During the ritual to become a Reaver, Kolgrim gives The Warden Wyvern blood to drink suggesting dragons are called by different names, there is another species of dragon, or that there is another step in the growth cycle of male/female dragons. The codex description of adult male dragons seems to match the appearance of wyverns from real-life mythology.

Strategies

A strategy for dealing with the dragon found in the ruins through the Brecilian Forest:

• Before going near the center of the hall to trigger the dragon appearing, equip ranged weapons on all characters. This strategy works best if there is a mage in the party.
• After equipping range weapons, try to place your characters in the corners like: Behind the fire torch, between or behind fallen statues, behind the standing Urn next to the entrance, etc.
• This way the dragon will be unable to attack except with its ranged attacks such as Flame Breath and Roar which do minimal damage.
• Send out either Sten or Alistair (preferably Sten because Alistair has more dexterity for range attacks) to lure the dragon.

If everything works correctly, you will have 3 ranged characters behind corners (and Sten if you get him to safety behind a corner) constantly attacking the dragon while its helplessly trying to find a way to attack you. If you have a mage, you can constantly cast spells without much physical resistance from the dragon.

Or:

• Teach Trap-Making to one of the party members
• Create 20-25 pieces of Small Shrapnel Traps (requires 1 Metal Shard and 1 Trap Trigger for each one)
• Stop the party outside the room (hold, and place them on top of the stairs in front of the dragon's chamber)
• Send in the trap-making member, and place all of your shrapnel traps in a narrow line, leading through the entrance; it is possible to lay traps almost on top of each other
• Send in someone to the center to get the dragon's attention, then run back out, luring it into the traps