Say a prayer for the Tuatara, a type of reptile (Rhyncocephalid) that has survived the mass extinction of the dinosaurs and whose closest relatives became extinct about 60-100 million years ago. It is sometimes called a 'living fossil' and is confined to islands of the New Zealand archipelago.
The gender of embryos is determined by temperature, in a narrow band of time during development. Temperature changes, at a rate unprecedented for 50 million years or more, mean that the species may stop producing females altogether. Climate change, likely to be a result of unsustainable human activity, is the culprit.
Hopefully, enlightened human intervention, e.g. to shade nests at the appropriate time, will be effective in averting extinction.
http://www.abc.net.au/science/articles/2008/07/02/2289889.htm?site=science&topic=enviro
http://www.doc.govt.nz/templates/podcover.aspx?id=33162
http://www.bbc.co.uk/nature/wildfacts/factfiles/3052.shtml
[Why not take a look at www.alternativevet.org , while you're here?]