摘要
Lapworthella属原有28种,经过笔者研究,仅有14种可以成立(包括新种)。Lapworthella xinjiangensis sp. nov.产于新疆乌什玉尔吐斯组,它的发现为塔里木地块下寒武统的对比提供了新依据。
Lapworthella xinjiangensis sp. nov. has been found in Wushi, Xinjiang, Northwest China (about 80°E longitude and 41°N latitude) (Text-fig. 2). Geologically, the fossil locality is on the northwestern border of the Tarim Block. The new species occurs in the Yurtus Formation in which some other small shelly fossils were earlier found, such as Cambroclavus (=Sugaites) and bradoriids. The Yurtus Formation is mainly composed of phosphate and argillaceous limestone and dolostone which are conformably overlain by the Xiaorbulak Formation containing the Early Cambrian trilobite Shizhudiscus. Disconformably underlying the Yurtus Formation is the Qigebulak Formation, which is mainly composed of dolostone, with late Precambrian stromatolites and microfossils, indicating that the Yurtus Formation is the Lowest Cambrian strata in the northwestern Tarim Block. The age of the Yurtus Formation was formerly considered as Meishucunian, but the fossils of the Yurtus Formation are different from those of the Meishucunian fauna. The species of Lapworthella are also different in Tarim and in Yangtse. These indicate that the age of the Yurtus Formation may be younger than Meishucunian. This paper gives a review of the genus Lapworthella. Up to the present time, totally 28 species have been named under this genus excluding some undetermined species or new species of Lapworzhella. Some of the species do not belong to Lapworthella at all; some are synonyms because they were named from the sclerite forms. As a result, only 14 of them are considered as valid species of Lapworthella, with their worldwide distribution given in Text-fig. 1. The author proposes that 5 families should be included in the Order Tommotiida, namely, Tommotiidae, Tannuolinidae, Kelanellidae, Lapworthellidae and Sunnaginidae. There is only one genus Lapworthella in Family Lapworthellidae, and the septum-bearing tommotiids should be included in Family Kelanellidae. The fine ornaments on the surface of the sclerites can be used as a criterion to distinguish the differ
出处
《古生物学报》
CAS
CSCD
北大核心
1992年第1期108-116,152,共9页
Acta Palaeontologica Sinica
