Araeoscelidia or Araeoscelida is a clade of extinct amniotes (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.

Araeoscelidans
Temporal range: CarboniferousPermian 302–275.6 Ma
Life restoration (top) and skull reconstruction (bottom) of Petrolacosaurus kansensis
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Diapsida
Order: Araeoscelidia
Williston, 1913
Genera

Description

edit

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

edit

Araeoscelidia includes well-known genera such as Araeoscelis Williston 1910,[1][2] Petrolacosaurus Lane 1945[3][4] and Spinoaequalis,[5][6] known from virtually complete skeletons. Zarcasaurus,[7] Aphelosaurus[8][9][10] and Kadaliosaurus[11] 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)[12] but this inclusion has been criticized e.g., by Evans (1988),[13] 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,[14][15] but lack a scientific description as of 2023.

Phylogeny

edit

The majority of phylogenetic studies recover araeoscelidians as the most basal group of diapsids; however, Simões et al. (2022) recover them as stem-amniotes instead, as the sister group to the clade including Captorhinidae and Protorothyris archeri.[16]

Stratigraphic and geographic distribution

edit

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[17]). Apart from araeoscelidans, only one other diapsid is known before the Late Permian: Orovenator from the Early Permian of Oklahoma.[18]

References

edit
  1. ^ Vaughn 1955
  2. ^ Reisz, Berman & Scott 1984
  3. ^ Peabody 1952
  4. ^ Reisz 1981
  5. ^ deBraga & Reisz 1995
  6. ^ deBraga & Rieppel 1997
  7. ^ Brinkman, Berman & Eberth 1984
  8. ^ Gervais 1859
  9. ^ Thévenin 1910
  10. ^ Falconnet & Steyer 2007
  11. ^ Credner 1889
  12. ^ Olson 1970
  13. ^ Evans 1988
  14. ^ May & Hall 2002
  15. ^ Swanson & Carlson 2002
  16. ^ Simões, T. R.; Kammerer, C. F.; Caldwell, M. W.; Pierce, S. E. (2022). "Successive climate crises in the deep past drove the early evolution and radiation of reptiles". Science Advances. 8 (33): eabq1898. doi:10.1126/sciadv.abq1898. PMC 9390993. PMID 35984885.
  17. ^ Henrici, Amy C.; Berman, David S; Sumida, Stuart S.; Huttenlocker, Adam K. (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. 88 (3). doi:10.2992/007.088.0301. ISSN 0097-4463.
  18. ^ Reisz, Modesto & Scott 2011

Further reading

edit