I've seen all three, they're definitely around. My friend and I had a little look around the redwood on Mizuka recently and didn't see any thylas but we've definitely seen (and been murderised by) them in the smaller redwood on Ogon. They're probably just super rare.

Iguanodon - same thing, they just seem to be super rare. We had been looking around for ages before we just ran into one at random (this was on Mizuka again, at the bottom of the cliffs near the jungle).

We have a base in the desert and we see Archas around occasionally. Again, probably just a rare spawn.

The Thylacoleo are in the Redwood Biomes, quite often on the floor even found them on the big Mushrooms , rebalanced my server using the dino weight multipliers so have resonable numbers of most dinos, plus it runs at 1.5 dino multiplier.

Yeah i've had to increase dino count by 2x and have seen thylacleo and one iguanodon. Certain dinos seem to be super rare like the plesio and mosa also. Thanks.

I have the dino multiplier at 1.5x and used the weight multipliers as follows in the game ini
DinoSpawnWeightMultipliers=(DinoNameTag= Therizinosaurus,SpawnWeightMultiplier=63.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Spino,SpawnWeightMultiplier=80.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Baryonyx,SpawnWeightMultiplier=75.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.2)
DinoSpawnWeightMultipliers=(DinoNameTag= Direbear,SpawnWeightMultiplier=65.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Bigfoot,SpawnWeightMultiplier=60.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.15)
DinoSpawnWeightMultipliers=(DinoNameTag= Iguanodon,SpawnWeightMultiplier=55.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Achatina,SpawnWeightMultiplier=200.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=1.0)
DinoSpawnWeightMultipliers=(DinoNameTag= Archa,SpawnWeightMultiplier=95.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.25)
DinoSpawnWeightMultipliers=(DinoNameTag= Monkey,SpawnWeightMultiplier=80.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Paracer,SpawnWeightMultiplier=110.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=1.0)
DinoSpawnWeightMultipliers=(DinoNameTag= Tapejara,SpawnWeightMultiplier=52.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Thylacoleo,SpawnWeightMultiplier=100.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=1.0)
DinoSpawnWeightMultipliers=(DinoNameTag= Terrorbird,SpawnWeightMultiplier=52.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Troodon,SpawnWeightMultiplier=80.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.2)
DinoSpawnWeightMultipliers=(DinoNameTag= Dimorph,SpawnWeightMultiplier=80.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.25)
DinoSpawnWeightMultipliers=(DinoNameTag= Carno,SpawnWeightMultiplier=2.5,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Diplo,SpawnWeightMultiplier=32.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Diplocaulus,SpawnWeightMultiplier=100.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.25)
DinoSpawnWeightMultipliers=(DinoNameTag= Ant,SpawnWeightMultiplier=180.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=1.0)
DinoSpawnWeightMultipliers=(DinoNameTag= Dragonfly,SpawnWeightMultiplier=200.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=1.0)
DinoSpawnWeightMultipliers=(DinoNameTag= Phiomia,SpawnWeightMultiplier=85.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.18)
DinoSpawnWeightMultipliers=(DinoNameTag= Salmon,SpawnWeightMultiplier=50.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Compy,SpawnWeightMultiplier=36.0,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Manta,SpawnWeightMultiplier=0.03,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.02)
DinoSpawnWeightMultipliers=(DinoNameTag= Leedsichthys,SpawnWeightMultiplier=0.04,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.02)
DinoSpawnWeightMultipliers=(DinoNameTag= Mega,SpawnWeightMultiplier=0.17,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Bronto,SpawnWeightMultiplier=0.3,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Basilosaurus,SpawnWeightMultiplier=0.15,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Eel,SpawnWeightMultiplier=0.5,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Dodo,SpawnWeightMultiplier=3.70,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.4)
DinoSpawnWeightMultipliers=(DinoNameTag= Ichthyornis,SpawnWeightMultiplier=0.25,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Turtle,SpawnWeightMultiplier=0.75,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.1)
DinoSpawnWeightMultipliers=(DinoNameTag= Coel,SpawnWeightMultiplier=0.33,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.08)
DinoSpawnWeightMultipliers=(DinoNameTag= Dolphin,SpawnWeightMultiplier=0.30,OverrideSpawnLimitPercentage=true,SpawnLimitPercentage=0.08)

Some of the dinos just don't alter, but most do. This increases most of the rare dinos to the levels seen on the Island or Centre and yes I like Troodons :), it does reduce the level of mantas and leeds to centre map levels but results in a high level of coel.
There's no calculations for this it's all trial and error alter one and it can effect others.

Thank you some of these are useful

Just need to add Dimetrodons,sarco,kaprosuchus and titanboa

Originally posted by Exiledknight:

Has anyone seen the thylacleo, iguanodon or archeoptyeryx spawn on the map I have looked all over and can't find any?

you havent looked all over the map...lol kid better try harder