Slavoia

Not to be confused with Slavonia.

Slavoia
Temporal range: Early-Late Cretaceous,
~125–71 Ma
ZPAL MgR-I/8, the holotype specimen
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: †Slavoiidae
Genus: †Slavoia
Sulimski, 1984
Type species
†Slavoia darevskii
Sulimski, 1984

Slavoia is an extinct genus of lizard from the Early Cretaceous of Mongolia (Dzunbain Formation[1]), and Late Cretaceous of Kazakhstan (Bostobe Formation[2]) and Mongolia (Barun Goyot Formation and Djadochta Formation).

There is only a single species S. darevskii,[3] and Slavoia has been suggested to be the oldest known relative of amphisbaenians.

Description

Reconstructed skeleton of S. darevskii

The structure of the skull of Slavoia suggests that it may have had a fossorial (burrowing) lifestyle,[4][5] and when fully grown, it likely grew up to 12 centimetres (4.7 in) long.[6]

Slavoia is known from several specimens including the holotype ZPAL MgR-I/8,[3] mostly made up of incomplete skulls and skeletons, and it has therefore been possible to reconstruct its appearance.[5] Slavoia is characterized by a skull with a very compact structure, and the orbits were small, the parietal hole was small or non-existent. The teeth, pleurodonts, were robust. The premaxilla had five teeth, while the maxilla and jaw had seven or eight. The lacrimal bone was greatly reduced, and there were 26 presacral vertebrae, equipped with an anteriorly hollow vertebral centre (procelus).[3] Relative to most lizards, the limbs were relatively small, and the body was elongated, suggested to be adaptations for a burrowing lifestyle. The first digit of the hand had hyperphalangy (the presence of additional phalange bones).[5]

Classification

Alifanov (1993), Gao and Norell (2000), Kearney (2003) and Bolet et al. (2022) placed Slavoia within Scincomorpha.[7][8][9][10] Conrad (2008) placed in a clade containing Lacertoidea+Scincomorpha.[11] Tałanda (2016, 2017), who provided a new description of the genus, placed it as a stem-group relative of amphisbaenians within Lacertoidea.[12][5]

References

  1. ^ Alifanov V. R. (2000) The fossil record of Cretaceous lizards from Mongolia, The Age of Dinosaurs in Russia and Mongolia, 368-389
  2. ^ Kordikova, E. G.; Polly, P. D.; Alifanov, V. A.; Roček, Z.; Gunnell, G. F.; Averianov, A. O. (March 2001). "Small vertebrates from the late Cretaceous and early Tertiary of the northeastern Aral Sea region, Kazakhstan". Journal of Paleontology. 75 (2): 390–400. doi:10.1017/s0022336000018187. ISSN 0022-3360.
  3. ^ a b c Sulimski, A. (1984). A new Cretaceous scincomorph lizard from Mongolia. Palaeontologia Polonica 46:143-155
  4. ^ Tałanda, Mateusz (2015). "Cretaceous roots of the amphisbaenian lizards". Zoologica Scripta. 45 (1): 1–8. doi:10.1111/zsc.12138. ISSN 0300-3256. S2CID 85570915.
  5. ^ a b c d Tałanda, Mateusz (2017). "Evolution of postcranial skeleton in worm lizards inferred from its status in the Cretaceous stem-amphisbaenian Slavoia darevskii". Acta Palaeontologica Polonica. 62. doi:10.4202/app.00294.2016. ISSN 0567-7920.
  6. ^ "Slavoia". Nix Illustration. Retrieved 5 September 2023.
  7. ^ Alifanov, Vladimir. (1993). Some peculiarities of the Cretaceous and Palaeogene lizard faunas of the Mongolian People's Republic. Kaupia. 3. 9-13.
  8. ^ Gao, K.-Q. M. A. Norell. (2000) Taxonomic composition and systematics of Late Cretaceous lizard assemblages from Ukhaa Tolgod and adjacent localities, Mongolian Gobi Desert. "Bulletin of the American Museum of Natural History". 249, s. 1-118,
  9. ^ Kearney, M. (2003) The phylogenetic position of Sineoamphisbaena hexatabularis reexamined. "Journal of Vertebrate Paleontology". 23, s. 394-403,
  10. ^ Bolet, Arnau; Stubbs, Thomas L; Herrera-Flores, Jorge A; Benton, Michael J (2022-05-03). Zhu, Min; Perry, George H; Zhu, Min (eds.). "The Jurassic rise of squamates as supported by lepidosaur disparity and evolutionary rates". eLife. 11: e66511. doi:10.7554/eLife.66511. ISSN 2050-084X. PMC 9064307. PMID 35502582.
  11. ^ Conrad, J. L.. (2008) Phylogeny and systematics of Squamata (Reptilia) based on morphology. "Bulletin of the American Museum of Natural History". 310, s. 1-182,
  12. ^ Tałanda, Mateusz (January 2016). "Cretaceous roots of the amphisbaenian lizards". Zoologica Scripta. 45 (1): 1–8. doi:10.1111/zsc.12138. ISSN 0300-3256. S2CID 85570915.