Yangtze River Fossil Bridges 160-Million-Year Gap in Early Animal History
A 550-million-year-old sponge fossil found along the Yangtze River is filling part of a long-standing 160-million-year discrepancy between molecular-clock estimates and the sponge fossil record. The specimen, about 15 inches long, bears a grid-like surface pattern linked to glass sponges and suggests early sponges may have been soft-bodied with later mineralized parts. This finding, described in Nature, prompts scientists to broaden how and where they search for the earliest traces of animal life.
