The Mary river turtle waddled its way on the list for a number of reasons: it's the only member of its genius, and according to EGDE's website, it became evolutionarily distinct 40 million years ago. Forty million years of Earth's changes, however, wasn't enough to prepare them for 100 years of human intervention.
Their habitat... has been disrupted from dam construction, and the species was widely bought and sold in the pet trade.
Today it's protected by the Australian government, and conservation groups are working to make sure its habitat is preserved.