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How are trace fossils used to study changes in animal behavior near the beginning of the Cambrian?
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Cambrian Period
Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Cambrian Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.
Trace fossils are essential for studying animal behavior near the beginning of the Cambrian because they provide independent evidence of accelerated diversification and increased complexity in animal behaviour that body fossils alone may not fully capture.1
Researchers use these fossils to track several key behavioral shifts:
- Increased Bioturbation: Trace fossils document a marked increase in bioturbationāthe churning and stirring of seafloor sediment by animals. While late Precambrian (Ediacaran) traces were primarily simple surface trails, Lower Cambrian rocks show a significant rise in the intensity and depth of sediment burrowing.1
- Locomotion and Foraging: Early Cambrian traces reveal more complex and diverse patterns of movement and feeding. These include improvements in locomotion, such as the development of legs in arthropods, and new foraging strategies.2
- Sediment Penetration: Unlike earlier forms that largely lived on the seafloor surface, Cambrian animals demonstrated a greater ability to penetrate and inhabit the sediment, reflecting a shift toward more active, bottom-dwelling (benthic) lifestyles.324
- Branching Patterns: Specific traces, such as T. pedum, which marks the base of the Cambrian, demonstrate the first regularly branching burrow patterns, signaling a transition toward more sophisticated behavioral repertoires.3