Phosphatocopida的分支系统分析

he investigation into Orsten-type Phosphatocopida has been as long as 30 years. Phosphatocopida is resolved as the sister-group of Eucrustacea based on the symapomorphies shared by them. Concerning the inner relationships within Phosphatocopida, various schemes have been proposed. However, it was not until 2003 that the computer-based cladistic analysis of Phosphatocopida was made by Maas et al.. Although detailed, the result given by Maas et al. was untenable because they did not notice that species with the same hinge structures should have closer relationships morphologically and also because there are as many as 22 false codings in their data matrix, which did not accord with the description. Moreover, their result is unrepeatable though the same data matrix was adopted. And since 2002, many Orsten-type phosphatocopids were recovered from the Upper Cambrian in South China by Dong et al.. These well-preserved fossils brought us new important information about the morphology and phylogeny of this taxon. So, it is imperative to revise the characters and data matrix and to re-establish the phylogeny of Phosphatocopida. Consequently, we revised and augmented the characters given by Maas et al., made another cladistic analysis of Phosphatocopida based on previous studies and the material from South China, re-established the phylogeny of Phosphatocopida, and discussed the inner relationships within Phosphatocopida. Different from the result given by Maas et al., out analysis supports the taxonomic scheme proposed by Müller in 1982. Accordingly, we discussed the ground pattern character sets of the main monophyletic groups within Labrophora especially within Phosphatocopida, and also the evolutionary trend of some important characters.