The Key to Understanding the European Miocene Chalcides (Squamata, Scincidae) Comes from Asia: The Lizards of the East Siberian Tagay Locality (Baikal Lake) in Russia

Abstract

The early middle Miocene (MN 5) lizards from the East Siberian Tagay locality (Baikal Lake, Russia) in Asia are described here. The lizard fauna consists of two clades, Lacertidae and Scincidae. The skink material is allocated to Chalcides. While this taxon was previously reported from Europe, it has rarely been observed in the Neogene record with only jaw fragments and frontal bones described. Its taxonomy was therefore enigmatic. The Tagay material is almost identical to the European fossils of Chalcides from Austria and Hungary, but it also contains the parietal bone. While the material is also similar to the extant Ch. ocellatus, it exhibits several morphological differences. A new species is therefore erected—Chalcides augei sp. nov. These findings further support the connection of the Baikal Lake area with central Europe during the first half of the Miocene. The comparative anatomy of the frontals, parietals and lower jaws was evaluated by micro‐CT in selected skink taxa. This comparison highlights several important differences, for example, paired frontals are present in Broadleysaurus (an outgroup taxon), in Acontias and all studied members of Scincidae herein. The character optimization in Mesquite supports fused frontals as being the condition at the basal node of the Ateuchosauridae + Sphenomorphidae + Eugongylidae + Lygosomidae + Egerniidae + Mabuyidae clade. While the parapineal foramen is restricted to the parietal in most taxa studied herein, it is absent (or vestigial) in Acontias and Feylinia. In contrast to all other skinks, this foramen is located on the frontal in Ateuchosaurus chinensis. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:1901–1934, 2020. © 2019 American Association for Anatomy

The Miocene fossil lizards from Kutch (Gujarat), India: a rare window to the past diversity of this subcontinent

“…Among skinks, the closed Meckelian canal in the dentary can be observed in several lineages (Greer, 1970(Greer, , 1974Estes et al, 1988;Shea, 1999;Caputo, 2004;Hutchinson and Scanlon, 2009;Bolet et al, 2015;C ̌erňanský et al, 2020b;C ̌erňanský and Syromyatnikova, 2021) 5) tooth crown morphology. One member of the mabuyines, Eutropis, occurs in the Territory of India (Mausfeld et al, 2002), but note that one taxon from Indochina, Toenayar novemcarinata (Anderson, 1871), has been separated from Eutropis and placed in the monotypic genus Toenayar (Karin et al, 2016).…”

“…Among skinks, the closed Meckelian canal in the dentary can be observed in several lineages (Greer, 1970, 1974; Estes et al, 1988; Shea, 1999; Caputo, 2004; Hutchinson and Scanlon, 2009; Bolet et al, 2015; Čerňanský et al, 2020b; Čerňanský and Syromyatnikova, 2021): Mabuyinae, Egerniinae, Eugongylinae, Sphenomorphinae, Lygosominae, but also in Acontinae, whereas Scincinae and Ateuchosaurus have a fully open canal. The preserved morphology of the Tapar dentaries most resembles that of members of the clade Mabuyinae in the combination of the following features (Čerňanský et al, 2020b; Čerňanský and Syromyatnikova, 2021): (1) the closed Meckelian canal; (2) narrow ventral section under the dental portion relative to high alveolar crest; (3) close tooth spacing, including the level of the crowns; and (5) tooth crown morphology. One member of the mabuyines, Eutropis , occurs in the Territory of India (Mausfeld et al, 2002), but note that one taxon from Indochina, Toenayar novemcarinata (Anderson, 1871), has been separated from Eutropis and placed in the monotypic genus Toenayar (Karin et al, 2016).…”

Nomenclature of supra-generic units within the Family Scincidae (Squamata)

“…I have been able to identify 12 uses of Eugongylidae (Hedges & Conn 2012;Zug 2013;Hedges 2014;W. Schmidt 2014;Bahmani et al 2016Bahmani et al , 2018Jablonski 2016;Lorvelec et al 2017;Paluh & Bauer 2017;Čerňaňský et al 2020;Speybroeck et al 2020;Čerňaňský & Syromyatnikova 2021), 27 uses of Eugongylinae (Safaei-Mahroo et al 2015;Čerňaňský 2016;Chapple 2016a,b;Gartrell 2016;Hitchmough et al 2016;Lettinck & Hare 2016;Medina et al 2016;Worthy 2016;Eftekharian et al 2017;Worthy et al 2017;Caldwell et al 2018;Foster et al 2018;Rahnama & Jojati 2018;Ortiz et al 2019;Thorn et al 2019Thorn et al , 2021Weinell et al 2019;Bozkurt & Olgun 2020;Hare et al 2020;Bernstein et al 2021;Chapple et al 2021;L. Chen et al 2021;O'Shea 2021;Patterson & Hitchmough 2021) and three uses of Eugongylini (Greer 2001(Greer , 2002Batuwita 2019).…”

“…The Egerniini of Welch (1982), and the earlier Egernina of De Vis (1888), which need to be treated as independent due to the different stems employed in the formation of the names, apply to a much more geographically restricted (Australia, the Solomon Islands, New Guinea and the Maluku Archipelago of Indonesia) and less species-rich (62 species in 8 genera) lineage for which there have been many fewer uses of the terms Egerniini/Egerninae/Egernidae (although again the informal name Egernia group of Greer (1979) has a much greater usage). While I have been able to identify 40 uses of these names (with or without the double -i) since Welch (1982) created Egerniini (Egerniidae: Hedges & Conn 2012;Pyron et al 2013;Zug 2013;Hedges 2014;Sy 2015;Bahmani et al 2016Bahmani et al , 2018Feizi et al 2016;Paluh & Bauer 2017;Čerňaňský et al 2020;Čerňaňský & Syromyatnikova 2021;Egerniinae: Hitchmough et al 2016;Bull et al 2017;Halliwell et al 2017a-c;Atkins et al 2018Atkins et al , 2020Foster et al 2018;Norval et al 2018Norval et al , 2021Bower et al 2019;Chapple et al 2019Chapple et al , 2021Ortiz et al 2019;Thorn et al 2019Thorn et al , 2021Treilibs et al 2019;While et al 2019;Norval & Gardner 2020;Pearson et al 2020;Ridley et al 2020;Stampe et al 2020;Thompson et al 2020;Watson et al 2020…”

Geology and lithology of the Tagay-1 section at Olkhon Island (Lake Baikal, Eastern Siberia), and description of Aplodontidae, Mylagaulidae and Sciuridae (Rodentia, Mammalia)

“…Syromyatnikova, A.S.Tesakov and A.M. Klementiev), rich fossil material was collected from the Tagay locality in the 2000s. Numerous articles on the fauna, geology and taphonomy of the Tagay locality were published, others are to be expected (Čerňanský et al 2020 ; Klementiev and Sizov 2015 ; Sizov and Klementiev 2015 ; Sotnikova et al 2019 ; Syromyatnikova 2014 , 2015 , 2016 ; Tesakov et al 2014 ; Tesakov and Lopatin 2015 ; Volkova 2020 ; Zelenkov 2015 , 2016 , 2018 ).

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