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| Helioscopus dickersonae Meyer, Brownstein, Jenkins & Gauthier, 2023 |
Abstract
Geckos are a speciose and globally distributed clade of Squamata (lizards, including snakes and amphisbaenians) that are characterized by a host of modifications for nocturnal, scansorial and insectivorous ecologies. They are among the oldest divergences in the lizard crown, so understanding the origin of geckoes (Gekkota) is essential to understanding the origin of Squamata, the most species-rich extant tetrapod clade. However, the poor fossil record of gekkotans has obscured the sequence and timing of the assembly of their distinctive morphology. Here, we describe the first North American stem gekkotan based on a three-dimensionally preserved skull from the Morrison Formation of western North America. Despite its Late Jurassic age, the new species already possesses several key characteristics of the gekkotan skull along with retained ancestral features. We show that this new stem gekkotan, and several previously named species of uncertain phylogenetic relationships, comprise a widespread clade of early crown lizards, substantiating faunal homogeneity in Laurasia during the Late Jurassic that extended across disparate ecological, body-size and physiological classes.
Keywords: Squamata, Gekkota, phylogenetics, macroevolution, biogeography
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| CT Imagery of the skull of Helioscopus dickersonae (DINO 15914). (a, b) In situ skull in dorsal (a) and ventral (b) views. (c–f) Reconstructed skull in left lateral (c), right lateral (d), dorsal (e) and ventral (f) views. All scale bars 5 mm. bc, braincase; ‘cb’, fused postdentary elements (compound bone); d, dentary; f, frontal; j, jugal; m, maxilla; p, parietal; pa, palatine; pf, prefrontal; pof, postorbitofrontal; pt, pterygoid; sq, squamosal. |
Systematic paleontology
Squamata Oppel 1811 (sensu de Queiroz and Gauthier, 2020)
Pan-Gekkota Bauer 2020
†Ardeosauridae Camp 1923
†Helioscopus dickersonae gen. et sp. nov.
Etymology. Helioscopus, after the Ancient Greek helios (sun) and the Latinization of the Ancient Greek scopós (watcher) after the prominent pineal foramen found in this species, and dickersonae, the Latinized genitive form of ‘Dickerson’, in honour of Helen and Shirley Dickerson, the late grandmother and great aunt, respectively, of DM, as well as Mary Cynthia Dickerson, the first Curator of Herpetology and mentor to the celebrated lizard systematist Charles L. Camp, at the American Museum of Natural History.
Dalton Meyer, Chase D. Brownstein, Kelsey M. Jenkins and Jacques A. Gauthier. 2023. A Morrison Stem Gekkotan reveals Gecko Evolution and Jurassic Biogeography. Proc. R. Soc. B. 290; 2023228. DOI: 10.1098/rspb.2023.2284
phys.org/news/2023-11-gecko-ancestor-honor.html
