The second one,represented by the Chengjiang fauna,saw the emergence of the whole lineage of deuterostomes,which includes both the oldest representatives of all the five major living groups in deuterostomes(echinoderms,hemichordates,urochordates,cephalochordates,and the vertebrates) and an extinct Phylum Vetulicolia.

Mitochondrial Genomic Characters of Malacostracans and Sipunculans and the Molecular Evolutionary Research Based on Mitochondrial Genomes;