The Phylogeny of the Antiarcha (Placodermi, Pisces), with the description of Early Devonian antiarchs from Qujing, Yunnan, China


en Bulletin du Muséum national d'Histoire naturelle, 4ème série – section C – Sciences de la Terre, Paléontologie, Géologie, Minéralogie 18 (2-3) - Pages

Published on 01 August 1996

Five new antiarchs (Yunnanolepis porifera n.sp., Mizia longhuaensis n.gen., n.sp., Phymolepis guoruii n.sp., Chuchinolepis robusta n.sp. and C. sulcata n.sp.) are described on the basis of the new material from the Early Devonian of Qujing, Yunnan Province, south-western China. Y. chii is reexamined to show the Chang's apparatus and lateroventral fossa of the trunk-shield. New material of Qujing comprises also Heteroyunnanolepis qujingensis, Y . sp. from the Xitun Formation, P. cuifengshanensis and Zhanjilepis aspratilis from the Xishancun Formation, C. gracilis and C. qujingensis from the Xishancun and Xitun Formations, and an unnamed antiarch from the Xitun Formation. It is proposed that Procondylolepis, as well as Qujinolepis, is the junior synonym of Chuchinolepis. The pectoral fin articulation of the Chuchinolepididae is argued to have only one dermal joint. It is suggested that the pectoral fin of the Chuchinolepididae is laterally compressed and that the fossa on the parabrachial process is the attachment area for the abductor muscle of the fin. A cladistic analysis of antiarchs is presented. 32 equally parsimonious trees are found, and a strict consensus tree is constructed. The monophyly of the Yunnanolepidoidei is corroborated in the cladogram, with an emended definition of the group. The Chuchinolepididae, Vanchienolepis , and an unnamed antiarch are included in the Yunnanolepidoidei. Minicrania (Zhu & Janvier 1996) is the sister-group of the antiarchs possessing the brachial process and funnel pit. The Bothriolepidoidei, as previously defined, turn out to be a paraphyletic group. The Microbrachiidae are at the base of the Euantiarcha. is assumed to be the nearest sister-group of the Asterolepidoidei, and Hunanolepis is placed at the base of the Asterolepidoidei.
Keywords :
Antiarcha, Early Devonian, Morphology, Phylogeny, China