United States
£ GBP
Arthropods from the Lower Cambrian Chengjiang fauna, Yunnan, southwest China, are described and compared with other arthropods, particularly with those of the Middle Cambrian Burgess Shale fauna. Where a direct comparison of taxa can be made, the new interpretations and reconstructions often differ from those based on the less well-preserved Burgess Shale fossils. Primitive arthropod features are represented in many species by, among other things, marked serial similarity in segments and podomeres, a large number of short podomeres in the endopod, a very small head, and stages of head accretion. The most primitive exopod appears to be a simple rounded flap. A slender exopod fringed with setae appears to be a key innovation shared by crustacean-like and trilobite-like arthropods. In the latter, the setae are large and flattened, and their setal character is clearly revealed by the basal articulations. The idea that the 'trilobite appendage' is restricted to trilobites is thus falsified. Within the dorsoventrally flattened trilobite-like arthropods, herein called lamellipedians, compound eyes tended to become dorsal and to become included in the head shield, and the appendages became laterally deflected.
New taxa are as follows. Superclasses: Proschizoramia, Lamellipedia; classes and subclasses: Yunnanata, Paracrustacea, Megacheira, Artiopoda, Nectopleura, Conciliterga, and Petalopleura; orders and families: Fuxianhuiidae and Chengjiangocarididae, Fortiforcipida with Fortiforcipidae, Acanthomeridiida with Acanthomeridiidae, Retifaciida with Retifaciidae, Skioldiidae and Saperiidae, Sinoburiida with Sinoburiidae, and Strabopiida; genera and species: Fortiforceps foliosa n.gen. et sp., Squamacula clypeata n.gen. et sp., Kuamaia muricata n.sp., Skioldia aldna n.gen. et sp., and Almenia spinosa n.gen. et sp.
