The oldest dog bones in Japan date from the prehistoric Jomon period and were found in Kanagawa and Aichi prefectures. It is believed that the bones came from the ancestors of the Shiba Inu called Jomon Shiba.
Based on what scientists believe the Jomon Shiba looked like, some breeders have embarked on a project to recreate Jomon Shibas by carefully breeding modern Shibas and producing a dog with a distinctive long snout.
As of 2018 there are only about 300 of these new Jomon Shibas, but you can see for yourself below The life museum at Azabu University in Sagamihara. In addition to the skeleton, the exhibit also includes a taxidermy of a modern Jomon Shiba, so you can see how similar these replicas are to their prehistoric inspiration.