Chelus, Dumeril, 1806

Genus CHELUS Dumeril, 1806 View in CoL

Included species. Chelus fimbriata Schneider, 1783 (extant, see Figure 2.1 View FIGURE 2 -6), Chelus colombiana Wood, 1976 ( sensu Cadena et al., 2008) (fossil), Chelus lewisi Wood, 1976 (fossil).

Revised diagnosis. Combined from Gaffney (1977) and Cadena et al. (2008). Chelus differs from all other chelid turtles by: (1) absence of nasal bones; (2) broad exposure of the prefrontals dorsally along the apertura narium; (3) anterior extension of the pterygoid into the apertura narium interna, often separating the vomer from the palatines; (4) extreme flattening of the dorsal skull, particularly in the center; (5) extreme lateral projection of the cavum tympani; (6) medial process of jugal and postorbital lying entirely on dorsal surface of skull; (7) maxilla very reduced in exposure on triturating surface, so that palatine bears lingual ridge; (8) basisphenoid with a bone tissue pattern extremely acicular tapering anteriorly; (9) dorsal surface of the parietals and frontals very rugose, with very deep sulci for scutes; (10) costovertebral tunnel of the carapace; (11) dorsal surface of the carapace ornamented with three prominently raised, longitudinal ridges, one bearing five knobs and extending along the midline of carapace; (12) scar on ventral surface for contact of inguinal buttress restricted to costal 4.