Advent of three-dimensional sediment exploration reveals Ediacaran-Cambrian ecosystem transition

Trace fossils offer critical insights into animal diversification and ecosystem evolution during the Neoproterozoic-Phanerozoic transition. <i>Treptichnus</i> represents the earliest known three-dimensional burrow system, which co-occurred with Ediacara-type fossils in the Shibantan assemblage (~550 to 543 million years ago). Integration with <i>Lamonte</i> and tadpole-like traces reveals important behavioral innovations from simple horizontal locomotion to complex sediment penetration, thereby bridging ecological and behavioral transitions across the Ediacaran-Cambrian boundary. The advent of three-dimensional sediment exploration fundamentally altered benthic ecodynamics and disrupted microbial mat stability. This shift reflects a fundamental restructuring of infaunal habitats, which temporally coincided with the decline of matground-related Ediacaran macro-organisms. These innovations laid the foundation for Phanerozoic animal-sediment interactions, catalyzing a pivotal ecological transition predating yet enabling the Cambrian Explosion.