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Reassessment of the mode of life of Pagetia Walcott, 1916 (Trilobita: Eodiscidae) based on a cluster of intact exuviae from the Kaili Formation (Cambrian) of Guizhou, China




Jih-Pai Lin [], School of Earth Sciences, Ohio State University, Columbus, Ohio 43210, USA; Jin-Liang Yuan [], Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China, 210008; manuscript received 31/08/07; and manuscript accepted on 28/01/08.


Pagetia is the most abundant trilobite in the Kaili Formation (lower to middle Cambrian). During the course of studying the museum collections of Kaili trilobites (n > 1000), a cluster containing 22 pagetiid individuals at various growth stages is noted. Specimens record the growth range from the degree 0 meraspid to late holaspid phases. Based on the relative completeness of the moults except for missing free cheeks, these specimens are interpreted as intact exuviae that had undergone minimal transport prior to burial. If Kaili pagetiids had pelagic or planktonic living habits as previously suggested, it would be difficult to explain the presence of intact exuviae in clusters. Therefore, Kaili pagetiids are interpreted here as having a benthic mode of life after the onset of the meraspid phase.