A new relict stem salamander from the Early Cretaceous of Yakutia, Siberian Russia

Skutschas, Pavel P.; Kolchanov, Veniamin V.; Averianov, Alexander O.; Martin, Thomas; Schellhorn, Rico; Kolosov, P. N.; Vitenko, Dmitry D.

doi:10.4202/app.00498.2018

Cited by 19 publications

(18 citation statements)

References 12 publications

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“…This team screen‐washed 500 kg of matrix in 2017 and 675 kg in 2018. Numerous vertebrate microfossils were discovered, including remains of fishes, salamanders, turtles, choristoderes, lizards, dinosaurs, tritylodontids and mammals (Skutschas et al ; Averianov et al, 2018a).…”

Section: Methodsmentioning

confidence: 99%

“…The Teete vertebrate assemblage comprises both endothermic, or presumably endothermic tetrapods (theropod dinosaurs, tritylodontids and mammals), and ectothermic tetrapods (salamanders, turtles, choristoderes and lizards) (Averianov et al 2018a; Skutschas et al ). Remains of turtles are rare, which markedly contrast, with more southern Mesozoic vertebrate assemblages, where turtles are usually the dominant tetrapods.…”

Section: Methodsmentioning

confidence: 99%

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The northernmost sauropod record in the Northern Hemisphere

Averianov

Skutschas

Schellhorn

et al. 2020

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Isolated sauropod teeth from the Early Cretaceous Teete locality in Yakutia (Eastern Siberia, Russia) are the only evidence that sauropods lived in high latitudes (palaeolatitude estimate of N 62°) in the Northern Hemisphere. The spatulate broad tooth crowns of adult individuals lack marginal denticles while these are present in a juvenile tooth. The teeth have overlapping facets and likely belong to a basal macronarian. The juvenile tooth indicates that sauropods reproduced in high latitudes and possibly stayed there around the year. The Teete vertebrate assemblage comprises both endothermic, or presumably endothermic tetrapods (theropod dinosaurs, tritylodontids and mammals), and ectothermic tetrapods (salamanders, turtles, choristoderes and lizards), but no crocodyliforms. This suggests a temperate climate, with an annual mean temperature well above freezing level but below 14°C.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The northernmost sauropod record in the Northern Hemisphere

Averianov

Skutschas

Schellhorn

et al. 2020

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“…All these characters are primitive for crown salamanders and characteristic for stem group salamanders (e.g. [7,14]).…”

Section: Discussionmentioning

confidence: 99%

“…Referred to stem group salamanders based on the absence of spinal nerve foramina in the atlas, the presence of an anteroposteriorly short atlantal neural arch with an anterior border that is situated posteriorly from the level of the anterior cotyles, the presence of a pitted texture on the ventral and lateral surfaces of the atlas and trunk vertebrae. Differs from all other stem salamanders for which the morphology of the atlantal vertebral centrum is known (namely Urupia from the Berezovsk Quarry locality [8], Kokartus from the Middle Jurassic (Bathonian) of Kyrgyzstan [4,13], Marmorerpeton from the Middle Jurassic (Bathonian) of United Kingdom [3], and Kulgeriherpeton the Early Cretaceous (Berriasian-Barremian) of Russia [14]) by a relatively wider posterior portion of the atlantal centrum (ratio of maximal anterior width/maximal posterior width about 1.9 vs. Additionally, Egoria gen. nov. differs from Urupia by the lack of pronounced ventro-lateral ridges on the atlas, and by less dorso-ventrally compressed atlantal anterior cotyles (ratio of maximum height/width about 0.8 vs. about 0.5 in Urupia); from Marmorerpeton in the presence of atlantal transverse processes; and from Kulgeriherpeton by the lack of a transversal ridge and a depression on the ventral surface of the posterior portion of the centrum. Differs from all other stem salamanders for which the morphology of the trunk vertebral centra is known (namely Urupia, Kokartus, Marmorerpeton, and Kulgeriherpeton) in having the upper transverse process (= diapophysis) remarkably larger than the lower transverse process (= parapophysis); from Urupia, Kokartus, and Kulgeriherpeton in anteroposteriorly short trunk vertebral centra (ratio of ventral midline length: maximum centrum width about 1.2-1.3 vs. 1.4 in Urupia, 1.5-1.6 in Kokartus and 1.6 in Kulgeriherpeton).…”

