A chancelloriid-like metazoan from the early Cambrian Chengjiang Lagerstätte, China

Abstract

Nidelric pugio gen. et sp. nov. from the Cambrian Series 2 Heilinpu Formation, Chengjiang Lagerstätte, Yunnan Province, China, is an ovoid, sac-like metazoan that bears single-element spines on its surface. N. pugio shows no trace of a gut, coelom, anterior differentiation, appendages, or internal organs that would suggest a bilateral body plan. Instead, the sac-like morphology invites comparison with the radially symmetrical chancelloriids. However, the single-element spines of N. pugio are atypical of the complex multi-element spine rosettes borne by most chancelloriids and N. pugio may signal the ancestral chancelloriid state, in which the spines had not yet fused. Alternatively, N. pugio may represent a group of radial metazoans that are discrete from chancelloriids. Whatever its precise phylogenetic position, N. pugio expands the known disparity of Cambrian scleritome-bearing animals, and provides a new model for reconstructing scleritomes from isolated microfossils.

New well-preserved scleritomes of Chancelloriida from early Cambrian Guanshan Biota, eastern Yunnan, China

“…was mentioned by Hu et al (2013) and considered to be a new kind of chancelloriid, but no detailed studies were provided. Hou et al (2014) described a chancelloriid-like metazoan from the Chengjiang Lagerstätte and established the genus Nidelric , which has many similarities to the metazoan described here. Nidelric pugio Hou et al, 2014 is the type and only other known species.…”

“…Hou et al (2014) described a chancelloriid-like metazoan from the Chengjiang Lagerstätte and established the genus Nidelric , which has many similarities to the metazoan described here. Nidelric pugio Hou et al, 2014 is the type and only other known species. The diagnosis of Nidelric is emended from Hou et al (2014), based on the complexity of spines, which is discussed below.…”

“…Nidelric pugio Hou et al, 2014 is the type and only other known species. The diagnosis of Nidelric is emended from Hou et al (2014), based on the complexity of spines, which is discussed below.…”

Naked chancelloriids from the lower Cambrian of China show evidence for sponge-type growth

“…We interpret the ring-shaped 'doughnut' structures to be the sites of former sclerite attachment, based on their size and distribution (matching in their density the densest non-apical sclerite arrays). Comparable structures were found to be associated with the sclerite bases in Nidelric pugio [18], and partly three-dimensionally preserved chancelloriids occur in which sclerites are mounted 3) in the specimen with the largest preserved body width (70 mm; YKLP 13506) predicts a body length of more than 30 cm. Applying the same calculation to the largest incomplete fragment (minimum width 115 mm, YKLP 13507) predicts a body length of around 50 cm.…”

“…The Chengjiang biota of Yunnan Province, South China [14], has yielded exceptionally preserved, fully articulated chancelloriid specimens, some currently assigned to Allonnia phrixothrix [15], of which A. junyuani [16] is a junior synonym [4], and Allonnia erjiensis [17]. In addition, the Chengjiang species Nidelric pugio [18] is based on a single specimen of a chancelloriid-like animal with unique, single-rayed sclerites. Specimens have also been reported which are characterized by a low density of proportionally small sclerites [15,16,19].…”