Harvestmen (Arachnida: Opiliones) are a common and widespread group, the most familiar of which are recognizable by their small, rounded bodies and long, slender legs ('daddy long-legs'). Their fossil record is generally poor, but new and exceptionally well-preserved harvestmen have been found in the famous 400-million-year-old Rhynie cherts of Scotland. These remarkable and surprisingly modern-looking fossils include male and female genital structures (a penis and ovipositor) and branching tracheal tubes - providing the oldest unequivocal evidence in any arthropod for air-breathing through the tracheae.