PRESERVATIONAL FOLDS SIMULATING TERGITE JUNCTIONS IN TEGOPELTID AND NARAOIID ARTHROPODS

The exoskeleton in the Middle Cambrian Burgess Shale arthropod Tegopel te has previously been described as divided into tergites. Evidence fr om its sister taxon Saperion and from a Naraoia specimen from the Lowe r Cambrian Chengjiang fauna enables a reinterpretation of the suggeste d tergite boundaries in Tegopelte as preservational artefacts. They ar e considered here as folds that were formed during flattening of the u ndivided dorsal shield. As in the Naraoia specimen, the folds were ini tiated in the axial region between appendage pairs and then continue l aterally. In Tegopelte and Saperion, segmentally arranged furrows in t he axial region facilitated fold formation. Characters other than pres ence of thoracic tergites and pygidium must be used to assess the affi nities of Tegopelte.