since 4 year olds thrive on sameness, they do not necessarily appreciate even nice changes like new house. It is not uncommon at all for little children to have trouble adjusting, and though it is a 'phase', its important to remember that they are genuinely afraid. The trick is to take their fear seriously without letting a crop of undesirable habits develop (such as having him become dependent on sleeping with you). These behaviors can be frustrating, particularly when they interfere with your own sleep, but my experience has been that yelling at children when they are afraid makes the situation worse and harder to fix. If you can handle this with skill and compassion, it should resolve soon--hang in there.
Your child will become more persistent in communicating his fear through behavior if he is not feeling understood. Just sitting down and listening to him describe his fears while you say soothing things like "it must feel very scary to imagine that dinosaurs are coming" will help. You can also ask him to draw the dinosaurs or whatever else is bothering him, then either let him rip up the drawings (yelling "Go away dinosaurs!" as he does so can be fun) or put them in a decorated 'worry box'. Shutting the lid on the worry box can help 'make the worries go away.' You can play out his fears with toys, or pretend to be a dinosaur yourself as he practices telling you to go away. Books like When My Worries Get Too Big or other books about being scared of the dark will help too--check out amazon's great collection of used books.
As far as sleeping goes, practice using self-soothing techniques with him before bedtime. Teach him to take deep belly breaths that go in through the nose and out through the mouth (practice with a pinwheel or bubble wand). Try putting a music box or special stuffed animal helper near the bed that he can grab for comfort. Help him pick a song to sing to himself when he wakes up scared (or even a little soothing prayer if you are religious). Make sure he stays in his own bed. You go to him when he wakes, but avoid laying down with him. When you go in, encourage him to use the techniques you have practiced. Acknowledge his fear, but gently steer his focus back to things to do to calm down and go back to sleep. Do a little with him for a couple of minutes, then leave. Gradually reduce the time you spend in there with him and keep it boring.
Thank you so much for your help. It makes alot of sense to me what you said. I will definately try the approaches that you said and post my progress!!