2005 Salt Lake City Annual Meeting (October 16–19, 2005)

Paper No. 4
Presentation Time: 2:15 PM


DONG, Lin1, XIAO, Shuhai2, SHEN, Bing2, YUAN, Xunlai3, PENG, Yongbo3 and YAN, Xianqin4, (1)Department of Geoological Sciences, Virginia Poltechnic Institute and State Univ, Blacksburg, VA 24061, (2)Department of Geosciences, Virginia Polytechnic Institute and State Univ, Blacksburg, VA 24061, (3)Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing, 210008, China, (4)Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing, China, lindong@vt.edu

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.