I was recently reviewing Terrors Beyond Tyr and the Dark Sun Encounters Tables on pages 5-7 and noticed there are at least two monsters that are in the table but I cannot find the source for them.
They are: Earth Serpent and Fire Scorpion.
Page 5 states all monsters in the tables are from the original boxed set, monstrous manual, terrors of the desert and terrors beyond tyr, but I cannot seem to find the two monsters above. I have all these sources except the monster manual for which I just use the internet. But these two monsters evade even the internet it seems.