I found a few in random places myself. I found a wyvern around 59 Lat - 36 Lon (can't remember which). I found a fire dragon around 30 Lat - 25 Lon, 28 Lat - 68, lastly I found a bunch of regular & ancient wyverns around 15 Lat - 83 Lon. There is a very well known trench that's fairly long. There's 2 tunnels mid way through. I found 3 or 4 wyvern eggs in there ranging from level 25 - 100.