I must admit Tenontosaurus impressed me (SPOILER)
For a big, slow relatively unintelligent dinosaur with quite a few weak points, it did quite well against its faster-moving opponents. Took out 2 when conditions were most in its favor, and 4 more when it was really fighting against the odds. Six raptors put in their grave just to take it out. Not a pushover.
"Fluoride doesn't prevent tooth decay. It does render teeth detectable by spy satellite." -JL