Fossil Maple Leaf, Winthrop Formation
Winthrop, WA
Mid-Cretaceous (110 mya)
Robert Niese
In honor of National Fossil Day, here’s a neat fossil from the Winthrop Formation in north-central Washington. This species looks very similar to modern day maple species, but has yet to be formally identified. This particular fossil formation is rife with beautiful plant specimens. By studying the morphology of these fossil leaves, we can estimate the mean annual temperature of the region 110 million years ago. Using this method, scientists estimate that mid-Cretaceous Washington was almost 12 degrees (˚C) warmer than it is today. (Specimen courtesy of the University of Puget Sound, Geology Department)
Northwest Naturalist 