5.9 Cholydra serpentina (Ridley's sea turtle)
_1.JPG "Ridley's skull lateral")
As the name suggests, this is a fully marine turtle. Turtles (the Chelonia) are amniotes, but their precise relationships are still controversial. Some workers have suggested that they evolved from the parareptiles, while others have argued that turtles are highly modified archosaurs (the latter being the group that contains crocodiles, dinosaurs and birds).
Note the main openings in the skull, emargination of the skull's back margin, and the ear region.
_2.JPG "Ridley's skull dorsal")
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