Lepidosauromorpha

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Lepidosauromorphs
Temporal range:
Earliest Triassic - Holocene,[1]
Skull of Sophineta cracoviensis
Collage of five lepidosaurs. From top left to right: Sphenodon punctatus, Dendroaspis polylepis, Iguana iguana, Smaug breyeri and Malayopython reticulatus.
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Sauria
Clade: Lepidosauromorpha
Benton, 1983
Subgroups

See text.

Synonyms

Lepidosauromorpha (in PhyloCode known as Pan-Lepidosauria)[2][3] is a group of reptiles comprising all diapsids closer to lizards than to archosaurs (extant archosaurs are crocodiles and birds). The only living sub-group is the Lepidosauria, which contains two subdivisions, Squamata, which contains lizards and snakes, and Rhynchocephalia, the only extant species of which is the tuatara.

The defining characters (synapomorphies) ancestral for Lepidosauromorpha include several characters of the skull and lower jaws, including the reduction in the size of the lacrimal bone, the posterior process (extension/growth) of the jugal bone being short, reduced or absent interdental (between teeth) plates/laminae, and the wall of bone enclosing the teeth from the mouth on the inner surface of the upper and lower jaws being reduced or absent,[4] corresponding with the development of an ancestrally pleurodont dentition.[4] Members of the group are ancestrally and are almost exclusively (with the exception of mosasaurs) ectothermic (cold-blooded).[5] Members of the group generally have a sprawling posture.[6]

While some putative stem-lepidosauromorphs like Palaeagama are known from the Late Permian, the oldest definitive lepidosauromorphs, Sophineta and Paliguana, are known from the Early Triassic.[7][8] Taytalura from the early Late Triassic of Argentina is the most complete fossil of an early lepidosauromorph and is one of the few fossils robustly inferred as an early evolving lepidosauromorph.[9] The Kuehneosauridae, a family of reptiles with elongated ribs which allowed them to glide akin to living gliding lizards have been historically typically considered early lepidosauromorphs. However, several recent studies have been found them in other positions within Sauria, including Archosauromorpha.[10]

Almost all non-lepidosaurian lepidosauromorphs became extinct by the end of the Triassic, the with the latest non lepidosaur-lepidosauromorphs being Marmoretta from the Middle-Late Jurassic of Britain and Iberia, and an indeterminate form from the Middle Jurassic Moskvoretskaya Formation of Russia, which appear to be closely related to Fraxinisaura from the Middle Triassic of Germany.[8][11][12] Other studies have recovered Marmoretta as a stem-squamate.[13]

Subgroups

Phylogeny

Cladogram after Sobral and Schoch, 2026 with equal-weights parsimony:[4]

Strict consensus cladogram also after Sobral and Schoch, 2026.[4]

