A natural assemblage of Ellisonia sp. cf. E. triassica Müller (Vertebrata: Conodonta) from the uppermost Permian in the Suzuka Mountains, central Japan

Abstract

A natural assemblage of Ellisonia sp. cf. E. triassica Müller was recovered from the uppermost Permian close to the Permian-Triassic boundary in the Nabejiriyama section in the Mt. Ryozen area, Suzuka Mountains, central Japan. This natural assemblage and collections of similar ellisonids from the Taho Formation of Ehime Prefecture, southwestern Japan, demonstrate that the Ellisonia apparatus is composed of eight kinds of elements: breviform digyrate M, symmetrical S0, extensiform digyrate S1 and S2, bipennate S3 and S4, and angulate P1 and P2 elements. The apparatus structure of Ellisonia is comparable to the standard 15-element plan of Carboniferous ozarkodinids and prioniodinids. The apparatus structure of the present natural assemblage is important in discussing the phylogenetic affinity of the genus Ellisonia. © by the Palaeontological Society of Japan.