FIGURE 2. Types of planar joints. 1. butt joint. 2. joint with Type-A interdigitations. 3. stepped joint. 4. joint with Type-B interdigitations. 5. scarf joint. 6. joint with Type-C interdigitations. 7. horizonal or transverse slot joint. 8. lap joint (Weishampel 1984). 9. raised scarf joint. 10. recessed scarf joint ('basal shelf' of Kathe 1995). 11. vertical slot joint. 12. asymmetrical horizontal slot joint with a tab and pocket. 13. scarfed tongue in groove. 14. stepped tongue in groove joint. 15. bird's mouth joint. 16. bear's mouth joint. Unbroken line represents external seam whereas dashed line represents portions of internal interface.