pine cone

In the Early Pleistocene, about two million years ago, this pine cone cob was driftwood in the paleo Santa Fe River. The waterlogged wood sank to the bottom in a basin in the river channel. They became buried in a highly organic mud during seasonal flooding.

This anaerobic, low-energy burial preserved fine details such as bark and even insect borings. The cob is thoroughly mineralized with apatite -- it 'clanks' when two pieces are tapped together.  It is not "silicified" as labeled. 

This pine cone cob is dated biochronologically by the vertebrate fossils also found in the mud, notably Holmesina floridana, a giant armadillo. Fossils of the beavers Castor and Castoroides, muskrats, grebes, cormorants, ducks, and large fish suggest that this was a backwater pool in the river.