Rapid growth in a large Cambrian apex predator

Yu Wu; Stephen Pates; Daniel Pauly; Xingliang Zhang; Dongjing Fu

doi:10.1093/nsr/nwad284

Rapid growth in a large Cambrian apex predator

Natl Sci Rev. 2023 Nov 3;11(3):nwad284. doi: 10.1093/nsr/nwad284. eCollection 2024 Mar.

Authors

Yu Wu^{1

2}, Stephen Pates², Daniel Pauly³, Xingliang Zhang^{1

4}, Dongjing Fu¹

Affiliations

¹ State Key Laboratory of Continental Dynamics and Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, China.
² Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
³ Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
⁴ Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.

Abstract

Despite the importance of ontogenetic data on early diverging euarthropods to our understanding of the ecology and evolution of past life, the data are distinctly lacking, as reconstructing life histories of fossil animals is often challenging. Here we report the growth trajectory of frontal appendages of the apex predator Amplectobelua symbrachiata, one of the most common radiodont arthropods from the early Cambrian Chengjiang biota (c. 520 Ma) of China. Analysis of 432 specimens (9.1-137.1 mm length; 1.3-25.6 mm height) reveals that appendages grew isometrically, with an estimated maximum size of the whole animal of c. 90 cm. Individuals grew rapidly compared to extant arthropods, as assessed using the electronic length-frequency analysis (ELEFAN) approach. Therefore, we show that the Cambrian apex predator A. symbrachiata was an extremely fast-growing arthropod, with an unusual life history strategy that formed as part of the escalatory 'arms race' that shaped the Cambrian explosion over 500 Ma.

Keywords: Cambrian Explosion; Radiodonta; growth dynamics; post-embryonic development; stem-group Euarthropoda.