A tritylodontid synapsid from the Middle Jurassic of Siberia and the taxonomy of derived tritylodontids

The last ceratosaur of Asia: a new noasaurid from the Early Cretaceous Great Siberian Refugium

“…This taxon is about 40 Myr younger than the previous youngest record of ceratosaurs in Asia [5]. The new noasaurid was part of an unusual vertebrate assemblage, dominated by an advanced ceratopsian dinosaur Psittacosaurus sibiricus [6,7], but also containing groups of tetrapods that have long since gone extinct in other regions, like stem salamanders, protosuchian and shartegosuchid crocodyliforms, tritylodontid synapsids and docodontan mammaliaforms [8][9][10].…”

“…This diverse assemblage includes, among other groups, stem karaurid salamanders, crown salamander Kiyatriton, basal choristoderes, tritylodontid synapsid Stereognathus, stegosaurs, docodontans and euharamyidans. All these taxa, even the genera Kiyatriton and Stereognathus, are found also in the 50 Myr younger Aptian Ilek Formation distributed in the same area, Krasnoyarsk krai and Kemerovo oblast [8][9][10]65,66]. Among the novel taxa of the Ilek Formation there are some typical Early Cretaceous groups such as dsungaripterid pterosaurs [67], titanosaurian sauropods [68,69] and basal ceratopsian Psittacosaurus [6,7].…”

Mammalian petrosal from the Lower Cretaceous high paleo-latitude Teete locality (Yakutia, Eastern Russia)

“…Remains of several mammaliamorphs have been reported for the Teete locality so far, including the tritylo dontid Stereognathus kolossovi, the euharamiyi dan Cryo haramiya tarda, the tegotheriid docodontan Khoro the rium yakutense, and the eutriconodontan Sanga rothe rium aquilonium (Lopatin and Agadjanian 2008;Averianov et al 2017Averianov et al , 2018Averianov et al , 2019, and a yet undescribed gobiconodontid.…”

“…The non-mammaliamorph vertebrates comprise dinosaurs, turtles, lizards, choristoderes, and salamanders (Skutschas et al 2018(Skutschas et al , 2020(Skutschas et al , 2021Averianov et al 2020). Mammaliamorphs are represented by the tritylodontid Stereognathus kolossovi, the euharamiyidan Cryoharamiya tarda, the tegotheriid docodontan Khorotherium yakutense (corrected here from K. yakutensis Averianov et al 2018 to neuter gender K. yakutense), the eutriconodontan Sangarotherium aquilonium (Lopatin and Agadjanian 2008;Averianov et al 2017Averianov et al , 2018Averianov et al , 2019, and a yet undescribed gobiconodontid. Three joint Russian-German field seasons (2017)(2018)(2019) focused on screen washing of fossiliferous matrix which yielded numerous micro-vertebrate remains including a mammalian petrosal from the Teete locality.…”