Unusual 550 Million Year Old Fossil Solves Paleontological Paradox

The research offers new insights into the early evolution of animals.
Researchers led by Shuhai Xiao at Virginia Tech have discovered a 550 million-year-old sea sponge fossil, shedding light on a 160 million-year gap in the fossil record. This fossil, which suggests early sponges lacked mineral skeletons, provides new insights into the evolution of one of the earliest animals and influences how paleontologists search for ancient sponges.

At first glance, the simple sea sponge is no creature of mystery. No brain. No gut. No problem dating it back 700 million years. Yet convincing sponge fossils only go back about 540 million years, leaving a 160 million-year gap in the fossil record.

In a paper released June 5 in the journal Nature, Virginia Tech geobiologist Shuhai Xiao and collaborators reported a 550 million-year-old sea sponge from the “lost years” and proposed that the earliest sea sponges had not yet developed mineral skeletons, offering new parameters to the search for the missing fossils.