''Sciroseps'' is an extinct genus of scincomorph

squamates Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, it ...

known from a partial left mandible, UA-2016-13-294, from the Early Cretaceous (

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0 ...

) Holly Creek Formation of the Trinity Group in Arkansas, USA. The type and only species is ''Sciroseps pawhuskai''. Its generic name is derived from Greek ''"σκυρος: skiros" (gypsum),'' and ''"σεπος: sepos" (lizard or snake);'' and its species name refers to historic Osage chief

Pawhuska Pawhuska ( osa, 𐓄𐓘𐓢𐓶𐓮𐓤𐓘 / hpahúska, ''meaning: "White Hair"'', iow, Paháhga) is a city in and the county seat of Osage County, Oklahoma, United States. It was named after the 19th-century Osage chief, ''Paw-Hiu-Skah'', ...

. ''Sciroseps'' is thought to be related to a clade containing the extinct

Paramacellodidae Paramacellodidae is an extinct family of lizards that first appeared in the Middle Jurassic around 170 million years ago (Ma) and became extinct at the end of the Cretaceous around 66 Ma. It was one of the earliest groups of lizards to have under ...

and the extant

Cordylidae Cordylidae is a family of small- to medium-sized lizards that occur in southern and eastern Africa. They are commonly known as girdled lizards, spinytail lizards, or girdle-tail lizards. Cordylidae is closely related to the family Gerrhosauridae ...

. Suarez ''et al.'' list the defining

autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

for this taxon as a more gracile and convex dentary, less robust and shorter subdental laminae, dental coronae lacking lingual striae, overall more "gracile" dentition, subpleurodont tooth attachments, spatulate coronae, equal-in-length crista mesialis and crista distalis of posteriormost teeth, wider pars furcata, smaller crista intercuspidalis, "a more acutely pointed apex of the surangular notch, angular clasping of the surangular process of the dentary, coronoid process less exposed laterally between coronoid and surangular, tooth crowns more triangular, tooth crowns extending further beyond lateral parapet of dentary, and presence of well-defined inferior alveolar foramen in splenial," robust tooth shafts and widely spaced, taller, pointed coronae, lacking a distinct cusp of the angulis mesialis.

References

Scincomorpha Cretaceous lizards Late Cretaceous lepidosaurs Fossil taxa described in 2021 {{lizard-stub