This article deals with a unique discovery. In 2010, a school expedition found an obscure skull of a woolly rhinoceros on Mamontova Mountain in the Republic of Sakha (Yakutia). Young paleontologists with their leader P. D. Maksimov conducted an anatomical study of the woolly rhinoceros' fossil skull. During the entire period (years 1973–2021) of the camp's existence, young paleontologists have found the remains of 57 animal fossils. All the materials found during the expeditions have been stored in the museum-laboratory at the Republican Ecological-Paleontological Camp of Schoolchildren “Tusk.” Among the gathered paleontological finds, the young researchers were attracted to rhinoceros skulls found at different times near various excavations. The expedition participants have put forward the hypothesis that during the period of the flourishing of the mammoth fauna, there might have been some species or subspecies of woolly rhinoceros on the territory of Paleoyakutia besides the Lena species. The results of the research were highly appreciated by the experts of the republican scientific conferences.