You should be running 2 lots of planning - group and individual - anyway.
So your group planning is dinosaurs...
Susie likes drawing so you get out the chalks / pencils etc and books about dinos so she can choose which ones she wants to draw...
John is really into role play at the moment so you get out the smooth stones, a box to decorate, green paper for leaves etc and help him make a story scene...
Katy is mad about horses and doesn't want to do much else so you adapt it to dinos, make up a story about a dino that looks like a horse and she can gallop it round a map you make of the dino's home...
Does that help?