Comparison of tail skeletons between Archaeopteryx, Sapeornis, Confuciusornis, and chicken ( Gallus gallus). The Archaeopteryx tail was modeled after Gatesy and Dial (1996), as well as the Bavarian, Solnhofen, #11, and Thermopolis specimens. For Sapeornis, the tail was reconstructed from specimens IVPP V13276, STM 15-15, and DNHM-D3078. The Confuciusornis tail was modeled after Chiappe (2007) and specimens GMV-2131, GMV-2132, and GMV-2133. Pygostyles are indicated by arrows. Scale bars equal 2 cm.