Two early millericrinids and an unusual crinoid of uncertain systematic position from the lower Upper Anisian (Middle Triassic) of Qingyan, southwestern China

Abstract

Well-preserved stem remains of the three crinoid species Qingyanocrinus kueichounensis (Dubatolova and Shao, 1959), Bangtoupocrinus kokeni n. gen. n. sp. and Silesiacrinus parvus n. sp. from the lower Upper Anisian (Middle Triassic) of Qingyan, Guizhou Province, southwestern China, are described. The former two taxa originally were described as one species, Entrochus rotiformis Koken, 1900, which is a nomen dubium. The two new genera Qingyanocrinus and Bangtoupocrinus are established. Bangtoupocrinus and Silesiacrinus are the earliest known millericrinid genera. For these Middle Triassic millericrinids, the new family Bangtoupocrinidae, comprising the new subfamilies Bangtoupocrininae and Silesiacrininae, is defined. The strongly cirrate genus Qingyanocrinus is assigned to the new family Qingyanocrinidae, whose systematic position is uncertain.In all three species, the morphological features of the columnals characteristically vary in different parts of the stems. The millericrinids were cemented to (secondary) hard substrates by distal encrusting holdfasts. Qingyanocrinus kueichounensis most likely lived on soft substrates and for attachment made use of its rootlike distal stem end and cirri. Stems of Bangtoupocrinus kokeni regenerated after breakage show that these crinoids were able to continue living in spite of the traumatic loss of their basal fixation. Juvenile Encrinus cf. liliiformis Lamarck, 1801, and other invertebrates utilized the crinoids and their skeletal remains as substrates for attachment.