Middle Miocene (Seldovian)
Sucker Creek Formation – Sucker Creek Flora
Malheur County, Oregon, USA
109mm slab with 50mm leaf and 15mm acorn.

Plant. Seed. Association.

Quercus is the genus that includes oaks.  The earliest confidently-known fossils are pollen from the Late Paleocene of Austria, and by the Middle Eocene, oaks are known from North America, Europe, and Asia.  While Quercus originated in tropical forests, it continued to thrive while other trees disappeared or retreated to lower latitudes as climates trended drier and cooler across the Oligocene and Miocene. 

This leaf and acorn was buried during a time when Oregon was warmer than it is now.

At a glance this specimen looks like a bold exclamation point.