Oculudentavis Xing et al.

Bolet, Arnau, Stanley, Edward L., Daza, Juan D., Arias, J. Salvador, Cernanský, Andrej, Vidal-García, Marta, Bauer, Aaron M., Bevitt, Joseph J., Peretti, Adolf & Evans, Susan E., 2021, Unusual morphology in the mid-Cretaceous lizard Oculudentavis, Current Biology 31, pp. 1-12 : 2-4

Genus Oculudentavis Xing et al. 1

Type species Oculudentavis khaungraae Xing et al. 1

Note: The retraction 8 of the original description of this taxon 1 does not affect the nomenclatural availability of Oculudentavis khaungraae under the International Code of Zoological Nomenclature (chapters 3 and 4), as retraction of a paper by itself has no nomenclatural consequence. 9–11 Using O. khaungraae as an example, there have been recommendations that the code needs to be modified to cover names and nomenclatural acts contained in retracted papers and to include a rule that can be applied automatically without the necessity of submitting a case. 12 Nonetheless, at the present time, the current regulations stand.

Diagnosis of the genus Oculudentavis

Oculudentavis can be identified as a lizard by having a pleurodont dentition with posterolingual tooth replacement, a short quadrate with a lateral conch, a streptostylic quadrate suspension, a ‘‘hockey stick’’-shaped squamosal, a reduced quadrate-pterygoid contact, an enclosed vidian canal (posterior opening within the basisphenoid), a prootic with an alar process and a prominent crista prootica, and a braincase in which the metotic fissure is subdivided into a small ovoid lateral opening of the recessus scalae tympani and a posterior vagus foramen (differentiating it from archosaurs, where the metotic fissure becomes enclosed, following a totally different development). 13 The genus Oculudentavis can be diagnosed by the following apomorphic characters. Some of these characters are reworded here from the original diagnosis of O. khaungraae 1 and some from a subsequent paper, 3 which now includes characters that only apply to O. khaungraae : jugal expanded horizontally creating a wide ventral orbital flange; jugal bar cross-section strongly angled dorsolaterally-ventromedially; 1 22 to 23 teeth in maxilla, about four of which are located beneath the orbit; vomers contact both the premaxillary and maxillary shelves; large unpaired median premaxilla with a long dorsal crest along nasal process that is continued onto the dorsal surface of the nasals along most of its length; premaxilla replaces maxilla in anterolateral part of rostrum; ring-shaped lacrimal fully enclosing large lacrimal foramen; short vaulted parietals partially fused; and presence of a flat surface (forming a platform) on the dorsolabial side of the posterior third of the dentary.

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Oculudentavis differs from all other known lizards in possessing the following unique combination of characters: premaxilla forming exclusively the tip of the rostrum and the anterolateral border of the nares; elongated paired nasals that slot into a triangular frontal recess; no parietal foramen, supratemporal processes angled vertically downward; strongly triradiate postorbital with long squamosal process reaching posterior margin of parietal; very large suborbital fenestra; palatal dentition on the pterygoids—differing from the interpretation in Li et al., 3 which also reported teeth on the palatine, the presence of which we have been unable to confirm; in dentary, dorsal and ventral margins of the Meckelian fossa meet to close fossa, but do not fuse; and short postdentary region with coronoid bearing a low, posteriorly set process, short deep adductor fossa, and long slender retroarticular process.

Oculudentavis further differs from all squamates except Huehuecuetzpalli in having a long tapering rostrum 3 composed of premaxilla, maxillae, and elongated paired nasals that slot into a triangular frontalrecess; from allsquamates except for Huehuecuetzpalli , varanids, lanthanotids, monstersaurs, and mosasaurs in theretractednarial openings, 3 although inallbut Huehuecuetzpalli a reduction of the nasals occurs; from all squamates except chameleons in having a prefrontal with an anterolateral shelf (‘‘boss’’ in Gauthier et al. 7) that overhangs maxilla and lacrimal; from all squamates except for the pygopodid Lialis in its very long slender mandible composed mainly of shallow elongate dentary and relatively short post-dentary portion; and from all squamates except for some anguimorphs in the presence of posterolingual tooth replacement. The closed (but not fused) Meckelian fossa is shared mainly with iguanians, differing from the open fossa of most anguimorphs, lacertoids, and scincoids and the closed and fused fossa of gekkotans, dibamids, gymnophthalmids, xantusiids, some scincids, and some iguanians.

Thepremaxilla,maxilla,andnasalare notfusedinto asingle unit as was described in the original description of O. khaungraae . 1