Since I'm a huge dino buff, I feel compelled to respond.
I apologize if any simiar ideas have been discussed else where on this thread, I haven't read all of it yet. The Beastiary should have about 6 to 10 dino species. I think they should be:
Tyrannosaurus rex (of course)
Velocirapor
Dilophosaurus
Stegosaurus
Triceratops
Apatosaurus (brontosaurus)
Pteranodon
As for new abilites:
Tyrannosaurus should have Frightful Presence, an enhanced tracking ability and some kind of Augmented critical or Devestating critical added to its bite attack. In addition, and T. rex bite attack made on a large sized or bigger creature should cause bleeding damage each round thereafter until healed.
Velociraptor/Deinonychus should have some kind of ability that reflects their nature as pack hunters. Perhaps a bonus to their attacks for each member of the pack. For example, if a pack of raptors has 6 members, then each pack member recieves a +6 bonus to his attacks. This bonus would decrese during a battle as pack members are eliminated, but it would make them a real threat at the start of a fight.
Stegosaurs, like the Tyrannosaurs, could have an Augmented critical tail spike attack.
Triceratops could have a thick hide, giving it damage reduction vs edged weapon attacks.
Apatosaurus could prehaps have a stomp attack. These kinds of dinosaurs (sauropods) could rear up on their hind legs. Imagine the kind of crushing damage a sauropod could cause by slamming down on its target with its front legs. A ground shaking effect could accompany this, knocking prone all foes within 30 feet.
Dilophosaurus can go the Jurassic Park route with the spitting venom.
Pteranodon could perhaps snatch and then drop opponents.
