Two Pleistocene sections in the middle reaches of the Volga River – Spasskoe and Yagodnoe – have been described in details and analyzed, small mammal remains being recovered and identified. The fauna includes remains of open landscape species: Eolagurus luteus (Eremin and Moloskovsky, 1981), Lagurus lagurus Pallas, 1773, Lasiopodomys (Stenocranius) gregalis (Pallas, 1779) and others. Bone remains of a tundra species – collared lemming Dicrostonyx sp. were found in the Spasskoe section. No forest species are present in the sequence, nor remains of water vole Arvicola. The species richness of the faunas is rather low, which may be related to insufficient amount of material or to a specific climate. Such low species richness is typical of the periglacial faunas of the Pleistocene. The authors of recent article attribute the third Volga terrace to the Late Pleistocene refer usually to the 3rd terrace deposits in the lower reaches of the Volga where the Caspian Upper Khazarian (Hyrcanian) layers are found at the base of the sequence. The rodent molar morphology permits to date fauna to the beginning of the Late Pleistocene (to the early stages of the Valday glaciation) and to reconstruct periglacial steppes widely distributed in the Volga middle reaches at that time.

伏尔加河中游的两个更新世部分——Spasskoe 和 Yagodnoe——已被详细描述和分析，小型哺乳动物遗骸正在被恢复和识别。动物群包括开放景观物种的遗骸：Eolagurus luteus（Eremin 和 Moloskovsky，1981）、Lagurus lagurus Pallas，1773、Lasiopodomys（Stenocranius）gregalis（Pallas，1779）等。苔原物种的骨骼遗骸 - 领旅鼠Dicrostonyx sp。在斯帕斯科部分被发现。序列中不存在森林物种，也没有水田鼠Arvicola 的遗骸. 动物群的物种丰富度较低，这可能与物质数量不足或特定气候有关。如此低的物种丰富度是更新世冰缘动物群的典型特征。最近文章的作者将第三伏尔加阶地归因于晚更新世，通常指伏尔加河下游的第三阶地沉积物，在该层序底部发现里海上可萨（Hyrcanian）层。啮齿动物的臼齿形态允许将动物群追溯到晚更新世开始（到瓦尔代冰川的早期阶段），并重建当时广泛分布在伏尔加河中游的冰缘草原。