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''Slavoia'' is an extinct genus of
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).
lizard
Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...
from the Early Cretaceous
The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...
of Mongolia
Mongolia is a landlocked country in East Asia, bordered by Russia to the north and China to the south and southeast. It covers an area of , with a population of 3.5 million, making it the world's List of countries and dependencies by po ...
( Dzunbain Formation), and Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...
of Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...
( Bostobe Formation) and Mongolia
Mongolia is a landlocked country in East Asia, bordered by Russia to the north and China to the south and southeast. It covers an area of , with a population of 3.5 million, making it the world's List of countries and dependencies by po ...
( 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 amphisbaenia
Amphisbaenia (called amphisbaenians or worm lizards) is a group of typically legless lizards, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. A ...
ns.
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'' withinScincomorpha
Scincomorpha is an infraorder and clade of lizards including skinks (Scincidae) and their close relatives. These include the living families Cordylidae (girdled lizards), Gerrhosauridae (plated lizards), and Xantusiidae (night lizards), as well a ...
. Conrad (2008) placed in a clade containing Lacertoidea
The Lacertoidea is a group of squamate reptiles that includes the Lacertidae, Teiidae, Gymnophthalmidae, and Amphisbaenia. The finding from molecular phylogenetic studies that the burrowing Amphisbaenia were nested in a clade with the lizard form ...
+Scincomorpha. Tałanda (2016, 2017), who provided a new description of the genus, placed it as a stem-group relative of amphisbaenia
Amphisbaenia (called amphisbaenians or worm lizards) is a group of typically legless lizards, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. A ...
ns within Lacertoidea.
References
{{Taxonbar, from=Q21368951 Prehistoric reptile genera Late Cretaceous reptiles of Asia Fossil taxa described in 1984