Description: This presentation is to illuminate and celebrate the deep roots and ancestry of diatom lineages that led to the diverse and ubiquitous distribution of diatoms. The biostratigraphic record of diatoms spans at least the last 100 million years, with diatom morphological innovation and evolution preserved in Cretaceous records around the globe. Although preservation of original diatom valves is often a problem due to the temporal instability of opaline silica, diatoms can be recovered well in cemented concretions, in amber, and in sediment sequences that were not buried deeply. The goal of this presentation is to put a ‘face’ on some of the oldest physical records of diatoms and discuss the nature of the diatom paleontological records and progress to extend the diatom record further back in time.