New ontogenetic information on Duyunaspis duyunensis Zhang & Qian in Zhou et al., 1977 (Trilobita, Corynexochida) from the Cambrian and its possible sexual dimorphism

Abstract

Lei, Q.P., September .2015. New ontogenetic information on Duyunaspis duyunensis Zhang & Qian in Zhou et al., 1977 (Trilobita, Corynexochida) from the Cambrian and its possible sexual dimorphism. Alcheringa 40, XXX–XXX. ISSN 0311-5518.The hypostomal condition and the complete ontogenetic development of Duyunaspis duyunensis Zhang & Qian in Zhou et al., 1977 are restudied on the basis of abundant specimens from the Balang Formation (Cambrian, Qiandongian) in Zila Village, Paiwu Township, Huayuan County, Hunan Province. The relatively complete ontogenetic series (degree 0 to 9) provides new evidence that the holaspis of this species has nine rather than seven thoracic segments as proposed by McNamara et al. (2006). Comparisons between Duyunaspis duyunensis and two associated species, Arthricocephalus chauveaui and Changaspis elongata, support its placement in the Subfamily Oryctocarinae. Moreover, based on observations of a large number of specimens, the presence of an anterior indentation on the pygidial end is possibly representative of sexual dimorphism.Qianping Lei [cicelyapple@126.com], Natural Department, Changzhou Museum, Changzhou, Jiangsu Province, 213022, PR China; State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, PR China.