480-million-year-old sponge discovered in China built Earth's first skeletal reef

Yahoo

04-04-2025

The discovery of a 480-million-year-old sponge in China has revolutionized scientists' understanding of early reef ecosystems and biomineralization.
As published in the journal PNAS, Chinese scientists made a breakthrough when identifying a Lophiostroma leizunia, an exceptionally preserved ancient sponge crucial in building reefs during a transitory phase in the planet's evolution.
Dating back 480 million years, the specimen from Yuan'an, Tichang, South China is the oldest Stromatoporoid sponge ever found. It represents a major transition from a microbial-dominated to a skeletal-dominated reef ecosystem, as the sponge built these early reefs with unique characteristics to its class.
Stromatoporoids provided the structure for the first skeletal reefs, but sooner than scientists thought, they effectively changed history books. Up until this astonishing find, they believed that stromatoporoid reefs had developed around 460 million years ago. Now, scientists can gain new insights into the early biomineralization of ancient animals.
A team of international scientists from the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences found the oldest phosphatic stromatoporoid sponge on record in South China.
The Lophiostroma leizunia has pushed back the fossil record of this group of sponges and the reefs they produced 20 million years earlier than they thought, according to a study published in PNAS.
The sponge existed during the Paleozoic, a time span between 541 and 252 million years ago. The name of the era translates to 'ancient life.' The oldest animals on Earth appeared just before the start of this time, and this special sponge or type of animal might have played a real role in creating the modern coral reef system. And a unique trait they possessed appears to explain why.
L. leizunia used fluorapatite to build its skeleton, a feature previously unknown to sponges, as the study states. Fluorapatite, a phosphate mineral, manifests as glassy crystals in igneous rocks. Specifically, it confirmed that this group of organisms was the first animal phylum known to have used all three principal biominerals: silica, calcium carbonate, and calcium phosphate.
According to the study, this 'unique combination' has given scientists unprecedented insights into the stromatoporoid sponges and key reef-builders during the Paleozoic era, which was marked by an abundant, dramatic increase in marine biodiversity.
'The presence of phosphatic skeletons in this early stromatoporoid expands our understanding of biomineralization strategies in early animals and suggests that the genetic toolkit for diverse biomineralization strategies may have been present in sponges," the study states.
As Phys explains, South China is renowned for its exceptional fossil preservation and its diverse Early Paleozoic marine ecosystems. Already, researchers have gleaned valuable information about the Ordovician strata from this treasure trove in China, the second period out of six that comprised the Paleozoic Era. Within this time frame, the planet saw an early diversification of marine life known as the Great Ordovician Biodiversification Event (GOBE).
The Lophiostroma leizunia sponge highlights a flourishing moment in ancient life, demonstrating that skeletal reefs had developed much earlier than scientists previously believed. It provides "insights into the evolutionary dynamics of biomineralization and the rise of metazoan-dominated reef ecosystems during a critical period of Earth's history.'