Tyrannosaurs are called the king of the dinosaurs because of its massive size and terrible teeth; however, scientists have found bigger dinosaurs since the first T. rex was named in 1905.  For a long time scientists believed that the T. rex was an aggressive carnivore, but findings now suggest that he could have been a scavenger due to recent fossil evidence. For instance, the small front arms were discovered 83 years later. This specimen, field name “Stan”, was 65% complete with this excellent skull, an uncommon occurence.  The original fossil now resides in the Black Hills Institute.

Most scientists claim that the T. rex lived over 65 million years ago.  However, there is evidence that there were Tyrannosaurs living fewer than 100,000 years ago.  In March 2005, Science Magazine reported bone tissue in a T. rex fossil with red blood cells still preserved inside.  This evidence alone limits the age of the partially fossilized bone to less than 100,000 years, which is considerablly less than 65 million.