Unique Cambrian trilobite Eodontopleura: an example of strong convergence in trilobite evolution

Abstract

ABSTRACT The lower Cambrian trilobite Eodontopleura Chien and Lin in Yin and Lee 1978 from South China was once thought to be an ancestor of the post-Cambrian trilobite Odontopleurida due to its unique odontopleurid-like glabella. Here, we revise this genus as an oryctocephalid based on the articulated exoskeletons found recently in the Balang Formation (Cambrian Series 2, Stage 4) of South China. Phylogenetic analysis supports that Eodontopleura represents a typical example of trilobite convergent evolution, suggesting that even the most exclusive features may have been repeated in the evolutionary history of trilobites, which additionally reminds us of the universality of convergence and its possible misleading effect on trilobite taxonomic studies. Moreover, our discovery indicates the remarkable specialisation potential of oryctocephalids, which highlights the evolution of early deep-water trilobites.