Proganochelys

Proganochelys is a genus of extinct, primitive stem-turtle. Proganochelys was named by Georg Baur in 1887 as the oldest turtle in existence at the time. The name Proganochelys comes from the Greek word ganos meaning 'brightness', combined with prefix pro, 'before', and Greek base chelys meaning 'turtle'. Proganochelys is believed to have been around 1 meter in size and herbivorous in nature. Proganochelys had been known as the most primitive stem-turtle for over a century, until the novel discovery of Odontochelys in 2008. Odontochelys and Proganochelys share unique primitive features that are not found in Casichelydia, such as tooth-like structures on the pterygoid and vomer and a plate-like coracoid.

Proganochelys quenstedtii is the only known species of this genus and is among the oldest known stem-turtle species with a complete shell discovered to date, known from fossils found in Germany and Switzerland in strata from the late Triassic, dating to approximately 210 million years ago. The Thailand species "P." ruchae was later described as a separate genus Thaichelys, while the possible Greenland record likely belongs to a separate taxon.