8Fossil sites
Hiraiso Formation
Hiraiso Formation in Japan: 8 fossil sites. Typical age: 249–247 million years (Triassic, Cretaceous).
8Fossil sites
3Finds
249–247 million yearsTypical age
TriassicMain period
Where its fossils were found
CretaceousTriassic
By geological period
Cretaceous1
Triassic7
What was found
Mosasaurs · 1Plotosaurus
Ammonites · 2Deweveria, Tirolites
Towns with the most fossil sites nearby
Other formations of the same period
Triassic