The earliest known 3D bro systems were exposed in Hubei’s Shibenton Biota

A research team from the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences (NIGPAS) has made breakthroughs in the study of the Shibantan biota in Yicheng, Hubei Province, uncovering the oldest complex three-dimensional systems to date. Preserved in an approximately 550-million-year-old strata, these trace fossils show that complex animal behaviors were modifying seafloor environments about 10 to 10 million years earlier than previously thought.

Appears at work Science advances.

The Ediacaran-Cambrian transition, about 53,539 million years ago, marks the most significant ecosystem revolution in Earth’s history. A key driver of this environmental shift was the transition of metazoan behavior from simple two-dimensional surface activities to deep three-dimensional exploration in sediments.

This “substrate revolution” transformed the seafloor from a homogeneous, mat-ground-dominated system into a heterogeneous, bioturbated modern-style seafloor, permanently altering the trajectory of Earth’s ecological and biological evolution.

The researchers systematically studied trace fossils from the Shibantan biota (about 550–543 million years old). They identified several ichnospecies within the genus Triptychnus and established a new ichnospecies, Triptychnus streptosus. By linking these findings to biota such as previously discovered three-dimensional trace fossils such as Lamonte and tadpole-sized traces, the study provides an in-depth analysis of the evolutionary and ecological significance of the emergence of vertical exploration behavior in animals.

These findings suggest that complex animal behavior emerged during the Cambrian explosion.

Triptychs is an important landmark fossil, representing the first 3D exploration of sediment by animals, and is important in evolutionary biology, animal behavior and ecology.

The first appearance of a member of this genus, T. pedum, formally defines the Ediacaran-Cambrian boundary. A new discovery from the Shibantan biota predicts this revolutionary behavior. In addition to reporting the new species T. streptosis, this study identified other ichnospecies, including TCF. biforex, T. itacarisalis, and T. pollardii show that animal bursting behavior had already achieved considerable diversity by this time.

Additionally, the Shibanton biota preserves other three-dimensional bills, such as lamonte and tadpole-shaped markings. The concentrated occurrence of these vertical exploration behaviors reflects early sediment environmental stability and complex foraging strategies, indicating a progressively improved ability of trace-forming organisms to engineer substrates.

This study found that Lamonte caused extreme bioturbation within the shebanton biota. This not only disrupted the microbial mats on the surface of the sediments, but also destroyed the ecological environment for the Ediacara-type organisms that depended on these mats. This suggests that biobridging may have been a contributing factor in the first extinction event of the Ediacaran biota around 550 million years ago.

The emergence of these complex processes and their overall environmental impact increased toward the end of the Ediacaran period. This resulted in a gradual decline in microbial mats, creating new ecological opportunities for the diversification of other metazoans, steadily eroding the ecological base of Ediacaran-type organisms. Driven by the synergy of various biotic and abiotic factors, this process eventually contributed to profound ecosystem change during the Ediacaran-Cambrian transition.

This study further confirms that the rich and diverse assemblage of fossils and body fossils preserved in the Shibantan biota provides a window into the study of significant ecosystem changes during the transition between the Precambrian and Phanerozoic epochs.