Free Press Journal

Soft sea sponges ruled the world 445 million years ago


Beijing: Sponges may be simple creatures, but they ruled the world some 445 million years ago after the second-largest mass extinction in Earth’s history, according to a new study of a fossil treasure-trove in China.

The end-Ordovician crisis resulted in 85 per cent of species dying out. It was the result of a sudden, intense ice age, followed by an equally rapid warming, and corresponding changes in ocean chemistry and circulation, researchers said.

The plankton started to recover quite quickly, but until now we have known little about life on the deeper parts of the sea floor, they said. Researchers from Chinese Academy of Sciences and National Museum Wales in the UK revealed a new fossil fauna preserving delicate skeletons and soft tissues, from the immediate aftermath of the Ordovician mass extinction.

The Anji Biota was discovered in the bamboo forests of Zhejiang Province, China, in a narrow band of mudstone exposed at several sites up to 10 kilometres apart. The fauna is extraordinarily diverse, with nearly 100 species found in the first phase of collecting.

The surprise, though, is that this diversity is almost entirely composed of sponges. The Anji Biota records an astonishing range of different sponge species, in many different major groups, with a total diversity exceeding that of equivalent modern faunas.