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1 April 2007 New observations on the palaeoscolecid worm Tylotites petiolaris from the Cambrian Chengjiang Lagerstätte, south China
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Abstract

The Lower Cambrian Chengjiang Lagerstätte provides a remarkable window to enable investigation of the early diversification of introvert worms. Tylotites petiolaris Luo and Hu, 1999 is a very rare animal of the fauna originally regarded as a kind of lobopodian based on an incomplete specimen, but its affinities to recent phyla are still controversial. New materials of the taxon collected in recent years confirm that it is most closely related to the palaeoscolecidians with which it shares features such as a proboscis consisting of a slightly swollen introvert bearing many scalids, a collar (buccal cone) and a spinose pharynx. Both possess a smooth neck as a median zone between the introvert and the trunk, a pair of terminal hooks and a trunk bearing transverse ridges intercalated with furrows. Therefore, a new order Cricocosmida of the class Palaeoscolecida is erected herein based on these shared characters. The trunk spines of T. petiolaris are somewhat dorsoventrally differentiated indicating an epifaunal life on the sea floor. Numerous fine transverse wrinkles possibly beneath the uppermost cuticle of the ventral trunk of the animal are tentatively interpreted as the circular muscles, a feature crucial to understanding the problematic systematic position of the palaeoscolecidians.

HAN JIAN, YAO YANG, ZHANG ZHIFEI, LIU JIANNI, and SHU DEGAN "New observations on the palaeoscolecid worm Tylotites petiolaris from the Cambrian Chengjiang Lagerstätte, south China," Paleontological Research 11(1), 59-69, (1 April 2007). https://doi.org/10.2517/1342-8144(2007)11[59:NOOTPW]2.0.CO;2
Received: 20 November 2005; Accepted: 1 September 2006; Published: 1 April 2007
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