A new Cambrian frondose organism: ‘Ediacaran survivor’ or convergent evolution?

Abstract

Guangweia cheni gen. et sp. nov. is an exceptionally preserved frond-like fossil from the early Cambrian Guanshan biota of SW China, which shares morphological similarities with some characteristic late Ediacaran frondose organisms in comprising a leaf-like frond attached via a stem to a discoidal structure resembling a holdfast. Plausible evidence for tissue differentiation and bilateral symmetry in G. cheni implies a eumetazoan affinity. However, G. cheni profoundly differs from Ediacaran frondose taxa in several morphological characters, including its possession of an unusual wedge-shaped apical structure. These observations preclude direct phylogenetic relationships with known Ediacaran forms. Instead, G. cheni may record convergent evolution of a frondose bodyplan: a possibility that should be entertained for other purported Cambrian frondose taxa. Supplementary material: A supplementary figure and sketch, scanning electron microscope–energy dispersive X-ray (SEM-EDX) elemental maps and spectra, and detailed images, interpretative drawings and measurements are available at https://doi.org/10.6084/m9.figshare.c.6294893 Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/topic/collections/advances-in-the-cambrian-explosion