Tokyo Gakugei University, the University of Tokyo, and the Nakagawa Town Eco Museum Center in Nakagawa Town, Hokkaido, announced that they have found many tooth fossils of the already extinct Orsacodonto family Sphenodas shark in the strata located on the tributary of the Teshio River in the town.In full form, this is the second report in the world and the first from the Pacific Rim.
Nakagawa Town, located in the northern part of Hokkaido, is a world-famous fossil producing area, and various fossils such as ammonites, sharks, and dinosaurs have been excavated so far.The excavation site this time is the late Cretaceous (about 8900 million years ago) strata of the Abeshinai River, a tributary of the Teshio River.
Both the elongated crown and the wide root are almost completely preserved in this excavated specimen, which is a characteristic inverted T that is unparalleled in comparison with modern shark teeth. Character-shaped fossils are also included.This inverted T-shaped shark tooth fossil was revealed to belong to the genus Sphenodas of the Orsacodonto family from its characteristic crown and root.The Orsacodonto family is a member of the primitive shark family and is already extinct.The teeth of the genus Sphenodas are fragile due to their characteristic shape, and among the fossils of Sphenodas found in the Cretaceous strata, only one fully preserved specimen has been reported worldwide.
This specimen enables detailed comparisons that were previously difficult with incomplete fossils and is of great importance for the study of biodiversity and classification of Cretaceous seas.In Nakagawa Town, fossils of Cretaceous creatures, including this Sphenodas, have been discovered one after another, and the research team hopes to continue excavation and investigation from the town's Eco Museum Center as a starting point.