See also

References

  1. Jones, M. E.; Anderson, C.; Hipsley, C. A.; Müller, J.; Evans, S. E.; Schoch, R. R. (2013). "Integration of molecules and new fossils supports a Triassic origin for Lepidosauria (lizards, snakes, and tuatara)". BMC Evolutionary Biology. 13 (1): 208. Bibcode:2013BMCEE..13..208J. doi:10.1186/1471-2148-13-208. PMC 4016551. PMID 24063680.
  2. de Queiroz, K.; Cantino, P. D.; Gauthier, J. A., eds. (2020). "Pan-Lepidosauria J. A. Gauthier and K. de Queiroz, new clade name". Phylonyms: A Companion to the PhyloCode. Boca Raton: CRC Press. pp. 1075–1078. ISBN 978-1-138-33293-5.
  3. "Pan-Lepidosauria". RegNum.
  4. Sobral, Gabriela; Schoch, Rainer R. (2026-01-02). "New stem lepidosaurs from Vellberg, Germany: implications for palaeoecology in the early diversification of Lepidosauromorpha". Journal of Systematic Palaeontology. 24 (1) 2603472. Bibcode:2026JSPal..2403472S. doi:10.1080/14772019.2025.2603472. ISSN 1477-2019.
  5. Grigg, Gordon; Nowack, Julia; Bicudo, José Eduardo Pereira Wilken; Bal, Naresh Chandra; Woodward, Holly N.; Seymour, Roger S. (April 2022). "Whole-body endothermy: ancient, homologous and widespread among the ancestors of mammals, birds and crocodylians". Biological Reviews. 97 (2): 766–801. Bibcode:2022BioRv..97..766G. doi:10.1111/brv.12822. ISSN 1464-7931. PMC 9300183. PMID 34894040.
  6. Regnault, Sophie; Jones, Marc E. H.; Pitsillides, Andrew A.; Hutchinson, John R. (May 2016). "Anatomy, morphology and evolution of the patella in squamate lizards and tuatara ( Sphenodon punctatus )". Journal of Anatomy. 228 (5): 864–876. doi:10.1111/joa.12435. ISSN 0021-8782. PMC 4831346. PMID 26740056.
  7. Susan E. Evans and Magdalena Borsuk−Białynicka (2009). "A small lepidosauromorph reptile from the Early Triassic of Poland" (PDF). Paleontologica Polonica. 65: 179–202.
  8. Ford, David P.; Evans, Susan E.; Choiniere, Jonah N.; Fernandez, Vincent; Benson, Roger B. J. (2021-08-25). "A reassessment of the enigmatic diapsid Paliguana whitei and the early history of Lepidosauromorpha". Proceedings of the Royal Society B: Biological Sciences. 288 (1957) 20211084. Bibcode:2021RSPSB.28811084F. doi:10.1098/rspb.2021.1084. PMC 8385343. PMID 34428965.
  9. Martínez, Ricardo N.; Simões, Tiago R.; Sobral, Gabriela; Apesteguía, Sebastián (2021-08-25). "A Triassic stem lepidosaur illuminates the origin of lizard-like reptiles". Nature. 597 (7875): 235–238. Bibcode:2021Natur.597..235M. doi:10.1038/s41586-021-03834-3. hdl:11336/154797. ISSN 1476-4687. PMID 34433961. S2CID 237307957.
  10. Queiroz, Kevin de; Cantino, Philip D.; Gauthier, Jacques A. (2020-04-30), "Pan-Lepidosauria J. A. Gauthier and K. de Queiroz, new clade name", in de Queiroz, Kevin; Cantino, Philip; Gauthier, Jacques (eds.), Phylonyms (1 ed.), Boca Raton, FL: CRC Press, pp. 1075–1078, doi:10.1201/9780429446276-255, ISBN 978-0-429-44627-6, S2CID 219018618, retrieved 2021-08-22
  11. Skutschas, Pavel P.; Sennikov, Andrey G.; Syromyatnikova, Elena V.; Vitenko, Dmitriy D.; Parakhin, Igor A.; Bapinaev, Roman A.; Evans, Susan E. (2021-06-09). "A lepidosauromorph specimen from the Middle Jurassic (Bathonian) Moskvoretskaya Formation of the Moscow Region, Russia". Historical Biology. 34 (3): 566–570. doi:10.1080/08912963.2021.1935921. ISSN 0891-2963. S2CID 236282947.
  12. Griffiths, E.; Ford, D. P.; Benson, R.; Evans, S. E. (2021). "New information on the Jurassic lepidosauromorph Marmoretta oxoniensis". Palaeontology. ISSN 0031-0239.
  13. Simōes, Tiago R.; Caldwell, Michael W.; Talanda, Mateusz; Bernardi, Massimo; Palci, Alessandro; Vernygora, Oksana; Bernardini, Federico; Mancini, Lucia; Nydam, Randall L. (30 May 2018). "The origin of squamates revealed by a Middle Triassic lizard from the Italian Alps". Nature. 557 (7707): 706–709. Bibcode:2018Natur.557..706S. doi:10.1038/s41586-018-0093-3. PMID 29849156. S2CID 44108416.