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First Record of a Cryptonellid Brachiopod ? Heterelasma sp. in the Lower Triassic of Southern Primorye, Russia

  • A. M. Popov

摘要

Abstract

One specimen was discovered, possibly of a cryptonellid brachiopod of the genus Heterelasma Girty, 1909 in 2013, in Southern Primorye (Kamenushka River basin) in the sediments of the Neocolumbites insignis Zone of the Lower Triassic Upper Olenekian Substage. Fieldwork at the same section in 2023 aiming to collect additional materials of brachiopods was unsuccessful, so the previously made find is so far unique. Seventeen species of the genus Heterelasma have been described, exclusively from the Permian deposits in the USA, Mexico, South China, Nepal and Pakistan. The single specimen of a cryptonellid brachiopod is morphologically identical to previously described species of the genus Heterelasma, which suggests that this genus survived the Permian-Triassic global extinction, and the available material most likely represents a new species of this genus. As the shell is incompletely preserved and the shell interior cannot be fully characterized, the description of this rare for Triassic deposits find is given in open nomenclature. Redeposition of this specimen can be ruled out, because the host sedimentary rocks contain fossils in the undisturbed Lower Triassic sequence.