Skip to main content

Research Repository

Advanced Search

No (Cambrian) explosion and no (Ordovician) event: A single long-term radiation in the early Palaeozoic

Servais, Thomas; Cascales-Miñana, Borja; Harper, David A.T.; Lefebvre, Bertrand; Munnecke, Axel; Wang, Wenhui; Zhang, Yuandong

No (Cambrian) explosion and no (Ordovician) event: A single long-term radiation in the early Palaeozoic Thumbnail


Thomas Servais

Borja Cascales-Miñana

Bertrand Lefebvre

Axel Munnecke

Wenhui Wang

Yuandong Zhang


The Cambrian ‘Explosion’, located by many authors between 540 and 520 million years ago (Ma), is considered to be an abrupt appearance in the fossil record of most animal phyla, with a sudden increase of complex morphologies across metazoan groups. In a few recent papers, the Great Ordovician Biodiversification ‘Event’ (GOBE) has similarly been restricted to a single dramatic biodiversification ‘event’ in the Darriwilian Stage of the Middle Ordovician Series, between 470 and 455 Ma, although historically the biodiversification is considered as an aggregation of radiation ‘events’ capturing a large and complex increase of taxonomic diversity of marine invertebrates covering the entire Ordovician. A review of biodiversity curves of marine organisms during the early Palaeozoic, including some based on data in the Paleobiology Database (PBDB) and the Geobiodiversity Database (GBDB), points towards a single, large-scale, long-term early Palaeozoic radiation of life that already started in the late Precambrian. An abrupt ‘explosion’ of diversity in the Cambrian or a significant ‘event’ in the Ordovician are not visible in our biodiversity studies, because they are either regional, or only reflect a single group of organisms. It is evident that the datasets remain incomplete, in particular those for many geographical areas and for several fossil groups, that are not covered by the PBDB and GBDB; also, such areas remain so far poorly or entirely unstudied. Some recently published biodiversity curves have to be considered with care, as the truly global diversity estimates of marine organisms during the early Palaeozoic remain elusive. Here, we argue that published curves of taxonomic richness, which show distinct periods of diversification, cannot sufficiently be disentangled from biases. We therefore question the existence of a distinct Cambrian ‘Explosion’ and global Ordovician ‘Event’ in the global datasets. Both terms, Cambrian ‘Explosion’ and Great Ordovician Biodiversification ‘Event should be used as conceptional terms only. The first represents the appearance of almost all animal phyla during the late Precambrian and early Cambrian, whereas the second term embraces the numerous and complex radiations that occurred during the entire Ordovician.


Servais, T., Cascales-Miñana, B., Harper, D. A., Lefebvre, B., Munnecke, A., Wang, W., & Zhang, Y. (2023). No (Cambrian) explosion and no (Ordovician) event: A single long-term radiation in the early Palaeozoic. Palaeogeography, Palaeoclimatology, Palaeoecology, 623, Article 111592.

Journal Article Type Article
Acceptance Date Apr 22, 2023
Online Publication Date May 10, 2023
Publication Date 2023-08
Deposit Date Oct 30, 2023
Publicly Available Date Oct 30, 2023
Journal Palaeogeography, Palaeoclimatology, Palaeoecology
Print ISSN 0031-0182
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 623
Article Number 111592
Keywords Paleontology; Earth-Surface Processes; Ecology, Evolution, Behavior and Systematics; Oceanography
Public URL


You might also like

Downloadable Citations