A Parvancorina-like arthropod from the Cambrian of South China

• Published in: Historical biology 2006-03, Vol.18 (1), p.33-45
• Main Authors: Lin, Jih-Pai, Gon, Samuel M., Gehling, James G., Babcock, Loren E., Zhao, Yuan-Long, Zhang, Xing-Liang, Hu, Shi-Xue, Yuan, Jin-Liang, Yu, Mei-Yi, Peng, Jin
• Format: Article
• Language: English
• Subjects: Arachnomorpha; Burgess Shale-type deposits; Ediacaran; Kaili Formation; Parvancorinomorpha; Primicaris; Skania; Vendobionts
• ISSN: 0891-2963; 1029-2381
• DOI: 10.1080/08912960500508689

Constraining the origin of animal groups is allowed, to some extent, by discoveries of Cambrian Lagerstätten that preserve both mineralizing and nonmineralizing organisms. A new species is reported here of the Cambrian arthropod Skania, which bears an exoskeleton that shares homologies with the Neoproterozoic (Ediacaran) organism Parvancorina and firmly establishes a Precambrian root for arthropods. A new monophyletic group, Parvancorinomorpha, is proposed as the first clade within the arthropod crown group demonstrably ranging across the Neoproterozoic-Paleozoic transition. The Parvancorinomorpha is interpreted to be the sister group of the Arachnomorpha. Incipient cephalization in Skania and related genera represents a step in the progression toward division of a cephalon from a large posterior trunk as shown in Cambrian arachnomorphs such as naraoiids and the addition of a pygidium and thoracic tergites as shown in the arachnomorph clade basal to trilobites. This evidence can serve as a new calibration point for estimating the divergence time for the last common ancestor of arthropods and priapulids based on molecular clock methods.