This is a rare marine reptile ribs from nodular layer of Hokkaido Island.
it was found in 2019 by Gianpaolo Di Silvestro, in a small stream closer mikasa city.
it was prepared carefully and the small pebble could be a gastrolite. We are not sure but why not.
 
indet. marine reptile.
Late Cretaceous
Upper Yezo Group
Ikushubetsu River
Mikasa
Hokkaido
Japan