How do you unlock Dusty Dunes Special?

the easiest way to get all the first 100 vivisaurs, I have found is to send the ones you are missing from the first game. The vivisaurs with special next to a location in the fossilry seem to be extremely rare.

To unlock the "special" part of an area all you have to do is fully upgrade your sonar. And I do mean fully.

ive been looking for specials for a while too. ive been able to find a few, but not all. i think you need to fully upgrade your sonar, and then vivosaurs that say "special" will rarely show up. And btw i used masks to try to find special stuff but i dont think it works