Nature News has a report of a possible new way of reconstructing past climates - measuring the density of veins in fossil leaves.
Benjamin Blonder, an ecologist at the University of Arizona in Tucson working with Brian Enquist, assumed that were many factors affecting vein density, but he set out to make a model that would capture as much of the variation as possible. He collected leaves from about 65 species from temperate North America. His preliminary models suggest that vein density can predict with a surprising degree of accuracy climatic factors temperature and precipitation.