Previous Next / The Denver Museum of Nature & Science paleobotany collections support ongoing research, exhibits, and outreach focused on the fossil plants of the Rocky Mountain region Plants are the basis of all terrestrial ecosystems and have been so since they first colonized land more than 400 million years ago. The paleobotany collections at the Denver Museum of Nature & Science are composed of fossilized plant remains spanning the history of plant life on land. The collection is focused on the Rocky Mountain and Great Plains regions, arguably the most prolific fossil plant-producing regions in the world. The collection is one of the four largest and best curated collections from this region of Late Cretaceous and Paleogene age. Fossil plant specimens include compression and impression fossils on stone matrix, petrified trunks and stems, palynological slides, and bulk samples and residues. Fossil plants are abundant in Colorado. We hold more than 30,000 specimens from Late Cretaceous, Early Paleocene, and Early Eocene strata from the state collected at over 600 salvage sites and natural outcrops since 1991. This collection includes the 64 Ma Castle Rock Rainforest, which numbers nearly 10,000 specimens and represents the oldest known tropical rainforest, and the West Bijou collection, a suite of about 5,000 specimens that tells the story of forest recovery following the extinction of the dinosaurs.