Acta Palaeontologica Polonica

A large xenusiid lobopod with complex appendages from the Lower Cambrian Chengjiang Lagerstätte

Jianni Liu, Degan Shu, Jian Han, Zhifei Zhang, and Xingliang Zhang

Acta Palaeontologica Polonica 51 (2), 2006: 215-222

A large lobopod, Jianshanopodia decora gen. et sp. nov., with body length (excluding appendages) about 220 mm from the Lower Cambrian Haikou section, near Kunming, Yunnan, southwest China, shows a mixture of characters, including features of the lobopod Xenusion Pompeckj, 1927, e.g., a large cylindrical body with annulations, stout and strong lobopod appendages each bearing bases of serial tubercles, and of Aysheaia Walcott, 1911, i.e., a pair of large frontal appendages. This suggests that the new genus might be a connecting link between Xenusion and Aysheaia. Besides, Jianshanopodia shares some features with the Early Cambrian stem group arthropod Pambdelurion Budd, 1997, and Kerygmachela Budd, 1993, e.g., the pairs of mid-gut diverticula, the possible presence of tail fan, the mouth cone, the frontal pharyngeal structures and the pharynax are surrounded by the bases of the large frontal appendages. However, compared with a series of segmentally arranged, imbricating, paddle-shaped, movable lateral flaps of both Pambdelurion and Kerygmachela, Jianshanopodia possesses distinct complex appendages with tree-like or lamellate branches. The discovery of this rare transitional form not only throws new light on the early diversification of lobopods, and may also have significance with respect to the origin of arthropods.

Key words: Arthropoda, Lobopodia, Xenusiidae, arthropod origin, Chengjiang Lagerstätte, Cambrian, China.

Jianni Liu [eliljn@nwu.edu.cn], Jian Han [ elihanj@nwu.edu.cn ], Zhifei Zhang [ elizf@nwu.edu.cn ], and Xingliang Zhang [ xlzhang@pub.xaonline.com ], Early Life Institute and Key Laboratory for Continental Dynamics of the Ministry Education, Northwest University, Xi-an, 710069, China;Degan Shu [ elidgshu@nwu.edu.cn ], Early Life Institute and Department of Geology, Northwest University, Xi-an, 710069, China, School of Earth Sciences and Resources, China University of Geosciences (Beijing), 100083, China.