Slavoia is an extinct genus of lizard from the Early Cretaceous of Mongolia (Dzunbain FormationAlifanov V. R. (2000) The fossil record of Cretaceous lizards from Mongolia, The Age of Dinosaurs in Russia and Mongolia, 368-389), and Late Cretaceous of Kazakhstan (Bostobe Formation) and Mongolia (Barun Goyot Formation and Djadochta Formation).
There is only a single species S. darevskii,Sulimski, A. (1984). A new Cretaceous scincomorph lizard from Mongolia. Palaeontologia Polonica 46:143-155 and Slavoia has been suggested to be the oldest known relative of amphisbaenians.
Description
The structure of the skull of Slavoia suggests that it may have had a fossorial (burrowing) lifestyle, and when fully grown, it likely grew up to long.
Slavoia is known from several specimens including the holotype ZPAL MgR-I/8, mostly made up of incomplete skulls and skeletons, and it has therefore been possible to reconstruct its appearance. 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). 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).
Classification Alifanov (1993), Gao and Norell (2000), Kearney (2003) and Bolet et al. (2022) placed Slavoia within Scincomorpha.Alifanov, Vladimir. (1993). Some peculiarities of the Cretaceous and Palaeogene lizard faunas of the Mongolian People's Republic. Kaupia. 3. 9-13.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,Kearney, M. (2003) The phylogenetic position of Sineoamphisbaena hexatabularis reexamined. "Journal of Vertebrate Paleontology". 23, s. 394-403, Conrad (2008) placed in a clade containing Lacertoidea+Scincomorpha.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, Tałanda (2016, 2017), who provided a new description of the genus, placed it as a stem-group relative of amphisbaenians within Lacertoidea.
References