`` Triceratops '' were long thought to have possibly used their horns and frills in combat with predators such as `` Tyrannosaurus '' , the idea being discussed first by C. H. Sternberg in 1917 and 70 years later by Robert Bakker .
`` Triceratops '' were long thought to have used their horns and frills in combat with predators such as `` Tyrannosaurus '' . The idea was discussed first in 1917 and again 70 years later by Robert Bakker .