Diverse Ordovician marine ecosystems were abruptly terminated by the Late Ordovician mass extinction (LOME), when around 85％ of species were eliminated.Previous studies thought early Silurian (～443-433 Ma) recovery of biotic diversity and ecosystem complexity [1] occurred relatively rapidly, in the first few million years of the Silurian [2].However, several new lines of evidence show that the biotic recovery from the LOME may have been more complex than previously thought.Recent studies suggest that the recovery was significantly delayed, with biodiversity taking at least 5 million years to reach the pre-extinction levels [3].