you can find a siamo head at Mt. Lavaflow but it's kinda hard to find it, and it's even harder to find the other parts. I hope this helped.
in rivet ravine
You find it at BB Base.
in the pay-to-dig site
you have to get 50 donation points
in the bb base lol
you can find it at hot spring heights
It is in Rivet Ravine. I believe it is rare because I have the head fossil and it is rare. :)
at hot spring heights
You find it in Rivet Ravine. Hope I helped! :)
up your but & around the corner
fist of all the dinosaur is lambeo and u can find his head in rivet ravine area 2
just dig where you found its head at