Araeoscelidia

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Extinct clade of reptiles

title: "Araeoscelidia" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["araeoscelidia", "pennsylvanian-first-appearances", "cisuralian-extinctions", "taxa-named-by-samuel-wendell-williston"] description: "Extinct clade of reptiles" topic_path: "general/araeoscelidia" source: "https://en.wikipedia.org/wiki/Araeoscelidia" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extinct clade of reptiles ::

| name = Araeoscelidans | fossil_range = Carboniferous–Permian | image = Petrolacosaurus BW.jpg | image_caption = | image2 = Petrolacosaurus skull diagram.png | image2_caption = Life restoration (top) and skull reconstruction (bottom) of Petrolacosaurus kansensis | taxon = Araeoscelidia | authority = Williston, 1913 | subdivision_ranks = Genera | subdivision =

Araeoscelidia or Araeoscelida is a clade of extinct tetrapods (traditionally classified as diapsid reptiles) superficially resembling lizards, extending from the Late Carboniferous to the Early Permian. The group contains the genera Araeoscelis, Petrolacosaurus, the possibly aquatic Spinoaequalis, and less well-known genera such as Kadaliosaurus and Zarcasaurus. This clade is usually considered to be the sister group to all (currently known) later diapsids.

Description

Araeoscelidians were small animals (less than one meter in length) looking somewhat like lizards, though they are only distantly related to true lizards. They differ from other, earlier sauropsids by their slender limbs, their elongated tail, and of course by the presence of two temporal openings, the feature defining the diapsid condition. In Araeoscelis, only the upper temporal opening remains, thus resulting in a derived euryapsid condition.

Genera

Araeoscelidia includes well-known genera such as Araeoscelis Williston 1910, Petrolacosaurus Lane 1945 and Spinoaequalis, known from virtually complete skeletons. Zarcasaurus, Aphelosaurus and Kadaliosaurus belong to this clade but are known only from post-cranial remains and a mandible fragment for Zarcasaurus.

The genus Dictybolos has been included in Araeoscelidia by Olson (1970) but this inclusion has been criticized e.g., by Evans (1988), especially since Olson also included distantly related groups such as protorosaurs and mesosaurs.

New specimens have been discovered in the United States state of Oklahoma, but lack a scientific description as of 2023.

Phylogeny

The majority of historical phylogenetic studies recovered araeoscelidians as the most basal group of diapsids:

Cladogram after Bickelmann et al., 2009 and Reisz et al., 2011:{{clade|{{clade |label1=Sauropsida |1={{clade |label1=Parareptilia |1={{clade |1={{clade |label1= |1=Millerettidae [[Image:Milleretta BW.jpg|50px]] |label2= |2={{clade |1={{clade |label1= |1= Eunotosaurus |label2=Hallucicrania |2={{clade |1=Lanthanosuchidae [[Image:Lanthanosuchus watsoni.jpg|50px]] |label2=Procolophonia |2={{clade |label1= |1=Procolophonoidea [[Image:Sclerosaurus1DB.jpg|50px]] |2=Pareiasauromorpha [[Image:Scutosaurus BW.jpg|60px]] |label2=Eureptilia |2={{clade |1={{clade |label1= |1= Captorhinidae [[Image:Labidosaurus.jpg|50px]] |label2=Romeriida |2={{clade |1={{clade |label1= |1=Paleothyris |label2=Diapsida |2={{clade |1=Araeoscelidia |label2=Neodiapsida |2={{clade |label1= |1=Orovenator |2={{clade |label1= |1=Lanthanolania |2={{clade |label1= |1=Tangasauridae |2={{clade |label1= |1=Younginidae |2={{clade |label1= |1={{clade |label1= |1=Claudiosaurus |2={{clade |label1= |1={{clade |label1= |1={{clade |label1= |1=Palaeagama |2=Saurosternon |2={{clade |label1= |1={{clade |label1= |1=Coelurosauravus |2={{clade |1={{clade |label1= |1=Thalattosauria |2={{clade |label1= |1=Hupehsuchia |2=Ichthyopterygia |label2=Sauria |2={{clade |label1= |1=Lepidosauromorpha |2=Archosauromorpha |1=Seymouriamorpha [[File:Seymouria BW.jpg|100px]] |2={{clade |1=Diadectomorpha [[File:Limnoscelis21DB.jpg|100px]] |2={{clade |1={{clade |1=Araeoscelidia [[File:Petrolacosaurus_BW.jpg|100px]] |2={{clade |1=Protorothyris [[File:Protorothyris.jpg|100px]] |2=Captorhinidae [[File:Moradisaurus.jpg|100px]] |label2=Amniota |2={{clade |1=Synapsida [[File:Dimetrodon milleri.jpg|100px]] |label2=Sauropsida |2={{clade |1=Acleistorhinidae [[File:Carbonodraco lundi.png|100px]] |2={{clade |1=Millerettidae [[File:Milleretta BW.jpg|100px]] |2={{clade |1=Mesosauria [[File:Mesosaurus_BW.jpg|100px]] |label2=Neoreptilia |2={{clade |1=Procolophonia [[File:Scutosaurus BW flipped.jpg|100px]] |2=Neodiapsida (including modern reptiles and birds)

Stratigraphic and geographic distribution

Araeoscelidia are known from the Late Carboniferous in the United States (Petrolacosaurus, Spinoaequalis) to the Early Permian in France (Aphelosaurus), Germany (Kadaliosaurus) and the United States (Dictybolos, Zarcasaurus, Araeoscelis, Halgaitosaurus). Apart from araeoscelidans, only one other diapsid is known before the Late Permian: Orovenator from the Early Permian of Oklahoma.

References

Bibliography

References

  1. {{harvnb. Vaughn. 1955
  2. {{harvnb. Reisz. Berman. Scott. 1984
  3. {{harvnb. Peabody. 1952
  4. {{harvnb. Reisz. 1981
  5. {{harvnb. deBraga. Reisz. 1995
  6. {{harvnb. deBraga. Rieppel. 1997
  7. {{harvnb. Brinkman. Berman. Eberth. 1984
  8. {{harvnb. Gervais. 1859
  9. {{harvnb. Thévenin. 1910
  10. {{harvnb. Falconnet. Steyer. 2007
  11. {{harvnb. Credner. 1889
  12. {{harvnb. Olson. 1970
  13. {{harvnb. Evans. 1988
  14. {{harvnb. May. Hall. 2002
  15. {{harvnb. Swanson. Carlson. 2002
  16. (2009). "The enigmatic diapsid ''Acerosodontosaurus piveteaui'' (Reptilia: Neodiapsida) from the Upper Permian of Madagascar and the paraphyly of ''younginiform'' reptiles". Canadian Journal of Earth Sciences.
  17. (2022). "Successive climate crises in the deep past drove the early evolution and radiation of reptiles". Science Advances.
  18. Henrici, Amy C.. (2023-11-15). "Halgaitosaurus gregarius, a New Upper Carboniferous Araeoscelidian (Reptilia: Diapsida) from the Halgaito Formation, Bears Ears National Monument, Utah, USA". Annals of Carnegie Museum.

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