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Rapid growth in a large Cambrian apex predator
Yu Wu1,2, Stephen Pates2, Daniel Pauly3
1State Key Laboratory of Continental Dynamics and Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, China.
National Science Review
|February 5, 2024
Summary
Early Cambrian arthropods like Amplectobelua symbrachiata grew rapidly, reaching up to 90 cm. This fast growth strategy was key to the Cambrian explosion's evolutionary arms race.
Area of Science:
- Paleontology
- Evolutionary Biology
- Developmental Biology
Background:
- Ontogenetic data for early euarthropods are scarce, hindering understanding of past life's ecology and evolution.
- Reconstructing life histories of fossil animals presents significant challenges.
Purpose of the Study:
- To investigate the growth trajectory of frontal appendages in the Cambrian apex predator Amplectobelua symbrachiata.
- To understand the life history strategy of this early arthropod and its role in the Cambrian explosion.
Main Methods:
- Analysis of 432 Amplectobelua symbrachiata specimens from the early Cambrian Chengjiang biota.
- Isometric growth analysis of frontal appendages.
- Electronic Length-Frequency Analysis (ELEFAN) to assess growth rates compared to extant arthropods.
Main Results:
- Amplectobelua symbrachiata appendages exhibited isometric growth.
- An estimated maximum body size of approximately 90 cm was determined for the species.
- Individuals demonstrated rapid growth rates when compared to modern arthropods.
Conclusions:
- Amplectobelua symbrachiata was an extremely fast-growing Cambrian arthropod.
- Its unusual life history strategy likely contributed to the evolutionary 'arms race' during the Cambrian explosion.
- This study provides crucial ontogenetic data for early diverging euarthropods.
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