 The late Permian and early Triassic concostricans from the baby I. Cayman section, western Siberia, were studied. Five late Permian concostrican species, Sudistheria novocostrinces, Mitchell, 1927, Cornia papylaria, Lutkovich, 1937, Megasitam harmonicum novogilove, 1970, Megasitam lapakulence novogilove, 1970, and Echinolum nadia metoxinovogilove, 1965, and two early Triassic species, Conturisma temensis novogilove, 1958, Cyquitungusites gutta, Lutkovich, 1938, were identified. These concostrican species are common in the Permian and Triassic sections of other regions, and can be used to establish regional biostratigraphy and interregional correlation. This article was authored by six Davidov, V. V. Zaranova, and V. V. Silenteev.