A new borioteiioid lizard with large caniniform tooth from the Upper Cretaceous of South China

Borioteiioidea (Polyglyphanodontia) is a group of lizards that were abundant in China and Mongolia during the Late Cretaceous. Two borioteiioid genera, <i>Tianyusaurus</i> and <i>Yechilacerta</i>, with complete lower temporal bars, have been reported from the Upper Cretaceous of South China. Here we report a new borioteiioid fossil lizard, <i>Caninosaurus ganzhouensis</i> gen. et sp. nov., based on an incomplete skull and mandible from the Upper Cretaceous Tangbian Formation of Ganzhou Basin, Jiangxi Province, South China. The new lizard differs from other Late Cretaceous lizards by possessing a unique combination of features, including nasal process of the premaxilla constricted at the base; elongated posterodorsal projection of the maxillary facial process; no articulation between the nasal and prefrontal; a prefrontal with a fossa on its lateral surface; elongated frontals with sculptured dorsal surface and a waisted orbital margin; tooth crowns with no denticles and cusps; and a large and caniniform fourth maxillary tooth. Phylogenetic analyses based on two recent data matrices both recover <i>Caninosaurus</i> within Borioteiioidea. In the unconstrained analyses, <i>Caninosaurus</i> is placed in a clade with <i>Tianyusaurus</i> and <i>Yechilacerta. Caninosaurus</i> is the third borioteiioid lizard discovered from the Upper Cretaceous of the Jiangxi Province, increasing the diversity of borioteiioid lizards found in eastern Asia. The small body size and possible omnivorous diet of <i>Caninosaurus</i> suggest it occupied a different ecological niche to <i>Tianyusaurus</i> and <i>Yechilacerta</i>. https://zoobank.org/urn:lsid:zoobank.org:pub:3F0B9E9D-E1FC-407D-8126-8ABBF63F8437