Juvenile shell of an ammonoid fossil

Width: 20 mm. Juvenile shell of an ammonoid fossil. It is possible that this is a juvenile shell of Parapallasiceras sp. recovered from the same outcrop. Recovered from siltstone of the early-middle Tithonian (Late Jurassic, 150 Ma) Kuzuryu Subgroup in the Tedori Group. The sedimentary environment of the Kuzuryu Subgroup is shallow marine. This outcrop has been thought as a part of the Bathonian-Callovian (Middle Jurassic, 165 Ma) Kaizara Formation, but recovered ammonoid fossils (Parapallasiceras sp.) suggests that it belongs to the Kurotodo Formation.