Fossil Day

What Is Fossil Day?

October 15th is "Fossil Day" in Japan, established in 2018 by the Palaeontological Society of Japan. The date commemorates October 15, 1904, when Hisakatsu Yabe, later professor emeritus at Tohoku University, described the unusually coiled ammonite "Nipponites mirabilis" as a new species. The day aims to spark interest in fossils and paleontology.

An Ammonite Named "Stone of Japan"

Nipponites means "stone of Japan." It is a type of ammonite that lived in shallow seas around the Japanese archipelago during the Cretaceous period.

• Established by:Palaeontological Society of Japan (2018)
• Date origin:October 15, 1904, when Hisakatsu Yabe described Nipponites mirabilis as a new species
• Connection:Nipponites is also the symbol of the Palaeontological Society of Japan
• Background:in 2017 the International Palaeontological Association designated the weekend of the second week of October as "International Fossil Day"

The Twisted Shell Once Thought to Be a Deformity

Nipponites has a distinctive shell that twists and bends in complex ways. When first found, only one specimen existed, and many researchers suspected it was simply deformed. In 1926 another specimen with the same coiling was discovered, and it was finally accepted as a species. Later computer analysis reconfirmed that the coiling follows regular rules, and today it is seen as an example of ammonites evolving to adapt to their environment.

Tips for Marking This Day

• Visit a museum to see fossils and ammonites
• Search for photos of Nipponites and marvel at its strange shape
• Learn about dinosaur and other fossils discovered in Japan
• Look for fossils in the stone used in stations and buildings

What Creatures from Millions of Years Ago Can Teach Us

A single fossil can reveal what the Earth looked like long ago and how life evolved. On October 15th, let an ammonite named after Japan take you back to the ancient world.