Yang et al.—New paleoscolecid worms from early Cambrian of South China
parts of the intestine are completely flat and preserved in a dark color (Fig. 5.4, 5.5). It leaves little doubt that the sediment was ingested in vivo during normal feeding. Sediment-like pellets in the Kaili material, by contrast, are confined to the black hindgut and retain a slight relief (Fig. 5.6). These gut contents, in our opinion, are not phosphatized alterations of intestine remains as exemplified by García-Bellido et al. (2013), but sediments that support the interpretation of paleoscolecids as deposit-feeders.
Conclusion
The paleoscolecid Shaanxiscolex xixiangensis n. gen. n. sp. is described from the Cambrian Yanwangbian Biota bordering the north margin of the Yangtze Platform near Xixiang County, Shaanxi Province, China, on the basis of fine-scale cuticle organization. S. xixiangensis exhibits a scleritome pattern that is unique among previously reported taxa and reveals a wide- spread geographic distribution of paleoscolecid worms in South China during the early Cambrian period. The paleoecological analysis of paleoscolecids exemplified
by S. xixaingensis and other Cambrian taxa also from South China provides direct evidence for the mode of life and the feeding strategies of this extinct group. It reveals that some paleoscolecids were both deposit feeders and carnivores and may be interpreted as a major subhorizontal and subvertical bioturbators in the substrates of the Cambrian sea, which high- lights the role that paleoscolecid worms may have played in the ‘Cambrian Substrate Revolution.’
Acknowledgments
This work was supported by the Major Basic Research Project of the Ministry of Science and Technology of China under Grant 2013CB835002, the National Natural Science Foundation of China under Grant 41272036, the Scientific Research Founda- tion for Talent Introduced in Guizhou University (Grant No. 2016–83), State Key Laboratory of Palaeobiology and Strati- graphy (Nanjing Institute of Geology and Palaeontology, CAS) (No.173130), and the Research Centre of Palaeontology of Guizhou (Gui, Sci. Z. 2014–4003). We are grateful to W. Liu, Y. Zhang, L. Li, and H. Yun from Northwest University, China, for their kind assistance in fieldwork. The scientific comments of two anonymous reviewers and the linguistic assistance of the journal editor (J. Jin) were greatly beneficial to this paper.
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