Description
Fossil Metasequoia Leaf. In 2005 the Oregon state legislature adopted these leaves of the “Dawn Redwood” as the Oregon state fossil.
These leaves were first described in 1941. Relatives still live today.
The Fossil Metasequoia Leaf is from a tree also called the dawn redwood. Relatives are still alive today so they are considered “Living Fossils” It is a fast-growing conifer tree. But until other redwoods like the sequoia it is deciduous and will shed its leaves in autumn. The dawn redwood has bark and foliage that resemble that of the California redwood but unlike the redwood it will thrive in standing water. And the lower trunks of older trees form wide buttresses similar to the bald cypress.
Fossilized leaves of the dawn redwood can be found in Eocene and Miocene aged rocks throughout Oregon as well as neighboring states such as Washington, Idaho and Montana. Its fossils are particularly abundant in Oregon near the Painted Hills and the towns of Mitchell and Fossil. This one is from the Oligocene Muddy Creek Formation of Beaverhead County, Montana
During the Paleocene and Eocene vast forests of Metasequoia extended quite far north, equivalent to where Northern Canada lies today. At the time temperatures on Earth were significantly warmer, meaning despite the far northern location. So the dawn redwood forests would have been growing in a warm, “tropical” environment. It is likely their deciduous habit evolved to take advantage of the combination of these extreme light patterns of near twenty four hour light during the summer and complete darkness during the winter.
