Seeing the invisible history of leaves

If you find a new dinosaur the next time you stick a shovel in the dirt, you'll be famous. But pity the paleobotanists -- they find new leaf fossils every time they dig. Lack of fame is the least of their problems, though. A central obstacle botanists face is the inability to identify all those fossils. Leaves are naturally complex, with an astounding variety of vein and shape patterns. Comprehensive knoweldge and identification are virtually impossible.