Some Discussions Of Metazoan Evolution Characteristics Of The Cambrian Explosion

Comparing the age, biotic characters and sedimentary environment of the Burgess Shale-type soft-bodied fossil Biotas and the phosphated Lagerstatte in South China, nine Burgess Shale-type fossil Biotas with exception of Yanjiahe biota and Kuanchuanpu biota are regarded to represent a series of closely related biological communities which lived in muddy sandy substrates and showed gradual transitions in space-time distributions. As a result, the Burgess Shale-type fossil Biotas in South China should have a wider distribution during the Middle-Late Cambrian and the Cambrian faunas should be the subject and the source of Paleozoic metazoan.The author analyzed over ten Burgess Shale-type soft-bodied fossil Biotas in South China and holds that Cambrian explosion is essentially a nearly20-million-year multistage process during which the Neoproterozoic biota in Early Cambrian evolved to various bilateria performing different biomineralization characters and resembling modern marine ecological constructure in Cambrian under the circumstance of global sea-level and oxygen proportion reaching a certain level.The Cambrian explosion does great influence, especially on the evolutionary developmental biology, evolutionary ecology and macroevolution. The reproductive strategy changed greatly with hard substrate, predatory relation and ecological space expansion indicating the gradual foundation of modern marine ecosystem and with predatory relation stimulating coevolution.From of research of reproductive strategy of Cambrian fauna, the author thinks that the Bivalved bradoriid arthropod Kunmingella douvillei (Mansuy,1912) is the most common species in the Lower Cambrian Chengjiang Lagerstatte. Its soft anatomy has been reported based on the well-preserved specimens. However, as with other Cambrian arthropods, their reproductive behavior and reproductive strategy is poorly documented. Rare specimens of Kunmingella douvillei preserved with eggs have been reported. Our new collections confirm that the eggs were directly attached to the last three pairs of biramous appendages and verify the head-trunk boundary suggested by previous work. The brooding behavior of Kunmingella douvillei was most probably related to its small body size, as in living crustaceans. The female Kunmingella douvillei could carry50-80eggs ranging from150-180μm in diameter, possibly indicating a K-reproductive strategy of ecology. Its ontogenetic and reproductive mode may have been an adaptive strategy in response to increasing predatory pressure of the outside environment across the Ediacaran-Cambrian boundary. All of the three main directions of development in the life history of living marine invertebrates namely planktotrophic larvae, lecithotrophic larvae, and brood care most have evolved by the Stage3of the Cambrian.The author has studied coprolites in Cambrian Chengjiang Lagerstatte and Southern Shaanxi. The author has considered animal feeding strategy in Cambrian. The Chengjiang Lagerstatte coprolites mainly have three types:food miniature animal coprolites, food mud animal coprolites, food larger animal coprolites. The shape type of coprolites has concentric coprolites; elongate, ribbon-like coprolites; elliptical coprolites. The coprolites inclusions have trilobites, bradoriids, waptiids, hyolithes and other fragments or debris of animals. It is explained that complicated food chain in the early Cambrian Chengjiang Lagerstatte has been formed. Animals had a certain ability of eating hard diet, namely it is appeared that co-evolution between shell animals and durophagous shell animals.