Paleontologists have studied the body shapes of Ediacaran Cambrian organisms by utilizing trace fossils as a stand-in for body fossils.
Reconstruction of early Cambrian marine life in southern China. Image credit: Dongjing Fu.
The Cambrian explosion is often referred to as a pivotal period in Earth’s history when distinct animal body plans emerged.
Most researchers indicate that this event took place between 541 and 530 million years ago, marking the onset of the Cambrian period.
“The Cambrian explosion represents a significant era in the history of life that poses numerous unresolved questions,” stated Dr. Olmo Miguez Saras from the University of Barcelona at the Museum of Natural History in London, alongside Dr. Zekun Wang.
“In investigating biodiversity during this period, paleontological studies primarily concentrate on organisms with hard structures.”
“Nevertheless, microfossil investigations open avenues for understanding the activities of hard, soft-bodied, or skeletal-deficient organisms preserved in stratigraphic records.”
“The microfossil evidence is essential for shedding light on the evolutionary phases dominated by soft-bodied faunas.”
“Fossil traces mirror the behaviors of habitat-forming organisms, determined by their environment and reactions to ecological factors.”
“Consequently, these traces act as indicators of the paleoecological conditions experienced by the organisms that produced them.”
In their research, the authors concentrated on trace fossils from the Ediacaran-Cambrian transition, a period of great paleobiological interest that represents a pivotal moment in the evolution of complex life on Earth.
This transition experienced substantial shifts in biodiversity as well as the structure of organisms and ecosystems.
“The Ediacaran fauna consisted mainly of complex, multicellular, flexible organisms,” noted Dr. Miguez Saras.
“The shift to the Cambrian era involved numerous extinctions within the Ediacaran fauna, accompanied by a rapid diversification of complex multicellular organisms possessing hard structures (e.g., exoskeletons).”
“This encapsulates the core of evolutionary development that led to the emergence of the most modern animal phyla, commonly referred to as the Cambrian Explosion.”
The research indicates that slender-bodied organisms thrived around 545 million years ago during the Ediacaran period.
“These organisms likely possessed a coelomic hydrostatic body with an anteroposterior axis, muscles, and perhaps segmented structures,” Dr. Miguez Saras explained.
“Additionally, these organisms may have exhibited directional movement and possessed sensory capabilities to navigate and feed on diverse substrates in environments dominated by microbial mats.”
“Thus, the so-called Cambrian explosion and its evolutionary significance could have arisen significantly earlier than previously thought.”
“These adaptations in body shape and mobility facilitated early animals in thriving within increasingly dynamic and complex environments, an ecological engineering process that could spur evolutionary innovation.”
The team’s study is slated for publication in the journal Geological.
____
Zekun Wang & Olmo Miguez-Salas. Quantitative decoding of Ediacaran Motion Microfossil Morphology: Evidence for the appearance of elongated anteroposterior body profiles. Geological Published online on June 9th, 2025. doi: 10.1130/g53332.1
Source: www.sci.news
