贵州盘县中三叠世混鱼龙类研究进展及“Mixosaurus yangjuanensis Liu and Yin, 2008”的疑问和相关问题  

MIDDLE TRIASSIC MIXOSAURIDS OF PANXIAN,GUIZHOU AND PROBLEMS OF "MIXOSAURUS YANGJUANENSIS LIU AND YIN,2008"

作　　者：江大勇[1] 郝维城[1] Motani R Schmitz L 孙元林[1] 孙作玉[1] 

机构地区：[1]北京大学地质系及地质博物馆,北京100871 [2]Department of Geology,University of California.Davis,CA 95616 8605,U.S.A.

出　　处：《古生物学报》2008年第3期377-384,共8页Acta Palaeontologica Sinica

基　　金：国家自然科学基金(Nos.40672002,40302009);教育部新世纪人才支持计划(NCET-07-0015)联合资助

摘　　要：盘县新民乡羊圈村及其邻区关岭组上段产出两种混鱼龙:Mixosaurus panxianensis Jiang et al.,2006和Phalarodon cf.P.fraasi Merriam,1910,含混鱼龙类化石层时代应为中三叠世安尼期Pelsonian亚期。"Mixosaurus yangjuanensis Liu and Yin,2008"命名所依据的正模标本无关键的头骨特征,选取的头后骨骼做鉴定特征对混鱼龙类种一级分类无意义,鉴定特征所依据的基本骨块存在鉴定错误;"Mixosaurus maotaiensis"的厘定应无效;盘县动物群中无Mixosaurus cornalianus出现。Family Mixosauridae is a monophyletic group strongly supported by the phylogenetic analysis and contains two sister genera, Mixosaurus and Phalarodon. The first mixosaurid record from Asia and Chi na, a single fragmentary specimen from Maotai （north ern Guizhou, southwestern China）, was reported by Young （1960, 1965）, and the name Mixosaurusrnao taiensis Young, 1965 was erected. In subsequent studies, this taxon was rarely considered valid because its holotype is very fragmentary and has no taxonomic value at the species level, and is not diagnostic. Hence, ＂Mixosaurus maotaiensis Young, 1965＂ is a nomen dubium. To preserve this historical species name with the specimens from Panxian of Guizhou may be understandable, but it does not comply with the International Code of Zoological Nomenclature. Abundant and completely articulated skeletons of Middle Triassic marine reptiles, including ichthyosaurs, placodonts, nothosaurs, archoosaur and protorosaur, were recently excavated from the upper Mem ber of Guanling Formation in near Yangjuan Village of Xinmin District in Panxian County （western Guizhou）. The marine reptile fossil horizon can be ascribed to the conodont Nicoraella kockeli Zone, which indicates that the age of the horizon is middle Pelsonian of Middle Anisian in the Middie Triassic. Two mixosaurid taxa from this horizon were reported. One is Mixosaurus panccianensis Jiang et al. , 2006, which is separated from other mixosaur species by both cranial and postcranial characters such as the jugal with a small posteroventral flange. The other is Phalarodon el. P. fraasi Merriam, 1910, which is identified by its characteristic dentition and its narial shelf. Many mixosaurid specimens from Panxian were purchased, not collected scientifically and not prepared in detail by trained technicians. Liu and Yin （2008） erected a name Mizosaurus .yangjuanensis on a small individual in ventral view. The species lacks uniquely derived diagnostic characters, partly because the skull of the only specimen

关 键 词：混鱼龙 关岭组上段 安尼期 中三叠世 盘县 贵州 

分 类 号：Q915[天文地球—古生物学与地层学]