Can be found in Carno island cave, south west lava cave, south east cave near Stonehenge, Central cave near volcano, and possibly others. They are very rare spawns but if checked regularly you can encounter them if looking to tame.
On Aberration they don’t sleep during daytime so they always have the nighttime buff. On the plus side it means if you tame them they are always at their strongest. By far the best attack mount on the new map.
During the night don't go outside.......you will see glowing eyes and think it's a troodon which is scary enough so you get on your take and then you find out it's not a troodon.....stay inside at night this thing was spawned by fear and death itself and just pray you do not encounter this thing it will kill you...
In the center map they spawn around the pond that's on the floating island. Pick up with a quetz and bring them to a taming pen. I'd only use oviraptor kibble and starve tame it a couple times. Knock it out during the day..let it wake up at night and knock it out again then feed it
Always I've Found them in the cave nearest to the beaver dams opposite the ark island. Beware keep little kibble on them as they wake up regardless at sunset but keep the tame level once you put them back down. Good luck.!