Description
A small but well-preserved transported assemblage of plant fossils collected from the middle Eocene Torrey Sandstone at Del Mar, California, provides, for the first time, an accurate picture of local climate and vegetation 49 to 50 Ma. The flora includes taxa from estuarine, riparian, and coastal lowland habitats of a paratropical broadleaf forest. Living taxa similar to Torrey flora species inhabit warm temperate to paratropical forests of southeastern China, Mexico, and the southeastern United States. The taxonomic composition and foliar physiognomy of Torrey flora fossils indicate a warm (20 C mean annual temperature), equable (less than 8 C mean annual temperature range), frostless climate, with annual rainfall of between 120 and 150 cm, concentrated during the months of April through September. These conclusions suggest that although a climatic drying trend was well established in western North America as early as 50 Ma, conditions remained mesic in the coastal San Diego region. The occurrence of tropical taxa including Tabernaemontana and Eugenia americana in the Torrey flora indicate that the mean annual temperature of the San Diego area had increased between early and middle Eocene time.
