170 Precambrian Geology

Tuesday, 18 October 2005
1:30 PM - 5:30 PM

RESTUDY OF EARLY NEOPROTEROZOIC CARBONACEOUS COMPRESSIONS PARARENICOLA AND PROTOARENICOLA

Paper number: 170-4
Program: Technical Sessions
Time: 2:15 PM – 2:30 PM

Authors

  • Lin Dong Presenting Author
    Virginia Poltechnic Institute and State Univ, Blacksburg, VA
  • Shuhai Xiao
    Virginia Polytechnic Institute and State Univ, Blacksburg, VA
  • Bing Shen
    Virginia Polytechnic Institute and State Univ, Blacksburg, VA
  • Xunlai Yuan
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing
  • Yongbo Peng
    Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing, N/A
  • Xianqin Yan
    Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing, N/A

Abstract

Pararenicola and Protoarenicola are annulated, ribbon-shaped carbonaceous compressions in pre-Cryogenian successions in North China and possibly Russia. They have been interpreted and widely cited as the oldest known metazoans (Sun et al., 1986). This interpretation is supported by a terminal proboscis-like structure that occurs in some specimens. We sampled and examined a large number of Pararenicola and Protoarenicola specimens from the Liulaobei and Jiuliqiao formations (between 850 and 750 Ma) in northern Jiangsu and Anhui provinces of North China. Our study shows that the “large, long, irregular, proboscis-like” structure diagnostic of Pararenicola and the ovate bulbous proboscis-like structure diagnostic of Protoarenicola may be taphonomic variants of holdfast-like structures, with the former being preservational artifact due to physical tearing. Better preserved specimens appear to have discoidal to bulbous holdfast-like structures. Thin section study verifies that both Pararenicola and Protoarenicola consist of an annulated, cylindrical tube attached to a discoidal or bulbous structure that is interpreted as a possible holdfast. Thus, Pararenicola and Protoarenicola are similar to Tawuia -like fossils from the Suket Shale in Vindhyan Supergroup of central India, which bear a smooth cylindrical tube attached to a discoidal holdfast and are interpreted as benthic algae (Kumar, 2001). Our data indicate that Protoarenicola and Pararenicola are probably synonyms and weaken the proboscis and animal interpretation for both genera.

Kumar, S., 2001, Mesoproterozoic megafossil Chuaria–Tawuia association may represent parts of a multicellular plant, Vindhyan Supergroup, Central India: Precambrian Research, v. 106, p. 187-211.

Sun, W., Wang, G., and Zhou, B., 1986, Macroscopic worm-like body fossils from the Upper Precambrian (900-700Ma), Huainan district, Anhui, China and their stratigraphic and evolutionary significance: Precambrian Research, v. 31, p. 377-403.