(Lagomorpha, Mammalia) from the Tagay locality (Olkhon Island, Baikal region, Eastern Siberia).

Unlabelled: New excavations in the Tagay locality have revealed the presence of Erbajeva, 2013, which belongs to the palaeolagine Lagomorpha rather than leporids, previously referred to sp. (Logachev et al., 1964). Herein, we report a comprehensive morphological description of this species and compare it with the other known species of the genus . The Tagay lagomorph is conspecific with the Early Miocene species found at locality Unkheltseg (UNCH-A) (biozone D; Early Miocene) in the Valley of Lakes, Central Mongolia. The Tagay specimens suggest a more advanced evolutionary stage of and an age around Early/Middle Miocene transition.

Supplementary Information: The online version contains supplementary material available at 10.1007/s12549-022-00554-y.