the fossil gliding reptiles ''Xianglong'', ''Mecistotrachelos'' and kuehneosaurids, where elongated ribs instead fulfill this role.<ref name=":4">{{Cite journal|title=Morphology and osteo‐histology of the weigeltisaurid wing: Implications for aerial locomotion in the world's first gliding reptiles|url=https://onlinelibrary.wiley.com/doi/10.1111/joa.70058|journal=Journal of Anatomy|date=2025-10-27|issn=0021-8782|doi=10.1111/joa.70058|language=en|first=Valentin|last=Buffa|first2=Jordan|last2=Gônet|first3=Thomas|last3=van de Kamp|first4=Marcus|last4=Zuber|first5=Marc|last5=Girondot|first6=Eberhard|last6=Frey|first7=J.‐Sébastien|last7=Steyer|first8=Michel|last8=Laurin}}</ref> These wings had a wingspan of around {{Convert|35|cm}} in ''Coelurosauravus''.<ref name=":3" />

== Paleobiology == [[File:Weigeltisaurus reconstruction.png|thumb|Life restoration of ''Weigeltisaurus jaekeli'']] Weigeltisaurids have been suggested to be arboreal (tree-dwelling) insectivores.<ref>{{Cite journal|last1=Bulanov|first1=V. V.|last2=Sennikov|first2=A. G.|date=2006-10-01|title=The first gliding reptiles from the upper Permian of Russia|journal=Paleontological Journal|language=en|volume=40|issue=5|pages=S567–S570|doi=10.1134/S0031030106110037|bibcode=2006PalJ...40S.567B |s2cid=84310001|issn=1555-6174}}</ref> 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.<ref name="BS10" /> The cranial ornamentation may have served a display purpose.<ref name=":2">{{Cite journal|last1=Buffa|first1=Valentin|last2=Frey|first2=Eberhard|last3=Steyer|first3=J.-Sébastien|last4=Laurin|first4=Michel|date=2021-07-12|title=A new cranial reconstruction of Coelurosauravus elivensis Piveteau, 1926 (Diapsida, Weigeltisauridae) and its implications on the paleoecology of the first gliding vertebrates|url=https://www.tandfonline.com/doi/full/10.1080/02724634.2021.1930020|journal=Journal of Vertebrate Paleontology|volume=41|issue=2|language=en|article-number=e1930020|doi=10.1080/02724634.2021.1930020|bibcode=2021JVPal..41E0020B |s2cid=237517962|issn=0272-4634}}</ref>

=== Gliding === [[File:Weigeltisauridae trunk cross section.jpg|thumb|Trunk cross section diagram of a weigeltisaurid, showing articulation of the patagial bones (pata) embedded within the ''M. obliquus externus'' (oes) with the gastralia (gas) ]] The gliding membrane of weigeltisaurids originated lower-lateral surface of the body unlike those of rib-gliding reptiles. The furling and unfurling of the gliding membrane were likely controlled by the abdominal muscles, probably the ''M. obliquus externus''.<ref name=":4" /> The patagial bones may have been connected to each other by tendons and muscles, which may have made them naturally tend towards a folded state.<ref name=":4" /> The patagial bones had a dumbbell-shaped cross section, which enhanced their rigidity enough to be able to be opened into a wing during flight without collapsing,<ref name=":4" /> though the outer tips of the patagial bones appear to have been somewhat flexible.<ref name=":0" /> Due to the low-wing configuration, it is likely that the gliding surface was angled upwards to increase stability.<ref name=":0" /> In living gliding lizards, it has been found that the forelimbs grab hold of the membrane during takeoff, allowing them to adjust their trajectory mid-flight. Similar behaviour has been proposed for weigeltisaurids,<ref name=":22">{{Cite journal|last=Dehling|first=J. Maximilian|date=2017-12-13|title=How lizards fly: A novel type of wing in animals|journal=PLOS ONE|language=en|volume=12|issue=12|article-number=e0189573|doi=10.1371/journal.pone.0189573|pmc=5728497|pmid=29236777|bibcode=2017PLoSO..1289573D|doi-access=free}}</ref> 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.<ref name=":3">{{Cite journal |last1=Buffa |first1=Valentin |last2=Frey |first2=Eberhard |last3=Steyer |first3=J.-Sébastien |last4=Laurin |first4=Michel |date=2022-09-08 |title=The postcranial skeleton of the gliding reptile Coelurosauravus elivensis Piveteau, 1926 (Diapsida, Weigeltisauridae) from the late Permian Of Madagascar |journal=Journal of Vertebrate Paleontology |volume=42 |issue=1 |language=en |article-number=e2108713 |doi=10.1080/02724634.2022.2108713 |bibcode=2022JVPal..42E8713B |s2cid=252173865 |issn=0272-4634|doi-access=free }}</ref> 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,<ref>{{Cite journal|last1=McGuire|first1=Jimmy A.|last2=Dudley|first2=Robert|date=2011-12-01|title=The Biology of Gliding in Flying Lizards (Genus Draco) and their Fossil and Extant Analogs|journal=Integrative and Comparative Biology|volume=51|issue=6|pages=983–990|doi=10.1093/icb/icr090|pmid=21798987|issn=1540-7063|doi-access=free}}</ref> though a later 2025 study found that the body mass of ''Coelurosauravus'' had been overestimated and that it would have been a relatively efficient glider.<ref name=":4" />

