Oldest Phosphatic Stromatoporoid Sponge Discovered in South China: A Groundbreaking Fossil Find
A team of international scientists has made a remarkable discovery in South China—the oldest known phosphatic stromatoporoid sponge, dating back approximately 480 million years to the Early Ordovician period. This finding provides critical insights into early reef-building ecosystems and the evolution of biomineralization in ancient marine life.
Revolutionizing Our Understanding of Ancient Reefs
Stromatoporoid sponges played a pivotal role in reef construction during the Paleozoic era, much like modern corals do today. They became dominant reef builders during the middle Paleozoic, particularly from the late Middle Ordovician to the Devonian period, marking a major transition from microbial-dominated reefs to skeletal-dominated reef ecosystems.
Previously, scientists believed that stromatoporoid reefs emerged abruptly during the late Darriwilian period (approximately 460 million years ago). However, this latest discovery challenges that notion, pushing back their origins by nearly 20 million years and shedding light on their early evolutionary history.
Discovery of Lophiostroma leizunia
An international research team led by experts from the Nanjing Institute of Geology and Paleontology at the Chinese Academy of Sciences unearthed an exceptionally well-preserved phosphatic stromatoporoid sponge in Yuan’an, Yichang, South China. The newly identified species, Lophiostroma leizunia, is a game-changer in the field of paleontology.
This ancient sponge not only extends the fossil record of stromatoporoids but also provides crucial evidence regarding the early biomineralization strategies of prehistoric marine animals.
South China: A Fossil Treasure Trove
South China is renowned for its exceptional fossil preservation and its rich Early Paleozoic marine ecosystems. Scientists have extensively studied the Ordovician strata in this region, particularly in relation to the Great Ordovician Biodiversification Event (GOBE)—a significant period of marine biodiversity expansion. The discovery of Lophiostroma leizunia adds to this region’s reputation as a key site for understanding early marine evolution.
A Unique Biomineralization Strategy
What makes Lophiostroma leizunia particularly fascinating is its skeletal composition. Unlike any previously known sponge, it constructed its skeleton using fluorapatite, a phosphate mineral. This discovery establishes the phylum Porifera (sponges) as the first known animal group to utilize all three primary biominerals: silica, calcium carbonate, and calcium phosphate.
This unique adaptation suggests that early sponges had the genetic flexibility to employ diverse biomineralization strategies, a critical evolutionary advantage that may have influenced the development of modern marine organisms.
Ancient Reef Ecosystems and Their Complexity
Fossil evidence indicates that Lophiostroma leizunia played a vital role in reef construction, binding together various reef components such as calcimicrobes, lithistid sponges, Calathium, and echinoderms. These reefs exhibited a level of ecological complexity comparable to much later reef systems, providing a window into the dynamic interactions of early marine life.
Implications for Evolutionary and Environmental Studies
This groundbreaking discovery enhances our understanding of early reef ecosystems and the evolution of biomineralization in the animal kingdom. It also highlights the impact of environmental factors on biological evolution during one of Earth’s most transformative periods.
The research findings have been published in the prestigious journal Proceedings of the National Academy of Sciences.
Reference:
Zhang, Yuan-Dong et al. Phosphatic stromatoporoid sponges formed reefs ~480 Mya, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2426105122.
This discovery represents a significant step forward in paleontology, providing new perspectives on ancient marine life and the intricate evolutionary pathways that shaped modern reef ecosystems.