Morphology and trunk development of the trilobite Arthricocephalus chauveaui from the Cambrian series 2 of Guizhou, South China

Absolute axial growth and trunk segmentation in the early Cambrian trilobite Oryctocarella duyunensis

“…Initial work in this area focused on a ∼429-Myr-old Ma aulacopleurid trilobite, Aulacopleura koninckii, from one locality in the Czech Republic (Fusco et al 2004(Fusco et al , 2014(Fusco et al , 2016. Recently, similar studies have been conducted on other species and at other sites, including some of Cambrian age (e.g., Du et al 2019Du et al , 2020Holmes et al 2020;. Although all such cases have limitations, including the rather specific set of paleoenvironments represented, these studies do offer important insight into how ancient developmental processes were regulated in this early euarthropod clade.…”

Development of the early Cambrian oryctocephalid trilobiteOryctocarella duyunensisfrom western Hunan, China

“…This combination of putative monophyly, long stratigraphic range, and good ontogenetic representation justifies a series of detailed case studies of the development of individual corynexochid species because of the clade's potential for insights into how trilobite life cycles evolved at a relatively fine taxonomic scale. In particular, the abundance of articulated ontogenies for a number of early Cambrian corynexochids from South China permits exploration of how developmental schedules varied among contemporary and rather closely related species (e.g., McNamara et al, 2003, 2006; Dai et al, 2014, 2017; Hou et al, 2015; Lei, 2016; Du et al, 2020), and perhaps, as we suggest below, even within individual species. As opposed to the more traditional, typological approach necessitated where examples are few, these animals offer glimpses into the natural variability of development.…”

Articulated trilobite ontogeny: suggestions for a methodological standard

“…For instance, in arthropods the term “segmentation” is used to describe both a morphological feature (translational body symmetry) and the developmental process that generates it (Fusco and Minelli, 2013; Dai et al, 2017; Du et al, 2020). The term “somitogenesis,” which is sometimes used in trilobite literature to indicate the appearance of new segments in the trunk prior to the onset of maturity (McNamara et al, 2006; Lei, 2016), is not normally used for the segmentation process in extant arthropods, especially in the case of post-embryonic segmentation (anamorphic development).…”