Ecology and phylogenetic affinity of the early Cambrian tubular microfossil Megathrix longus

59 1 January 13 28 10.1111/pala.12201

SHANG, X., LIU, P., YANG, B., CHEN, S., WANG, C. 2016. Ecology and phylogenetic affinity of the early Cambrian tubular microfossil Megathrix longus. Palaeontology, 59, 1, 13-28.

Xiaodong Shang, Pengju Liu, Ben Yang, Shouming Chen and Chuchu Wang
  • Xiaodong Shang - Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China (email: shangxdong@sina.com)
  • Pengju Liu - Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China (email: pengju@cags.ac.cn)
  • Ben Yang - Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China (email: yangben8@gmail.com)
  • Shouming Chen - Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China (email: ming1003@163.com)
  • Chuchu Wang - Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China (email: wangcugb@foxmail.com)
  • Chuchu Wang - School of Earth Sciences and Resources, China University of Geosciences, Beijing, China
  • Issue published online: 18 DEC 2015
  • Article first published online: 13 OCT 2015
  • Manuscript Accepted: 17 AUG 2015
  • Manuscript Received: 29 MAY 2015
National Natural Science Foundation of China. Grant Number: 41172035 MLR Public Benefit Research Foundation. Grant Number: 201411044 China Geological Survey. Grant Number: 12120114077901

Abundant, exquisitely preserved specimens of the enigmatic tubular microfossil Megathrix longus are reported from the early Cambrian Yanjiahe Formation in the Yangtze Gorges area. Studies of their morphology and taphonomy reveal that the inner cross-wall of Megathrix longus is topographically flat, the trichome terminus is blunt and closed, and incomplete cross-walls are regularly intercalated between complete ones. The deformation of trichomes, as well as the corrugation of their cross-walls, are postmortem features caused by compaction, rather than biological features as previously interpreted. Statistical analysis indicates that chamber division is accomplished by the closure of incomplete cross-walls. This process, which contributed to trichome growth, is extremely similar to that of modern Oscillatoriaceae. Trichome fragmentation was also observed in a series of specimens, which closely resembles that of cyanobacteria, particularly the Oscillatoriaceae. The termini of Megathrix longus suggest that it was planktonic. In general, Megathrix longus bears a close affinity to the extant Oscillatoriaceae (Cyanophyta).

Data for this study are available in the Dryad Digital Repository http://dx.doi.org/10.5061/dryad.gc1jf Wiley Online Library