Re-evaluation of Mynbulakia Nesov, 1981 (Lissamphibia: Caudata) and description of a new salamander genus from the Late Cretaceous of Uzbekistan

ABSTRACT

Isolated skull and postcranial bones previously assigned to the monotypic batrachosauroidid salamander genus Mynbulakia Nesov, 1981 (Uzbekistan, Byssekty Formation, Turonian) are re-interpreted as a mixture of two salamander taxa. The holotype maxilla of Mynbulakia surgayi Nesov, 1981, and dentaries, parietals, and femora previously referred to that species belong to smaller and, presumably, younger individuals of the cryptobranchid Eoscapherpeton asiaticum Nesov, 1981. Atlantes and trunk vertebrae previously referred to M. surgayi, along with additional vertebrae collected more recently from the Byssekty Formation, belong to Nesovtriton mynbulakensis gen. et sp. nov.. The structure of the atlas, the absence of spinal nerve foramina in the trunk and anterior caudal vertebrae, and the presence of unicipital transverse processes on the trunk vertebrae suggest that N. mynbulakensis may be a member of the Cryptobranchoidea. Two salamander taxa (E. asiaticum and N. mynbulakensis) are currently known from the Bissekty Formation and no salamander families are shared between the Late Cretaceous tetrapod assemblages of Asia and Euramerica.