Section: Systematic Paleontologymentioning

confidence: 99%

A new small-sized stem salamander from the Middle Jurassic of Western Siberia, Russia

et al. 2020

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Salamanders (Caudata) are one of the three modern groups of amphibians known from the Middle Jurassic. The early stages of evolution of these amphibians are still poorly known, especially for stem taxa of Jurassic age. A new small-sized stem salamander, Egoria malashichevi gen. et sp. nov., from the Middle Jurassic (Bathonian) Itat Formation of the Berezovsk Quarry locality in Western Siberia, Russia, is described on the basis of isolated vertebrae, including an atlas centrum and a fragmentary trunk vertebra centrum previously referred to an undescribed salamander taxon ("Berezovsk salamander A"). The new taxon is diagnosed by the following unique combination of vertebral characters: atlantal anterior cotyles with elliptical anterior outline, located at an angle of approximately 135-137 degrees to each other; wide posterior portion of the atlantal centrum; ossified portion of the intercotylar tubercle represented by dorsal and ventral lips; absence of a deep depression on the ventral surface of the atlantal centrum; absence of pronounced ventrolateral ridges on the atlas; absence of spinal nerve foramina; presence of a pitted texture on the ventral and lateral surfaces of the centra and lateral surfaces neural arch pedicels; presence of a short atlantal neural arch with its anterior border situated behind the level of the anterior cotyles; short trunk vertebrae; and upper transverse process (= diapophysis) larger than lower transverse process (= parapophysis) on the trunk vertebrae; notochordal canal opens in the upper half of the cotyle (= the lower portion of the centrum is more massive and less compact than the upper portion). The microanatomical organization of the atlas and trunk vertebrae is characterized by the presence of inner cancellous endochondral bone. The small body size (about 180-215 mm) of Egoria malashichevi gen. et sp. nov. indicates that that not all stem salamanders were large neotenic forms (up to 550-600 mm in Urupia and Marmorerpeton) and hints at a broader ecological role for stem salamanders.

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“…The Early Cretaceous (Berriasian-Barremian) Teete vertebrate assemblage in southwestern Yakutia (Eastern Siberia, Russia) was formed close to Mesozoic polar latitudes (paleolatitude estimate of N 62˚in Averianov et al, 2019 and N 66.5˚in Fossilworks, http://fossilworks.org.) and is widely known for its polar dinosaurs, as well as turtles, salamanders, and mammaliaforms and mammals [7][8][9][10][11][12][13][14]. The high-latitude dinosaurian assemblage of Teete includes stegosaurs, ornithopods, theropods, and sauropods [9,10].…”

Section: Introductionmentioning

confidence: 99%

Wear patterns and dental functioning in an Early Cretaceous stegosaur from Yakutia, Eastern Russia

et al. 2021

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Isolated stegosaurian teeth from the Early Cretaceous high-latitude (palaeolatitude estimate of N 62°- 66.5°) Teete locality in Yakutia (Eastern Siberia, Russia) are characterized by a labiolingually compressed, slightly asymmetrical and mesiodistally denticulated (9–14 denticles) crown, a pronounced ring-like cingulum, as well as a “complex network of secondary ridges”. The 63 teeth (found during on-site excavation in 2012, 2017–2019 and screen-washing in 2017–2019) most likely belong to one species of a derived (stegosaurine) stegosaur. Most of the teeth exhibit a high degree of wear and up to three wear facets has been observed on a single tooth. The prevalence of worn teeth with up to three wear facets and the presence of different types of facets (including steeply inclined and groove-like) indicate the tooth-tooth contact and precise dental occlusion in the Teete stegosaur. The microwear pattern (mesiodistally or slightly obliquely oriented scratches; differently oriented straight and curved scratches on some wear facets) suggest a complex jaw mechanism with palinal jaw motion. Histological analysis revealed that the Teete stegosaur is characterized by relatively short tooth formation time (95 days) and the presence of a “wavy enamel pattern”. Discoveries of a “wavy enamel pattern” in the Teete stegosaur, in a Middle Jurassic stegosaur from Western Siberia, and in the basal ceratopsian Psittacosaurus, suggest that this histological feature is common for different ornithischian clades, including ornithopods, marginocephalians, and thyreophorans. A juvenile tooth in the Teete sample indicates that stegosaurs were year-round residents and reproduced in high latitudes. The combination of high degree of tooth wear with formation of multiple wear facets, complex jaw motions, relatively short tooth formation time and possibly high tooth replacement rates is interpreted as a special adaptation for a life in high-latitude conditions or, alternatively, as a common stegosaurian adaptation making stegosaurs a successful group of herbivorous dinosaurs in the Middle Jurassic–Early Cretaceous and enabeling them to live in both low- and high-latitude ecosystems.

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A new relict stem salamander from the Early Cretaceous of Yakutia, Siberian Russia

Abstract: A new stem salamander, Kulgeriherpeton ultimum gen. et sp. nov., is described based on a nearly complete atlas (holotype) from the Lower Cretaceous (Berriasian-Barremian) Teete vertebrate locality in southwestern Yakutia (Eastern Siberia, Russia

Cited by 19 publications

References 12 publications

The northernmost sauropod record in the Northern Hemisphere

The northernmost sauropod record in the Northern Hemisphere

A new small-sized stem salamander from the Middle Jurassic of Western Siberia, Russia

Wear patterns and dental functioning in an Early Cretaceous stegosaur from Yakutia, Eastern Russia

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