Fossil Ginkgo leaves- Sentinel Butte Formation, Morton County, North Dakota. by sysadmin | May 12, 2016 | BlogFossil Ginkgo leaves- Sentinel Butte Formation, Morton County, North Dakota. Paleocene – 59 Mya. 9″ across large leaf is 9 cm x 8 cm ; small leaf is 4 cm x 3.5 cm
