Fig. 3

Comparison of the thoracic regions of Largocephalosaurus qianensis (GMPKU-P-1532-B; a and b), Paraplacodus broilii (PIMUZ T 4287, c), and Eusaurosphargis dalsassoi (PIMUZ A/III 4380, d). a Right half of the rib cage in dorsal view. The rectangle indicates the position of the close-up shown in b. b Close-up of the anterior ribs and osteoderms. Note rugose and slightly depressed surfaces on the ribs’ uncinate processes (indicated by thin stippled lines), that resemble the position where the osteoderms were positioned in situ. c Close-up of the anterior right thoracic ribs shown wide flaring uncinate processes with a smooth bone surface. d Rib with uncinate process and pylon-shaped osteoderm. LO, lateral row osteoderm; RO, rib osteoderm; UP, uncinate process