''Bellairsia'' is an extinct genus of

stem Stem or STEM most commonly refers to: * Plant stem, a structural axis of a vascular plant * Stem group * Science, technology, engineering, and mathematics Stem or STEM can also refer to: Language and writing * Word stem, part of a word respon ...

squamate Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest Order (biology), order of reptiles; most members of which are commonly known as Lizard, lizards, with the group also including Snake, snakes. With over 11,991 species, it i ...

known from a single species, ''Bellairsia gracilis'', from the

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...

(

Bathonian In the geologic timescale the Bathonian is an age (geology), age and stage (stratigraphy), stage of the Middle Jurassic. It lasted from approximately 168.2 ±1.2 annum, Ma to around 165.3 ±1.1 Ma (million years ago). The Bathonian Age succeeds ...

) of England and Scotland. It is amongst the oldest squamates known. It was originally described in 1998 by

Susan E. Evans Susan Elizabeth Evans is a British palaeontologist and herpetologist. She is the author or co-author of over 100 peer-reviewed papers and book chapters. She received a BSc in Zoology at Bedford College (London), Bedford College in 1974, and i ...

from disarticulated individual bones, including the holotype

dentary In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...

, collected from the

Forest Marble Formation The Forest Marble is a geological formation in England. Part of the Great Oolite Group, it dates to the late Bathonian stage of the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weisha ...

Kirtlington Quarry Kirtlington Quarry is a geological Site of Special Scientific Interest west of Kirtlington in Oxfordshire. It is a Geological Conservation Review site, and it is part of the Kirtlington Quarry Local Nature Reserve. Kirtlington Quarry is one of ...

, Oxfordshire, England. It was named in honor of British herpetologist and vertebrate anatomist

Angus Bellairs Angus d'Albini Bellairs (11 January 1918 – 26 September 1990) was a British professor of vertebrate morphology and a specialist in herpetology. He published a landmark two volume ''The Life of Reptiles'' (1970). Bellairs studied at Stowe School ...

. In 2022, a partial 70% complete skeleton was described from the equivalently aged

Kilmaluag Formation The Kilmaluag Formation is a Middle Jurassic geological formation in Scotland. It was formerly known as the Ostracod Limestone for preserving an abundance of fossil freshwater/low salinity ostracods. Gastropods, bivalves, trace fossil burrows, an ...

of the

Isle of Skye The Isle of Skye, or simply Skye, is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated by the Cuillin, the rocky slopes of which provide some of ...

, Scotland. The partial skeleton had an estimated snout-vent length of around . While originally considered a member of

Scincomorpha 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 ...

, the 2022 study recovered it to be a

stem-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

squamate, with the phylogeny recovering it as part of a weakly supported clade also containing ''

Huehuecuetzpalli ''Huehuecuetzpalli'' (translating to "the ancient lizard" in Nahuatl) is an extinct genus of lizard from the Early Cretaceous (late Albian) Tlayúa Formation, a Lagerstätte near Tepexi de Rodríguez, Central Mexico. One species, ''H. mixectus' ...

'' and '' Oculudentavis''.

Classification

Phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

after Talanda et al. (2022):

References

{{Taxonbar, from=Q110388030 Jurassic reptiles Middle Jurassic reptiles of Europe Jurassic England Fossils of England Fossil taxa described in 1998 Squamata Fossils of Scotland Jurassic Scotland Prehistoric reptile genera