Daily Paleo Art Month #19: Odontochelys
Living around 220 million years ago in the Late Triassic of China, Odontochelys was the oldest known of all chelonians. About 40cm long (~16in), it lacked the beak and full armored carapace of its modern relatives, instead possessing a mouth full of teeth and only the plastron on its underside – this was quite literally a “turtle in a half shell”!
The evolutionary history of turtles is rather murky, with little early fossil evidence to work with. They were traditionally classified as the last surviving group of anapsids based on the lack of temporal openings in their skulls, but more recent morphological and molecular studies have placed them firmly within the diapsids. Their exact relationships are still debated, with some scientists considering them to be related to the lepidosaurs (modern lizards, snakes, and tuataras), and others suggesting them to be very closely related to the archosaurs.