Mesozoic salamanders and albanerpetontids of Middle Asia, Kazakhstan, and Siberia

Abstract

Mesozoic terrestrial deposits containing diverse vertebrate assemblages are widely distributed in Siberia (central and eastern part of Russia), Middle Asia (Kyrgyzstan, Tajikistan, Turkmenistan and Uzbekistan), and Kazakhstan. Twelve formations of Middle Jurassic (Bathonian) to Late Cretaceous (Campanian) age in the region contain salamanders (six in Middle Asia, two in Siberia and four in Kazakhstan). In contrast to the situation in Euramerica, albanerpetontids are extremely rare in the Mesozoic of Asia, where their fossil record is limited to the Khodzhakul (Cenomanian) and Bissekty (Turonian) formations, both in Uzbekistan. Salamanders in Siberia are known from the Bathonian Itat Formation in the Krasnoyarsk Region (the stem salamander Urupia monstrosa and two undescribed taxa—a new stem salamander and a possible crown-group salamander) and from the Aptian–Albian Ilek Formation in Kemerovo Province and the Krasnoyarsk Region (the crown-group salamander Kiyatriton leshchinskiyi and Caudata indet.). In the Jurassic of Middle Asia, the stem salamanders Kokartus honorarius and Karauridae indet. are known from the Bathonian–Callovian Balabansai Formation in Kyrgyzstan. Younger records in Middle Asia are restricted to only two Late Cretaceous genera of crown-group salamanders: the possible cryptobranchoid Nesovtriton in the Bissekty Formation (Turonian) and the cryptobranchid Eoscapherpeton in the Khodzhakul, Dzharakuduk, Bissekty, and Aitym formations (collectively Cenomanian–Campanian) in Uzbekistan and the Yalovach Formation (Santonian) in Tajikistan. In Kazakhstan, salamanders are known from the Kimmeridgian Karabastau Formation (the stem salamander Karaurus sharovi), the Turonian Zhirkindek Formation (Caudata indet.), the Santonian–Campanian Bostobe Formation (the cryptobranchid Eoscapherpeton, the possible proteid “Bishara backa” and Caudata indet.) and the Campanian Darbasa Formation (the cryptobranchid Eoscapherpeton). Cenomanian–Campanian vertebrate assemblages in Middle Asia and Kazakhstan are characterised by dominance of the cryptobranchid Eoscapherpeton.