Tyrannosaurus rex was the undisputed giant of all land predators for 90 years, and in that time it developed the aura of a dinosaurian Muhammad Ali. It was, truly, the greatest. But in 1995 paleontologists in Argentina discovered a new dinosaur, called Giganotosaurus, which was probably heavier and certainly as long as the 40-foot, 70-million-year-old T. rex. And this past year, like the second blow of a one-two punch, came the report of another predator the size of a T. rex, this one from Africa.
For dinosaur paleontologists today, Africa is like the old Wild West, where spectacular fossils like T. rex lay waiting for those who could get to them. In 1993, Paul Sereno of the University of Chicago began organizing expeditions to the Sahara, and despite grueling conditions--You have to really enjoy thinking about where the next oasis will be, he says- -he uncovered interesting specimens in Niger. ...
