Reflections on the Phylogenetic Position of the Cephalocarida
1992; Wiley; Volume: 73; Issue: 5 Linguagem: Inglês
10.1111/j.1463-6395.1992.tb01098.x
ISSN0001-7272
Autores Tópico(s)Geological formations and processes
ResumoAbstract This essay re‐evaluates the phylogenetic position of the Cephalocarida in the light of the recently discovered Orsten (Upper Cambrian) crustaceans, the living Remipedia, and new interpretation of the Paleozoic ‘trilobitomorphs’. The Orsten crustaceans reinforce the belief that cephalocarid external morphology is primitive, except to show that the early crustacean trunk limb was almost surely biramous. The epipod appears to be a synapomorphy of the Cephalocarida, Branchiopoda and Malacostraca, thus justifying the existence of the Thoracopoda, which is coequal to the Maxillopoda and Remipedia. External morphology of the Remipedia is too specialized to support the hypothesis that it approximates that of the urcrustacean. Crustaceans and chelicerates are still best regarded as subgroups of the Schizoramia.
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