Fossilized gut of the trilobite Lioparia bassleri and the distribution of exceptional preservation in the Cambrian Stage 4-Drumian Manto Formation of North China

摘要

The preservation of digestive structures of trilobites is not unique but recognition and reporting about these remains are rare. Here we describe a specimen of Lioparia bassleri ResserandEndo, 1937, recently collected from the Weifang Biota in the Manto Formation (Cambrian, Miaolingian, Shandong, North China). This exceptionally preserved specimen displays the remains of the digestive system in the cephalon as well as in thoracic and pygidial parts of the body. The morphology of the remains of soft parts preserved in the specimen agrees with a simple digestive tract which included a simple gut tube in the thorax and pygidium associated with four pairs of cephalic gut diverticulae in the glabella. The morphology of the digestive tract of L. bassleri compares favourably with earlier observations on trilobites that had gut diverticulae. The preservation of the digestive system in the studied trilobite confirms that the depositional environment of the Manto Formation was favourable to soft-tissue preservation. Earlier papers on trilobites with preserved soft parts from China are summarized. Exceptional preservation of sponges, palaeoscolecids, radiodonts, bivalved arthropods, trilobites, and echinoderms in the Manto Formation is briefly discussed.