Discovery of scyphocrinoid loboliths in western Junggar, Xinjiang, NW China: Implications for scyphocrinoid paleobiogeography and identification of the Silurian–Devonian boundary

Abstract

The loboliths, which previously have been called “plurilocular cystoids” in China, are actually the bulbous roots of scyphocrinoids, which occur only, and are widely distributed, in the uppermost Silurian through the lowermost Devonian. Two quite different types of loboliths can be distinguished, the plate- and cirrus-types loboliths, both of which are significant fossils for the correlation of the strata at the Silurian–Devonian boundary. Two lobolith-bearing layers were found in pyroclastic turbidites at the Silurian–Devonian transition in western Junggar, Xinjiang, NW China; all identified loboliths are of the plate type. This discovery provides not only important information for determination of the Silurian–Devonian boundary in western Junggar, but also for the stratigraphic correlation outside of peri-Gongwana and Laurussia. Moreover, the finds are expanding the knowledge of the paleogeographic distribution of scyphocrinoids across facies boundaries between the paleocontinents.