== Taxonomy ==

=== Species === *''Coelurosauravus'' Lower Sakamena Formation, Madagascar * ''Weigeltisaurus'' Kupferschiefer, Germany, Marl Slate, England * ''Rautiania'' Vyasovka Formation, Russia * ''Glaurung'' Kupferschiefer, Germany ''Wapitisaurus'' from the Early Triassic of North America was initially suggested to be a member of this family, but this was subsequently doubted. A study published in 2023 found that was likely closely related to thalattosaurs instead.<ref>{{Cite journal |last1=Bastiaans|first1=Dylan|last2=Buffa|first2=Valentin|last3=Scheyer|first3=Torsten M.|date=November 2023|title=To glide or to swim? A reinvestigation of the enigmatic Wapitisaurus problematicus (Reptilia) from the Early Triassic of British Columbia, Canada|journal=Royal Society Open Science|language=en|volume=10|issue=11|article-number=231171|doi=10.1098/rsos.231171|pmid=38026014|pmc=10646446|issn=2054-5703|doi-access=free|bibcode=2023RSOS...1031171B}}</ref>

=== Relationships to other reptiles === Weigeltisaurids have generally been interpreted as neodiapsids that lie outside of Sauria (the group containing all living diapsids and probably all living reptiles including birds). Their relative position compared to other basal diapsid groups like the Younginiformes has varied between studies.<ref name=":6">{{Cite journal |last1=Buffa |first1=Valentin |last2=Frey |first2=Eberhard |last3=Steyer |first3=J-Sébastien |last4=Laurin |first4=Michel |date=2024-05-11 |title='Birds' of two feathers: Avicranium renestoi and the paraphyly of bird-headed reptiles (Diapsida: 'Avicephala') |journal=Zoological Journal of the Linnean Society |volume=202 |issue=4 |article-number=zlae050 |language=en |doi=10.1093/zoolinnean/zlae050 |issn=0024-4082|doi-access=free }}</ref> It has been controversially proposed that they are closely related to the drepanosaurs, a group of arboreal diapsids native to northern Pangaea during the Late Triassic. The proposed clade containing the two groups was named Avicephala by Senter in 2004.<ref>{{Cite journal|last=Senter|first=Phil|date=January 2004|title=Phylogeny of Drepanosauridae (Reptilia: Diapsida)|url=http://www.tandfonline.com/doi/abs/10.1017/S1477201904001427|journal=Journal of Systematic Palaeontology|language=en|volume=2|issue=3|pages=257–268|doi=10.1017/S1477201904001427|bibcode=2004JSPal...2..257S |s2cid=83840423|issn=1477-2019|url-access=subscription}}</ref> Proposed synapomorphies of the clade include "absence of intercentra in cervical region; absence of intercentra in dorsal region; scapulocoracoid, ratio of anteroposterior length at base of scapular blade to dorsoventral height of scapular blade between 0.4 and 0.25; outer process of fifth metatarsal absent."<ref name=":0">{{Cite journal|last1=Pritchard|first1=Adam C.|last2=Sues|first2=Hans-Dieter|last3=Scott|first3=Diane|last4=Reisz|first4=Robert R.|date=2021-05-20|title=Osteology, relationships and functional morphology of Weigeltisaurus jaekeli (Diapsida, Weigeltisauridae) based on a complete skeleton from the Upper Permian Kupferschiefer of Germany|journal=PeerJ|language=en|volume=9|article-number=e11413|doi=10.7717/peerj.11413|pmid=34055483|issn=2167-8359|pmc=8141288 |doi-access=free }}</ref> Other studies have recovered the two groups as unrelated, suggesting that drepanosaurs are archosauromorphs instead.<ref name=":6" />

