You simply can't go wrong with Playmobil. My son is six, is dinosaur mad, and has now collected every bit of the Playmobil dinosaur collection. Yes, it can seem expensive, but the plastic they use is almost bomb-proof! Never had any breakages.
The adult brachiosaurus is quite large, and has moving legs, neck, tail, and jaw. The baby - from memory - only has moving legs and neck. The tree is full of foliage and the usual pre-historic lizards, insects, etc.
The best judge, however, is my son who absolutely loves this and all his other Playmobil dinosaurs.