Brachiopods From The Cambrian Stage 3 Xiashiba Lagerstatte

The brachiopods are one of the most successful invertebrate phyla which are worldwide distributed in the oceans,displying a high diversity in taxonomy or habitats.Because of their mineralized dorsal and ventral shells,brachiopods have left abundant fossils in the sediments throughout the whole Phanerozoic Era.They appeared first in the earliest Cambrian,then they were survived even after a series of extinctions during the following geological times,and still flourishing in the modern seas.In a recent phylogenetic analysis,the highly diversified phylum Brachiopoda has been subdivided into several subphyla,of which the Xiaoshiba brachiopods dealt with here belong to the Rhynchonelliformea.The Xiaoshiba fossil Lagerst(?)tte is found from the Cambrian(Series 2,Stage 3)Hongjingshao Formation in Kunming,southern China,where the fossil brachiopods are abundant and exquisitely-preserved.Some of them display exceptionally survived soft parts,like pedicle and visceral region.All of these brachiopods coexisting with many other animals,such as worms,bivalved arthropods,stem group euarthropod fuxianhuiids and sabellidae,forming a bioclastic layer in the exposed sequence.Based on sedimentary and taphonomic evidence,the Xiaoshiba brachiopods are epibenthic,adapting a sessile life in the Cambrian sea.The major contributions in the thesis are as follows:1.The morphology of Kutorgina chengjiangensis Zhang et al.,2007 has been described in detail,especially the intact preservation of deltidium plates and chilidium,which gives additional information and new perspectives for a better understanding of the kutorginate brachiopods.2.Two new brachiopod taxa collected from the Xiaoshiba section have been well described and illustrated:Kuangshanotreta sp.,Taruriglossa cf.Taruriglossa platyfaba.Their occurrence infers the high biodiversification of the Xiaoshiba Lagerst(?)tte in Kunming,southern China,and provides fresh data for current studies on Cambrian brachiopods.3.In general,the xiaoshiba fossil assemblage was buried in situ,or just being transported through short distance.As co-occurring with benthic algae in the same mudstone layer,all of the sessile brachiopods are supposed to have lived in a shallow water habitat.Like other Cambrian Burgess Shale Lagesttaten,the Xiaoshiba brachiopods reveal some basic features that were ignored to some extent or absolutely unknown among their ancestral representatives.Accordingly this study provides the primary approach to investigation on the Xiaoshiba brachiopods,and documents substantial material for subsequent studies.