Volcanic ash that settled over a New Mexico forest roughly 74.6 million years ago, during the Late Campanian, preserved more than just leaf imprints; it captured a vivid snapshot of a mature forest where flowering plants already held sway. This paleobotanical miracle—a deposit known as Dori’s tuff—challenges the long-standing theory that the true expansion of angiosperms only began after the asteroid impact 66 million years ago.
Until recently, the prevailing view among paleobotanists was that flowering plants of this era were small and weedy, producing tiny seeds that relied on the wind or simple gravity for dispersal. According to this narrative, large fleshy fruits requiring animal assistance for dispersal only appeared later, alongside the rise of mammals and birds following the extinction of the dinosaurs. However, research from the Jose Creek formation suggests otherwise: ten million years before the great catastrophe, dense forests of large flowering trees, including relatives of laurels and palms, thrived in a hot, humid climate. Dinosaurs in this region reached impressive sizes, as evidenced by the discovery of remains belonging to a large species of tyrannosaur.
The key to this revelation lies in the size of the diaspores—the seeds and their surrounding structures. In most other Cretaceous sites, these are comparable in size to a poppy seed. Here, however, the average size is closer to that of a large blueberry, with some individual fruits reaching a centimeter in length. Such a hundredfold increase in volume indicates that plants were already investing significant resources into each seed and relying on animal dispersers—early mammals and potentially certain herbivorous dinosaurs—to spread them.
The find is uniquely valuable because the ashfall occurred within a matter of days, instantly ‘freezing’ the forest in its tracks. The lower layers of the deposit even preserved ground-level vegetation, while the layers above contain leaves and fruits that fell from the canopy. Scientists essentially ‘walked’ through 1.2 kilometers of this buried forest, collecting nearly 80 different types of fruits and seeds alongside the remains of massive tree trunks. This allowed for the reconstruction of an entire ecosystem in its original state, rather than just isolated species.
The discovery, described by researchers at UC Berkeley led by Cindy Looy, shifts our understanding of exactly when flowering plants began to develop complex interactions with animals. If large diaspores were already present in the Late Cretaceous, it implies that the evolution of reproductive strategies moved in tandem with the rise of angiosperms themselves, rather than waiting for the ecological reset following the mass extinction. The New Mexico forest demonstrates that even in the shadow of the dinosaurs, nature had already crafted mature, diverse communities where plants and animals were interdependent.
Today, flowering plants make up approximately 90% of all land vegetation and provide the foundation for most of the human food supply. They first emerged in the Early Cretaceous, roughly 135 million years ago, and remain the most dynamic and successful plant group on Earth. Understanding that their modern characteristics began to take shape long before the famous mass extinction helps us appreciate the depth and resilience of the ecological bonds we take for granted today.
