Article: Early Ordovician trilobites from Dali, west Yunnan, China, and their palaeogeographical significance
Eleven late Arenig—Llanvirn trilobite taxa, including one new species, Neseuretus elongatus, are described from the Hsiangyang Formation east of Dali, in the eastern part of west Yunnan, China, an area that may have been part of the Indo-China Terrane. The trilobites are mostly typical representatives of Gondwana cold-water faunas, and their close biogeographical relationships with south-central Europe and the Yangtze region are discussed. Four biofacies are differentiated in relation to an environmental gradient: Cruziana Biofacies (intertidal); Neseuretus Biofacies (inner shelf); Trinucleid Biofacies (shallow outer shelf); and Cyclopygid Biofacies (deep outer shelf). The rocks of the Hsiangyang Formation are interpreted as a deepening-upwards sequence.