Jenkins et al. (2025) recovered weigeltisaurids as basal neodiapsids, diverging after the 'younginiform' clades Younginidae and Tangasauridae. These results are displayed in the cladogram below:<ref>{{cite journal |last1=Jenkins|first1=Xavier A|last2=Benson|first2=Roger BJ|last3=Ford|first3=David P|last4=Browning|first4=Claire|last5=Fernandez|first5=Vincent|last6=Dollman|first6=Kathleen|last7=Gomes|first7=Timothy|last8=Griffiths|first8=Elizabeth|last9=Choiniere|first9=Jonah N|last10=Peecook|first10=Brandon R|date=28 August 2025|title=Evolutionary assembly of crown reptile anatomy clarified by late Paleozoic relatives of Neodiapsida|journal=Peer Community Journal|volume=5|article-number=e89|doi=10.24072/pcjournal.620|eissn=2804-3871|s2cid=274305322|doi-access=free}}</ref> {{clade|{{clade | 1={{extinct}}Araeoscelidia 65px | 2={{clade | 1={{extinct}}Bolosauridae 60px | label2=Neoreptilia | 2={{clade | label1={{extinct}}Ankyramorpha | 1={{clade | 1={{extinct}}Acleistorhinidae 60px | 2={{clade | 1={{extinct}}Pareiasauromorpha <div style="{{MirrorH}}">60px</div> | 2={{extinct}}Procolophonoidea 60px }} }} | 2={{clade | 1={{extinct}}Mesosauridae <div style="{{MirrorH}}">65px</div> | 2={{clade | 1={{clade | 1={{extinct}}''Cabarzia'' | 2={{clade | 1={{extinct}}''Ascendonanus'' | 2={{extinct}}''Orovenator'' <div style="{{MirrorH}}">60px</div> }} }} | label2=Parapleurota | 2={{clade | 1={{extinct}}Millerettidae <div style="{{MirrorH}}">60px</div> | label2=Neodiapsida | 2={{clade |label1= |1={{extinct}}Younginidae <div style="{{MirrorH}}">60px</div> |3={{clade |label1= |1={{extinct}}Tangasauridae 60px |3={{clade | 1={{extinct}}'''Weigeltisauridae''' <div style="{{MirrorH}}">60px</div> | 2={{clade | 1={{extinct}}''Claudiosaurus'' 60px |label2=Sauria |2={{clade |1=Lepidosauromorpha 65px |2=Archosauromorpha <span style="{{MirrorH}}">60px</span> }} }} }} }} }} }} }} }} }} }} }}|style=|label1=Sauropsida}}

==References== {{Reflist}}

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{{Sauropsida|N.}} {{Taxonbar|from=Q5140707}}

Category:Weigeltisauridae Category:Lopingian first appearances Category:Early Triassic extinctions Category:Prehistoric reptile families