Agadez Region, Niger, September 15, 2009--Scientists excavate the 43-foot-long (13-meter-long) skeleton of a new species of sauropod--or four-legged plant-eater--in an undated photo released this week. (Related: "Bizarre New Dinosaurs Found in Sahara.")

The 170-million-year-old dinosaur, dubbed Spinophorosaurus nigerensis, had a tail studded with bony spikes that the animal likely swung at predators, study authors say in the September 16 edition of the journal PLoS One. Finding such a complete sauropod skeleton is extremely rare, and the new fossil may help scientists piece together the early evolution of the long-necked giants.